Research advances of MYB transcription factors in plant stress resistance and breeding

MYB4 in Lilium pumilum affects plant saline-alkaline tolerance

Lilium pumilum DC (L. pumilum DC) plays an important role in the rational utilization of salinized soil. To explore the molecular mechanism of salt-tolerant L. pumilum, the LpMYB4 was cloned. LpMYB4 close relationship with Bambusa emeiensis and Zea mays MYB4 throughout the phylogenetic tree construction. LpMYB4 protein was found to be localized in the nucleus. Prokaryotic and eukaryotic bacterial solution resistance experiments proved that the exogenous introduction of LpMYB4 made the overexpression strains obtain better survival ability under saline-alkaline stress. Compared with wild-type plants, tobacco plants overexpressing LpMYB4 had better growth and lower leaf wilting and lodging, the content of chlorophyll was higher, the content of hydrogen peroxide and superoxide anion was lower, the activity of peroxidase and superoxide dismutase was higher and the relative conductivity was lower under saline-alkaline stress. The analysis of seed germination and seedling resistance of transgenic plants under salt stress showed that LpMYB4 transgenic seeds were more tolerant to salt stress during germination and growth. Yeast two-hybrid and two-luciferase complementation experiments showed that LpMYB4 interacted with yeast two-hybrid and LpGPX6. The analysis of the role of LpMYB4 in improving plant saline-alkali resistance is helpful to the transformation of plant germplasm resources and has great significance for agriculture and sustainable development.

miRNAs: Primary modulators of plant drought tolerance

Drought is a principal environmental factor that affects the growth and development of plants. Accordingly, plants have evolved adaptive mechanisms to cope with adverse environmental conditions. One of the mechanisms is gene regulation mediated by microRNAs (miRNAs). miRNAs are regarded as primary modulators of gene expression at the post-transcriptional level and have been shown to participate in drought stress response, including ABA response, auxin signaling, antioxidant defense, and osmotic regulation through downregulating the corresponding targets. miRNA-based genetic reconstructions have the potential to improve the tolerance of plants to drought. However, there are few precise classification and discussion of miRNAs in specific response behaviors to drought stress and their applications. This review summarized and discussed the specific response behaviors of miRNAs under drought stress and the role of miRNAs as regulators in the response of plants to drought and highlighted that the modification of miRNAs might effectively improve the tolerance of plants to drought.

Whole genome regulatory effect of MoISW2 and consequences for the evolution of the rice plant pathogenic fungus Magnaporthe oryzae

Isw2 proteins, ubiquitous across eukaryotes, exhibit a propensity for DNA binding and exert dynamic influences on local chromosome condensation in an ATP-dependent fashion, thereby modulating the accessibility of neighboring genes to transcriptional machinery. Here, we report the deletion of a putative MoISW2 gene, yielding substantial ramifications on plant pathogenicity. Subsequent gene complementation and chromatin immunoprecipitation sequencing (ChIP-seq) analyses were conducted to delineate binding sites. RNA sequencing (RNA-seq) assays revealed discernible impacts on global gene regulation along chromosomes in both mutant and wild-type strains, with comparative analyses against 55 external RNA-seq data sets corroborating these findings. Notably, MoIsw2-mediated binding and activities delineate genomic loci characterized by pronounced gene expression variability proximal to MoIsw2 binding sites, juxtaposed with comparatively stable expression in surrounding regions. The contingent genes influenced by MoIsw2 activity predominantly encompass niche-determinant genes, including those encoding secreted proteins, secondary metabolites, and stress-responsive elements, alongside avirulence genes. Furthermore, our investigations unveil a spatial correlation between MoIsw2 binding motifs and known transposable elements (TEs), suggesting a potential interplay wherein TE transposition at these loci could modulate the transcriptional landscape of Magnaporthe oryzae in a strain-specific manner. Collectively, these findings position MoIsw2 as a plausible master regulator orchestrating the delicate equilibrium between genes vital for biomass proliferation, akin to housekeeping genes, and niche-specific determinants crucial for ecological adaptability. Stress-induced TE transposition, in conjunction with MoIsw2 activity, emerges as a putative mechanism fostering enhanced mutagenesis and accelerated evolution of niche-determinant genes relative to housekeeping counterparts.IMPORTANCEIsw2 proteins are conserved in plants, fungi, animals, and other eukaryotes. We show that a fungal Isw2 protein in the rice pathogen Magnaporthe oryzae binds to retrotransposon (RT) DNA motifs and affects the epigenetic gene expression landscape of the fungal genome. Mainly ecological niche determinant genes close to the binding motifs are affected. RT elements occur frequently in DNA between genes in most organisms. They move place and multiply in the genome, especially under physiological stress. We further discuss the Isw2 and RT combined activities as a possible sought-after mechanism that can cause biased mutation rates and faster evolution of genes necessary for reacting to abiotic and biotic challenges. The most important biotic challenges for plant pathogens are the ones from the host plants' innate immunity. The overall result of these combined activities will be an adaptation-directed evolution of niche-determinant genes.

Unveiling the power of MYB transcription factors: Master regulators of multi-stress responses and development in cotton

Plants, being immobile, are subject to environmental stresses more than other creatures, necessitating highly effective stress tolerance systems. Transcription factors (TFs) play a crucial role in the adaptation mechanism as they can be activated by diverse signals and ultimately control the expression of stress-responsive genes. One of the most prominent plant TFs family is MYB (myeloblastosis), which is involved in secondary metabolites, developmental mechanisms, biological processes, cellular architecture, metabolic pathways, and stress responses. Extensive research has been conducted on the involvement of MYB TFs in crops, while their role in cotton remains largely unexplored. We also utilized genome-wide data to discover potential 440 MYB genes and investigated their plausible roles in abiotic and biotic stress conditions, as well as in different tissues across diverse transcriptome databases. This review primarily summarized the structure and classification of MYB TFs biotic and abiotic stress tolerance and their role in secondary metabolism in different crops, especially in cotton. However, it intends to identify gaps in current knowledge and emphasize the need for further research to enhance our understanding of MYB roles in plants.

A generalist regulator: MYB transcription factors regulate the biosynthesis of active compounds in medicinal plants

Medicinal plants are rich in a variety of secondary metabolites with therapeutic value. However, the yields of these metabolites are generally very low, making their extraction both time-consuming and labour-intensive. Transcription factor-targeted secondary metabolic engineering can efficiently regulate the biosynthesis and accumulation of secondary metabolites in medicinal plants. v-Myb avian myeloblastosis viral oncogene homolog (MYB) transcription factors are involved in regulating various morphological and developmental processes, responses to stress, and the biosynthesis of secondary metabolites in plants. This review discusses the biological functions and transcription regulation mechanisms of MYB transcription factors and summarizes research progress concerning MYB transcription factors involved in the biosynthesis of representative active components. In the transcriptional regulatory network, MYB transcription factors regulate multiple synthase genes to mediate the biosynthesis of active compounds. This work will serve as a reference for an in-depth analysis of the MYB transcription factor family in medicinal plants.

Decoding the functionality of plant transcription factors

Transcription factors (TFs) intricately govern cellular processes and responses to external stimuli by modulating gene expression. TFs help plants to balance the trade-off between stress tolerance and growth, thus ensuring their long-term survival in challenging environments. Understanding the factors and mechanisms that define the functionality of plant TFs is of paramount importance for unravelling the intricate regulatory networks governing development, growth, and responses to environmental stimuli in plants. This review provides a comprehensive understanding of these factors and mechanisms defining the activity of TFs. Understanding the dynamic nature of TFs has practical implications for modern molecular breeding programmes, as it provides insights into how to manipulate gene expression to optimize desired traits in crops. Moreover, recent studies also report the functional duality of TFs, highlighting their ability to switch between activation and repression modes; this represents an important mechanism for attuning gene expression. Here we discuss what the possible reasons for the dual nature of TFs are and how this duality instructs the cell fate decision during development, and fine-tunes stress responses in plants, enabling them to adapt to various environmental challenges.

Integrated transcriptome and targeted metabolome analyses provide insights into flavonoid biosynthesis in kiwifruit (Actinidia chinensis)

So far, a variety of metabolite components of kiwifruit have been elucidated. However, the identification and analysis of flavonoids in different tissues of kiwifruit are rarely carried out. In this study, we performed transcriptome and metabolome analyses of roots (Gkf_R), stems (Gkf_T), leaves (Gkf_L), and fruits (Gkf_F) to provide insights into the differential accumulation and regulation mechanisms of flavonoids in kiwifruit. Results showed that a total of 301 flavonoids were identified, in four tissues with different accumulation trends, and a large proportion of flavonoids had high accumulation in Gkf_L and Gkf_R. A total of 84 genes have been identified involved in the flavonoid biosynthesis pathway, and the expression levels of five LAR, two DFR, and one HCT were significantly correlated with the accumulation of 16 flavonoids and co-localized in the flavonoid biosynthesis pathway. In addition, a total of 2362 transcription factor genes were identified, mainly MYBs, bHLHs, ERFs, bZIPs and WRKYs, among which the expression level of bHLH74, RAP2.3L/4L/10L, MYB1R1, and WRKY33 were significantly correlated with 25, 56, 43, and 24 kinds of flavonoids. Our research will enrich the metabolomic data and provide useful information for the directed genetic improvement and application in the pharmaceutical industry of kiwifruit.

The characteristic analysis of TaTDF1 reveals its function related to male sterility in wheat (Triticum aestivum L.)

BACKGROUND

The male sterile lines are an important foundation for heterosis utilization in wheat (Triticum aestivum L.). Thereinto, pollen development is one of the indispensable processes of wheat reproductive development, and its fertility plays an important role in wheat heterosis utilization, and are usually influencing by genes. However, these key genes and their regulatory networks during pollen abortion are poorly understood in wheat.

RESULTS

DEFECTIVE IN TAPETAL DEVELOPMENT AND FUNCTION 1 (TDF1) is a member of the R2R3-MYB family and has been shown to be essential for early tapetal layer development and pollen grain fertility in rice (Oryza sativa L.) and Arabidopsis thaliana. In order to clarify the function of TDF1 in wheat anthers development, we used OsTDF1 gene as a reference sequence and homologous cloned wheat TaTDF1 gene. TaTDF1 is localized in the nucleus. The average bolting time of Arabidopsis thaliana overexpressed strain (TaTDF1-OE) was 33 d, and its anther could be colored normally by Alexander staining solution, showing red. The dominant Mosaic suppression silence-line (TaTDF1-EAR) was blue-green in color, and the anthers were shrimpy and thin. The TaTDF1 interacting protein (TaMAP65) was confirmed using Yeast Two-Hybrid Assay (Y2H) and Bimolecular-Fluorescence Complementation (BiFC) experiments. The results showed that downregulated expression of TaTDF1 and TaMAP65 could cause anthers to be smaller and shrunken, leading to pollen abortion in TaTDF1 wheat plants induced by virus-induced gene-silencing technology. The expression pattern of TaTDF1 was influenced by TaMAP65.

CONCLUSIONS

Thus, systematically revealing the regulatory mechanism of wheat TaTDF1 during anther and pollen grain development may provide new information on the molecular mechanism of pollen abortion in wheat.

miR396b/GRF6 module contributes to salt tolerance in rice

Salinity, as one of the most challenging environmental factors restraining crop growth and yield, poses a severe threat to global food security. To address the rising food demand, it is urgent to develop crop varieties with enhanced yield and greater salt tolerance by delving into genes associated with salt tolerance and high-yield traits. MiR396b/GRF6 module has previously been demonstrated to increase rice yield by shaping the inflorescence architecture. In this study, we revealed that miR396b/GRF6 module can significantly improve salt tolerance of rice. In comparison with the wild type, the survival rate of MIM396 and OE-GRF6 transgenic lines increased by 48.0% and 74.4%, respectively. Concurrent with the increased salt tolerance, the transgenic plants exhibited reduced H2O2 accumulation and elevated activities of ROS-scavenging enzymes (CAT, SOD and POD). Furthermore, we identified ZNF9, a negative regulator of rice salt tolerance, as directly binding to the promoter of miR396b to modulate the expression of miR396b/GRF6. Combined transcriptome and ChIP-seq analysis showed that MYB3R serves as the downstream target of miR396b/GRF6 in response to salt tolerance, and overexpression of MYB3R significantly enhanced salt tolerance. In conclusion, this study elucidated the potential mechanism underlying the response of the miR396b/GRF6 network to salt stress in rice. These findings offer a valuable genetic resource for the molecular breeding of high-yield rice varieties endowed with stronger salt tolerance.

Dissection of Metabolome and Transcriptome-Insights into Capsaicin and Flavonoid Accumulation in Two Typical Yunnan Xiaomila Fruits

Pepper is an economically important vegetable worldwide, containing various specialized metabolites crucial for its development and flavor. Capsaicinoids, especially, are genus-specialized metabolites that confer a spicy flavor to Capsicum fruits. In this work, two pepper cultivars, YB (Capsicum frutescens L.) and JC (Capsicum baccatum L.) pepper, showed distinct differences in the accumulation of capsaicin and flavonoid. However, the molecular mechanism underlying them was still unclear. Metabolome analysis showed that the JC pepper induced a more abundant accumulation of metabolites associated with alkaloids, flavonoids, and capsaicinoids in the red ripening stages, leading to a spicier flavor in the JC pepper. Transcriptome analysis confirmed that the increased expression of transcripts associated with phenylpropanoid and flavonoid metabolic pathways occurred in the JC pepper. Integrative analysis of metabolome and transcriptome suggested that four structural genes, 4CL7, 4CL6, CHS, and COMT, were responsible for the higher accumulation of metabolites relevant to capsaicin and flavonoids. Through weighted gene co-expression network analyses, modules related to flavonoid biosynthesis and potential regulators for candidate genes were identified. The promoter analysis of four candidate genes showed they contained several cis-elements that were bonded to MYB, bZIP, and WRKY transcription factors. Further RT-qPCR examination verified three transcription factors, MYB, bZIP53, and WRKY25, that exhibited increased expression in the red ripening stage of the JC pepper compared to YB, which potentially regulated their expression. Altogether, our findings provide comprehensive understanding and valuable information for pepper breeding programs in the future.

Metabolome and transcriptome integration explored the mechanism of browning in Glycyrrhiza uralensis Fisch cells

Introduction

Glycyrrhiza uralensis Fisch, a traditional Chinese medicinal herb known for its diverse pharmacological effects including heat-clearing, detoxification, phlegm dissolving, and cough relief, has experienced an exponential increase in demand due to its expanding clinical use and development prospects. Currently, large-scale cell culture stands out as one of the most promising biotechnological approaches for producing bioactive compounds from medicinal plants. However, the problem of cell browning represents a significant bottleneck in industrial applications of cell culture.

Methods

This study focuses on the Glycyrrhiza uralensis Fisch cells from the Ordos plateau, aiming to elucidate the enzymatic browning process during plant cell culture. Key substrates and genes involved in enzymatic browning were identified by metabolome and transcriptome analysis of normal and browning cells.

Results

Metabolome analysis reveals significant changes in the levels of chalcone, isoflavone, imidazole-pyrimidine, purine nucleosides, organic oxides, carboxylic acids and their derivatives, benzene and its derivatives, flavonoids, 2-arylated benzofuran flavonoids, diazanaphthalenes and fatty acyls within browning cells. In particular, chalcones, isoflavones, and flavones compounds account for a higher proportion of these changes. Furthermore, these compounds collectively show enrichment in four metabolic pathways: Isoflavone biosynthesis pathway; Cutin suberine and wax biosynthesis pathway; Aminoacyl-tRNA biosynthesis pathway; Isoquinoline alkaloid biosynthesis pathway; Transcriptome analysis revealed that the MYB transcription factor is a key regulator of flavonoid synthesis during the browning process in cells. In addition, 223 differentially expressed genes were identified, including phenylpropane, shikimic acid, glycolysis, and pentose phosphate pathways. Among these genes, 23 are directly involved in flavonoid biosynthesis; qPCR validation showed that eight genes (GlPK, GlPAL, Gl24CL, Gl1PDT, Gl3CHI, GlC4H, Gl2F3'H, and Gl2CCR) were up-regulated in browning cells compared to normal cells. These findings corroborate the sequencing results and underscore the critical role of these genes in cellular browning.

Discussion

Consequently, modulation of their expression offers promising strategies for effective control of cellular browning issues.

Methyl jasmonate-induced bHLH42 mediates tissue-specific accumulation of anthocyanins via regulating flavonoid metabolism-related pathways in Caitai

Anthocyanin is a type of plant secondary metabolite beneficial to human health. The anthocyanin content of vegetable and fruit crops signifies their nutritional quality. However, the molecular mechanism of anthocyanin accumulation, especially tissue-specific accumulation, in Caitai, as well as in other Brassica rapa varieties, remains elusive. In the present study, taking advantage of three kinds of Caitai cultivars with diverse colour traits between leaves and stems, we conducted a comparative transcriptome analysis and identified the molecular pathway of anthocyanin biosynthesis in Caitai leaves and stems, respectively. Our further investigations demonstrate that bHLH42, which is robustly induced by MeJA, closely correlates with tissue-specific accumulation of anthocyanins in Caitai; bHLH42 upregulates the expression of flavonoid/anthocyanin biosynthetic pathway genes to activate anthocyanin biosynthesis pathway, importantly, overexpression of bHLH42 significantly improves the anthocyanin content of Caitai. Our analysis convincingly suggests that bHLH42 induced by jasmonic acid signalling plays a crucial role in tissue-specific accumulation of anthocyanins in Caitai.

Identification and Functional Characterization of the SaMYB113 Gene in Solanum aculeatissimum

The MYB transcription factors (TFs) have substantial functions in anthocyanin synthesis as well as being widely associated with plant responses to various adversities. In the present investigation, we found an unreported MYB TF from Solanum aculeatissimum (a wild relative of eggplant) and named it SaMYB113 in reference to its homologous gene. Bioinformatics analysis demonstrated that the open reading frame of SaMYB113 was 825 bp in length, encoding 275 amino acids, with a typical R2R3-MYB gene structure, and predicted subcellular localization in the nucleus. Analysis of the tissue-specific expression pattern through qRT-PCR showed that the SaMYB113 was expressed at a high level in young stems as well as leaves of S. aculeatissimum. Transgenic Arabidopsis and tobacco plants overexpressing SaMYB113 pertinent to the control of the 35S promoter exhibited a distinct purple color trait, suggesting a significant change in their anthocyanin content. Furthermore, we obtained three tobacco transgenic lines with significant differences in anthocyanin accumulation and analyzed the differences in anthocyanin content by LC-MS/MS. The findings demonstrated that overexpression of SaMYB113 caused tobacco to have considerably raised levels of several anthocyanin components, with the most significant increases in delphinidin-like anthocyanins and cyanidin-like anthocyanins. The qRT-PCR findings revealed significant differences in the expression levels of structural genes for anthocyanin synthesis among various transgenic lines. In summary, this study demonstrated that the SaMYB113 gene has a substantial impact on anthocyanin synthesis, and overexpression of the SaMYB113 gene leads to significant modifications to the expression levels of a variety of anthocyanin-synthesizing genes, which leads to complex changes in anthocyanin content and affects plant phenotypes. This present research offers the molecular foundation for the research of the mechanism of anthocyanin formation within plants, as well as providing some reference for the improvement of traits in solanum crops.

Regulatory mechanisms used by ZmMYB39 to enhance drought tolerance in maize (Zea mays) seedlings

Drought is a significant abiotic stressor that limits maize (Zea mays L.) growth and development. Thus, enhancing drought tolerance is critical for promoting maize production. Our findings demonstrated that ZmMYB39 is an MYB transcription factor with transcriptional activation activity. Drought stress experiments involving ZmMYB39 overexpression and knockout lines indicated that ZmMYB39 positively regulated drought stress tolerance in maize. DAP-Seq, EMSA, dual-LUC, and RT-qPCR provided initial insights into the molecular regulatory mechanisms by which ZmMYB39 enhances drought tolerance in maize. ZmMYB39 directly promoted the expression of ZmP5CS1, ZmPOX1, ZmSOD2, ZmRD22, ZmNAC49, and ZmDREB2A, which are involved in stress resistance. ZmMYB39 enhanced drought tolerance by interacting with and promoting the expression of ZmFNR1, ZmHSP20, and ZmDOF6. Our study offers a theoretical basis for understanding the molecular regulatory networks involved in maize drought stress response. Furthermore, ZmMYB39 serves as a valuable genetic resource for breeding drought-resistant maize.

The transcription factor RhMYB17 regulates the homeotic transformation of floral organs in rose (Rosa hybrida) under cold stress

Low temperatures affect flower development in rose (Rosa hybrida), increasing petaloid stamen number and reducing normal stamen number. We identified the low-temperature-responsive R2R3-MYB transcription factor RhMYB17, which is homologous to Arabidopsis MYB17 by similarity of protein sequences. RhMYB17 was up-regulated at low temperatures, and RhMYB17 transcripts accumulated in floral buds. Transient silencing of RhMYB17 by virus-induced gene silencing decreased petaloid stamen number and increased normal stamen number. According to the ABCDE model of floral organ identity, class A genes APETALA 1 (AP1) and AP2 contribute to sepal and petal formation. Transcription factor binding analysis identified RhMYB17 binding sites in the promoters of rose APETALA 2 (RhAP2) and APETALA 2-LIKE (RhAP2L). Yeast one-hybrid assays, dual-luciferase reporter assays, and electrophoretic mobility shift assays confirmed that RhMYB17 directly binds to the promoters of RhAP2 and RhAP2L, thereby activating their expression. RNA sequencing further demonstrated that RhMYB17 plays a pivotal role in regulating the expression of class A genes, and indirectly influences the expression of the class C gene. This study reveals a novel mechanism for the homeotic transformation of floral organs in response to low temperatures.

The MYB family and their response to abiotic stress in ginger (Zingiber officinale Roscoe)

BACKGROUND

Zingiber officinale Roscoe, colloquially known as ginger, is a crop of significant medicinal and culinary value that frequently encounters adversity stemming from inhospitable environmental conditions. The MYB transcription factors have garnered recognition for their pivotal role in orchestrating a multitude of plant biological pathways. Nevertheless, the enumeration and characterization of the MYBs within Z. officinale Roscoe remains unknown. This study embarks on a genome-wide scrutiny of the MYB gene lineage in ginger, with the aim of cataloging all ZoMYB genes implicated in the biosynthesis of gingerols and curcuminoids, and elucidating their potential regulatory mechanisms in counteracting abiotic stress, thereby influencing ginger growth and development.

RESULTS

In this study, we identified an MYB gene family comprising 231 members in ginger genome. This ensemble comprises 74 singular-repeat MYBs (1R-MYB), 156 double-repeat MYBs (R2R3-MYB), and a solitary triple-repeat MYB (R1R2R3-MYB). Moreover, a comprehensive analysis encompassing the sequence features, conserved protein motifs, phylogenetic relationships, chromosome location, and gene duplication events of the ZoMYBs was conducted. We classified ZoMYBs into 37 groups, congruent with the number of conserved domains and gene structure analysis. Additionally, the expression profiles of ZoMYBs during development and under various stresses, including ABA, cold, drought, heat, and salt, were investigated in ginger utilizing both RNA-seq data and qRT-PCR analysis.

CONCLUSION

This work provides a comprehensive understanding of the MYB family in ginger and lays the foundation for the future investigation of the potential functions of ZoMYB genes in ginger growth, development and abiotic stress tolerance of ginger.

Identification of cysteine-rich receptor-like kinase gene family in potato: revealed StCRLK9 in response to heat, salt and drought stresses

The investigation into cysteine-rich receptor-like kinases (CRLKs) holds pivotal significance as these conserved, upstream signalling molecules intricately regulate fundamental biological processes such as plant growth, development and stress adaptation. This study undertakes a comprehensive characterisation of CRLKs in Solanum tuberosum (potato), a staple food crop of immense economic importance. Employing comparative genomics and evolutionary analyses, we identified 10 distinct CRLK genes in potato. Further categorisation into three major groups based on sequence similarity was performed. Each CRLK member in potato was systematically named according to its chromosomal position. Multiple sequence alignment and phylogenetic analyses unveiled conserved gene structures and motifs within the same groups. The genomic distribution of CRLKs was observed across Chromosomes 2-5, 8 and 12. Gene duplication analysis highlighted a noteworthy trend, with most gene pairs exhibiting a Ka/Ks ratio greater than one, indicating positive selection of StCRLKs in potato. Salt and drought stresses significantly impacted peroxidase and catalase activities in potato seedlings. The presence of diverse cis -regulatory elements, including hormone-responsive elements, underscored their involvement in myriad biotic and abiotic stress responses. Interestingly, interactions between the phytohormone auxin and CRLK proteins unveiled a potential auxin-mediated regulatory mechanism. A holistic approach combining transcriptomics and quantitative PCR validation identified StCRLK9 as a potential candidate involved in plant response to heat, salt and drought stresses. This study lays a robust foundation for future research on the functional roles of the CRLK gene family in potatoes, offering valuable insights into their diverse regulatory mechanisms and potential applications in stress management.

WRKY22 Transcription Factor from Iris laevigata Regulates Flowering Time and Resistance to Salt and Drought

Iris laevigata Fisch. is an excellent ornamental plant in cold regions due to its unique ornamental ability and strong cold resistance. However, the flowering period of the population is only about 20 days, greatly limiting its potential uses in landscaping and the cutting flower industry. In addition, I. laevigata is often challenged with various abiotic stresses including high salinity and drought in its native habitats. Thus, breeding novel cultivars with delayed flowering time and higher resistance to abiotic stress is of high importance. In this study, we utilized sequencing data from the I. laevigata transcriptome to identify WRKYs and characterized IlWRKY22, a key transcription factor that modulates flowering time and abiotic stress responses. IlWRKY22 is induced by salt and drought stress. We cloned IlWRKY22 and found that it is a Group IIe WRKY localized in the nucleus. Overexpressing IlWRKY22 in Arabidopsis thaliana (L.) Heynh. and Nicotiana tabacum L. resulted in a delayed flowering time in the transgenic plants. We created transgenic N. tabacum overexpressing IlWRKY22, which showed significantly improved resistance to both salt and drought compared to the control plants. Thus, our study revealed a unique dual function of IlWRKY22, an excellent candidate gene for breeding novel Iris cultivars of desirable traits.

CsREV-CsTCP4-CsVND7 module shapes xylem patterns differentially between stem and leaf to enhance tea plant tolerance to drought

Cultivating drought-tolerant tea varieties enhances both yield and quality of tea plants in northern China. However, the mechanisms underlying their drought tolerance remain largely unknown. Here we identified a key regulator called CsREV, which differentially regulates xylem patterns between leaves and stems, thereby conferring drought tolerance in tea plants. When drought occurs, upregulation of CsREV activates the CsVND7a-dependent xylem vessel differentiation. However, when drought persists, the vessel differentiation is hindered as CsVND7a is downregulated by CsTCP4a. This, combined with the CsREV-promoted secondary-cell-wall thickness of xylem vessel, leads to the enhanced curling of leaves, a characteristic closely associated with plant drought tolerance. Notably, this inhibitory effect of CsTCP4a on CsVND7a expression is absent in stems, allowing stem xylem vessels to continuously differentiate. Overall, the CsREV-CsTCP4-CsVND7 module is differentially utilized to shape the xylem patterns in leaves and stems, potentially balancing water transportation and utilization to improve tea plant drought tolerance.

Genome-wide identification of Shaker K+ channel family in Nicotiana tabacum and functional analysis of NtSKOR1B in response to salt stress

Soil salinization poses a mounting global ecological and environmental threat. The identification of genes responsible for negative regulation of salt tolerance and their utilization in crop improvement through gene editing technologies emerges as a swift strategy for the effective utilization of saline-alkali lands. One efficient mechanism of plant salt tolerance is maintaining the proper intracellular K+/Na+ ratio. The Shaker K+ channels play a crucial role in potassium absorption, transport, and intracellular potassium homeostasis in plant cells. Here, the study presents the first genome-wide identification of Shaker K+ channels in Nicotiana tabacum L., along with a detailed bioinformatic analysis of the 20 identified members. Transcriptome analysis revealed a significant up-regulation of NtSKOR1B, an outwardly-rectifying member predominantly expressed in the root tissue of tobacco seedlings, in response to salt stress. This finding was then confirmed by GUS staining of ProNtSKOR1B::GUS transgenic lines and RT-qPCR analysis. Subsequently, NtSKOR1B knockout mutants (ntskor1) were then generated and subjected to salt conditions. It was found that ntskor1 mutants exhibit enhanced salt tolerance, characterized by increased biomass, higher K+ content and elevated K+/Na+ ratios in both leaf and root tissues, compared to wild-type plants. These results indicate that NtSKOR1B knockout inhibits K+ efflux in root and leaf tissues of tobacco seedlings under salt stress, thereby maintaining higher K+/Na+ ratios within the cells. Thus, our study identifies NtSKOR1B as a negative regulator of salt tolerance in tobacco seedlings.

Genome-wide characterization of TCP family and their potential roles in abiotic stress resistance of oat (Avena sativa L.)

The TCP gene family members play multiple functions in plant growth and development and were named after the first three family members found in this family, TB1 (TEOSINTE BRANCHED 1), CYCLOIDEA (CYC), and Proliferating Cell Factor 1/2 (PCF1/2). Nitrogen (N) is a crucial element for forage yield; however, over-application of N fertilizer can increase agricultural production costs and environmental stress. Therefore, the discovery of low N tolerance genes is essential for the genetic improvement of superior oat germplasm and ecological protection. Oat (Avena sativa L.), is one of the world's staple grass forages, but no genome-wide analysis of TCP genes and their roles in low-nitrogen stress has been performed. This study identified the oat TCP gene family members using bioinformatics techniques. It analyzed their phylogeny, gene structure analysis, and expression patterns. The results showed that the AsTCP gene family includes 49 members, and most of the AsTCP-encoded proteins are neutral or acidic proteins; the phylogenetic tree classified the AsTCP gene family members into three subfamilies, and each subfamily has different conserved structural domains and functions. In addition, multiple cis-acting elements were detected in the promoter of the AsTCP genes, which were associated with abiotic stress, light response, and hormone response. The 49 AsTCP genes identified from oat were unevenly distributed on 18 oat chromosomes. The results of real-time quantitative polymerase chain reaction (qRT-PCR) showed that the AsTCP genes had different expression levels in various tissues under low nitrogen stress, which indicated that these genes (such as AsTCP01, AsTCP03, AsTCP22, and AsTCP38) played multiple roles in the growth and development of oat. In conclusion, this study analyzed the AsTCP gene family and their potential functions in low nitrogen stress at the genome-wide level, which lays a foundation for further analysis of the functions of AsTCP genes in oat and provides a theoretical basis for the exploration of excellent stress tolerance genes in oat. This study provides an essential basis for future in-depth studies of the TCP gene family in other oat genera and reveals new research ideas to improve gene utilization.

Pepper defense against Ralstonia solanacearum and High-temperature stress is positively regulated by CaMYB59

We have functionally evaluated a transcription factor CaMYB59 for its role in pepper immune responses to Ralstonia solanacearum attack and high temperature-high humidity (HTHH). Exposure to R. solanacearum inoculation (RSI) and HTHH resulted in up-regulation of this nucleus-localized TF. Function of this TF was confirmed by performing loss of function assay of CaMYB59 by VIGS (virus-induced gene silencing). Plants with silenced CaMYB59 displayed not only compromised pepper immunity against RSI but also impaired tolerance to HTHH along with decreased hypersensitive response (HR). This impairment in defense function was fully linked with low induction of stress-linked genes like CaPO2, CaPR1, CaAcc and thermo-tolerance linked CaHSP24 as well as CaHsfB2a. Conversely, transient overexpression of CaMYB59 enhanced pepper immunity. This reveals that CaMYB59 positively regulated host defense against RSI and HTHH by means of HR like mimic cell death, H2O2 production and up-regulation of defense as well as thermo-tolerance associated genes. These changes in attributes collectively confirm the role of CaMYB59 as a positive regulator of pepper immunity against R. solanacearum. We recommend that such positive regulation of pepper defense is dynamically supported by phyto-hormone signaling and transcriptional web of defense genes. These integrated and interlinked events stabilize plant growth and survival under abiotic and biotic stresses.

Integrative physiological, metabolomic, and transcriptomic analysis reveals the drought responses of two apple rootstock cultivars

BACKGROUND

Drought is considered the main environmental factor restricting apple production and thus the development of the apple industry. Rootstocks play an important role in enhancing the drought tolerance of apple plants. Studies of the physiology have demonstrated that 'ZC9-3' is a strong drought-resistant rootstock, whereas 'Jizhen-2' is a weak drought-resistant rootstock. However, the metabolites in these two apple rootstock varieties that respond to drought stress have not yet been characterized, and the molecular mechanisms underlying their responses to drought stress remain unclear.

RESULTS

In this study, the physiological and molecular mechanisms underlying differences in the drought resistance of 'Jizhen-2' (drought-sensitive) and 'ZC9-3' (drought-resistant) apple rootstocks were explored. Under drought stress, the relative water content of the leaves was maintained at higher levels in 'ZC9-3' than in 'Jizhen-2', and the photosynthetic, antioxidant, and osmoregulatory capacities of 'ZC9-3' were stronger than those of 'Jizhen-2'. Metabolome analysis revealed a total of 95 and 156 differentially accumulated metabolites in 'Jizhen-2' and 'ZC9-3' under drought stress, respectively. The up-regulated metabolites in the two cultivars were mainly amino acids and derivatives. Transcriptome analysis revealed that there were more differentially expressed genes and transcription factors in 'ZC9-3' than in 'Jizhen-2' throughout the drought treatment. Metabolomic and transcriptomic analysis revealed that amino acid biosynthesis pathways play key roles in mediating drought resistance in apple rootstocks. A total of 13 metabolites, including L-α-aminoadipate, L-homoserine, L-threonine, L-isoleucine, L-valine, L-leucine, (2S)-2-isopropylmalate, anthranilate, L-tryptophan, L-phenylalanine, L-tyrosine, L-glutamate, and L-proline, play an important role in the difference in drought resistance between 'ZC9-3' and 'Jizhen-2'. In addition, 13 genes encoding O-acetylserine-(thiol)-lyase, S-adenosylmethionine synthetase, ketol-acid isomeroreductase, dihydroxyacid dehydratase, isopropylmalate isomerase, branched-chain aminotransferase, pyruvate kinase, 3-dehydroquinate dehydratase/shikimate 5-dehydrogenase, N-acetylglutamate-5-P-reductase, and pyrroline-5-carboxylate synthetase positively regulate the response of 'ZC9-3' to drought stress.

CONCLUSIONS

This study enhances our understanding of the response of apple rootstocks to drought stress at the physiological, metabolic, and transcriptional levels and provides key insights that will aid the cultivation of drought-resistant apple rootstock cultivars. Especially, it identifies key metabolites and genes underlying the drought resistance of apple rootstocks.

Integrated transcriptome and metabolome analysis reveals anthocyanin biosynthesis mechanisms in pepper (Capsicum annuum L.) leaves under continuous blue light irradiation

BACKGROUND

Different metabolic compounds give pepper leaves and fruits their diverse colors. Anthocyanin accumulation is the main cause of the purple color of pepper leaves. The light environment is a critical factor affecting anthocyanin biosynthesis. It is essential that we understand how to use light to regulate anthocyanin biosynthesis in plants.

RESULT

Pepper leaves were significantly blue-purple only in continuous blue light or white light (with a blue light component) irradiation treatments, and the anthocyanin content of pepper leaves increased significantly after continuous blue light irradiation. This green-to-purple phenotype change in pepper leaves was due to the expression of different genes. We found that the anthocyanin synthesis precursor-related genes PAL and 4CL, as well as the structural genes F3H, DFR, ANS, BZ1, and F3'5'H in the anthocyanin synthesis pathway, had high expression under continuous blue light irradiation. Similarly, the expression of transcription factors MYB1R1-like, MYB48, MYB4-like isoform X1, bHLH143-like, and bHLH92-like isoform X3, and circadian rhythm-related genes LHY and COP1, were significantly increased after continuous blue light irradiation. A correlation network analysis revealed that these transcription factors and circadian rhythm-related genes were positively correlated with structural genes in the anthocyanin synthesis pathway. Metabolomic analysis showed that delphinidin-3-O-glucoside and delphinidin-3-O-rutinoside were significantly higher under continuous blue light irradiation relative to other light treatments. We selected 12 genes involved in anthocyanin synthesis in pepper leaves for qRT-PCR analysis, and the accuracy of the RNA-seq results was confirmed.

CONCLUSIONS

In this study, we found that blue light and 24-hour irradiation together induced the expression of key genes and the accumulation of metabolites in the anthocyanin synthesis pathway, thus promoting anthocyanin biosynthesis in pepper leaves. These results provide a basis for future study of the mechanisms of light quality and photoperiod in anthocyanin synthesis and metabolism, and our study may serve as a valuable reference for screening light ratios that regulate anthocyanin biosynthesis in plants.

Specific ABA-independent tomato transcriptome reprogramming under abiotic stress combination

Crops often have to face several abiotic stresses simultaneously, and under these conditions, the plant's response significantly differs from that observed under a single stress. However, up to the present, most of the molecular markers identified for increasing plant stress tolerance have been characterized under single abiotic stresses, which explains the unexpected results found when plants are tested under real field conditions. One important regulator of the plant's responses to abiotic stresses is abscisic acid (ABA). The ABA signaling system engages many stress-responsive genes, but many others do not respond to ABA treatments. Thus, the ABA-independent pathway, which is still largely unknown, involves multiple signaling pathways and important molecular components necessary for the plant's adaptation to climate change. In the present study, ABA-deficient tomato mutants (flacca, flc) were subjected to salinity, heat, or their combination. An in-depth RNA-seq analysis revealed that the combination of salinity and heat led to a strong reprogramming of the tomato transcriptome. Thus, of the 685 genes that were specifically regulated under this combination in our flc mutants, 463 genes were regulated by ABA-independent systems. Among these genes, we identified six transcription factors (TFs) that were significantly regulated, belonging to the R2R3-MYB family. A protein-protein interaction network showed that the TFs SlMYB50 and SlMYB86 were directly involved in the upregulation of the flavonol biosynthetic pathway-related genes. One of the most novel findings of the study is the identification of the involvement of some important ABA-independent TFs in the specific plant response to abiotic stress combination. Considering that ABA levels dramatically change in response to environmental factors, the study of ABA-independent genes that are specifically regulated under stress combination may provide a remarkable tool for increasing plant resilience to climate change.

OsMYB58 Negatively Regulates Plant Growth and Development by Regulating Phosphate Homeostasis

Phosphate (Pi) starvation is a critical factor limiting crop growth, development, and productivity. Rice (Oryza sativa) R2R3-MYB transcription factors function in the transcriptional regulation of plant responses to various abiotic stresses and micronutrient deprivation, but little is known about their roles in Pi starvation signaling and Pi homeostasis. Here, we identified the R2R3-MYB transcription factor gene OsMYB58, which shares high sequence similarity with AtMYB58. OsMYB58 expression was induced more strongly by Pi starvation than by other micronutrient deficiencies. Overexpressing OsMYB58 in Arabidopsis thaliana and rice inhibited plant growth and development under Pi-deficient conditions. In addition, the overexpression of OsMYB58 in plants exposed to Pi deficiency strongly affected root development, including seminal root, lateral root, and root hair formation. Overexpressing OsMYB58 strongly decreased the expression of the rice microRNAs OsmiR399a and OsmiR399j. By contrast, overexpressing OsMYB58 strongly increased the expression of rice PHOSPHATE 2 (OsPHO2), whose expression is repressed by miR399 during Pi starvation signaling. OsMYB58 functions as a transcriptional repressor of the expression of its target genes, as determined by a transcriptional activity assay. These results demonstrate that OsMYB58 negatively regulates OsmiR399-dependent Pi starvation signaling by enhancing OsmiR399s expression.

Genome-wide identification of the Pyrus R2R3-MYB gene family and PhMYB62 regulation analysis in Pyrus hopeiensis flowers at low temperature

The R2R3-MYB gene family play an important role in plant growth, development and stress responses. In this study, a total of 122 PcoR2R3-MYB genes were identified and grouped into 26 clades in pear. And these PcoMYBs were unevenly distributed among 17 chromosomes. The sequence characteristics, conversed motifs, exon/intron structures, classification, duplication events and cis-acting elements were also investigated. The gene duplication events showed that segmental duplication may play key roles in expansion of the PcoMYB gene family. Pyrus hopeiensis, which is a valuable wild resource, has strong cold resistance. An integrative analyses of miRNA and mRNA showed that PhMYB62 was involved in regulating low-temperature stress in P. hopeiensis flower organs. Subcellular localization analysis showed that PhMYB62 protein was specifically localized to the nucleus. The result of DAP-seq showed that PhMYB62 responded to low-temperature stress in P. hopeiensis by regulating TFs, which were associated with plant stress resistance, and POD, GAUT12, AUX28 and CHS genes. Subsequently, yeast one-hybrid verified that PhMYB62 could bind and activate the promoter of POD gene. The current study would provide a comprehensive information for further functional research on the stress-responsive R2R3-MYB gene candidates in pear, and may help to identify the genes associated with cold resistance for the cultivation of cold-resistant pear varieties.

Genome-wide association studies for earliness, MYMIV resistance, and other associated traits in mungbean (Vigna radiata L. Wilczek) using genotyping by sequencing approach

Yellow mosaic disease (YMD) remains a major constraint in mungbean (Vigna radiata (L.)) production; while short-duration genotypes offer multiple crop cycles per year and help in escaping terminal heat stress, especially during summer cultivation. A comprehensive genotyping by sequencing (GBS)-based genome-wide association studies (GWAS) analysis was conducted using 132 diverse mungbean genotypes for traits like flowering time, YMD resistance, soil plant analysis development (SPAD) value, trichome density, and leaf area. The frequency distribution revealed a wide range of values for all the traits. GBS studies identified 31,953 high-quality single nucleotide polymorphism (SNPs) across all 11 mungbean chromosomes and were used for GWAS. Structure analysis revealed the presence of two genetically distinct populations based on ΔK. The linkage disequilibrium (LD) varied throughout the chromosomes and at r2 = 0.2, the mean LD decay was estimated as 39.59 kb. Two statistical models, mixed linear model (MLM) and Bayesian-information and Linkage-disequilibrium Iteratively Nested Keyway (BLINK) identified 44 shared SNPs linked with various candidate genes. Notable candidate genes identified include FPA for flowering time (VRADI10G01470; chr. 10), TIR-NBS-LRR for mungbean yellow mosaic India virus (MYMIV) resistance (VRADI09G06940; chr. 9), E3 ubiquitin-protein ligase RIE1 for SPAD value (VRADI07G28100; chr. 11), WRKY family transcription factor for leaf area (VRADI03G06560; chr. 3), and LOB domain-containing protein 21 for trichomes (VRADI06G04290; chr. 6). In-silico validation of candidate genes was done through digital gene expression analysis using Arabidopsis orthologous (compared with Vigna radiata genome). The findings provided valuable insight for marker-assisted breeding aiming for the development of YMD-resistant and early-maturing mungbean varieties.

Genome-Wide Analysis of R2R3-MYB Genes and Functional Characterization of SmMYB75 in Eggplant Fruit Implications for Crop Improvement and Nutritional Enhancement

R2R3-MYB represents a substantial gene family that plays diverse roles in plant development. In this study, 102 SmR2R3-MYB genes were identified from eggplant fruit and classified into 31 subfamilies. Analysis indicated that segmental duplication events played a pivotal role in the expansion of the SmR2R3-MYB gene family. Furthermore, the prediction of miRNAs targeting SmR2R3-MYB genes revealed that 60 SmR2R3-MYBs are targeted by 57 miRNAs, with specific miRNAs displaying varying numbers of target genes, providing valuable insights into the regulatory functions of miRNAs in plant growth, development, and responses to stress conditions. Through expression profile analysis under various treatment conditions, including low temperature (4 °C), plant hormone (ABA, Abscisic acid), and drought stress (PEG, Polyethylene glycol), diverse and complex regulatory mechanisms governing SmR2R3-MYB gene expression were elucidated. Notably, EGP21875.1 and EGP21874.1 exhibited upregulation in expression under all treatment conditions. Transcriptome and metabolome analyses demonstrated that, apart from anthocyanins (delphinidin-3-O-glucoside, cyanidin-3-O-(6-O-p-coumaroyl)-glucoside, and malvidin-3-O-(6-O-p-coumaroyl)-glucoside), overexpression of SmMYB75 could also elevate the content of various beneficial compounds, such as flavonoids, phenolic acids, and terpenes, in eggplant pulp. This comprehensive study enhances our understanding of SmR2R3-MYB gene functions and provides a strong basis for further research on their roles in regulating anthocyanin synthesis and improving eggplant fruit quality.

Genome-wide identification, classification and expression analysis of MYB gene family in coconut (Cocos nucifera L.)

MYB transcription factors regulate the growth, development, and secondary metabolism of plant species. To investigate the origin of color variations in coconut pericarp, we identified and analyzed the MYB gene family present in coconut. According to the sequence of MYB genes in Arabidopsis thaliana, homologous MYB gene sequences were found in the whole genome database of coconut, the conserved sequence motifs within MYB proteins were analyzed by Motif Elicitation (MEME) tool, and the sequences without conservative structure were eliminated. Additionally, we employed RNA-seq technology to generate gene expression signatures of the R2R3-MYB genes across distinctive coconut parts exhibiting diverse colors. To validate these profiles, we conducted quantitative PCR (qPCR). Through comprehensive genome-wide screening, we successfully identified a collection of 179 MYB genes in coconut. Subsequent phylogenetic analysis categorized these 179 coconut MYB genes into 4-subfamilies: 124 R2R3-MYB, 4 3R-MYB types, 4 4R-MYB type, and 47 unknown types. Furthermore, these genes were further divided into 34 subgroups, with 28 of these subgroups successfully classified into known subfamilies found in Arabidopsis thaliana. By mapping the CnMYB genes onto the 16 chromosomes of the coconut genome, we unveiled a collinearity association between them. Moreover, a preservation of gene structure and motif distribution was observed across the CnMYB genes. Our research encompassed a thorough investigation of the R2R3-MYB genes present in the coconut genome, including the chromosomal localization, gene assembly, conserved regions, phylogenetic associations, and promoter cis-acting elements of the studied genes. Our findings revealed a collection of 12 R2R3-MYB candidate genes, namely CnMYB8, CnMYB15, CnMYB27, CnMYB28, CnMYB61, CnMYB63, CnMYB68, CnMYB94, CnMYB101, CnMYB150, CnMYB153, and CnMYB164. These genes showed differential expressions in diverse tissues and developmental stages of four coconut species, such as CnMYB68, CnMYB101, and CnMYB28 exhibited high expression in majority of tissues and coconut species, while CnMYB94 and CnMYB164 showed lower expression. These findings shed light on the crucial functional divergence of CnMYB genes across various coconut tissues, suggesting these genes as promising candidate genes for facilitating color development in this important crop.

Genome-Wide Identification and Characterization of MYB Gene Family and Analysis of Its Sex-Biased Expression Pattern in Spinacia oleracea L

The members of the myeloblastosis (MYB) family of transcription factors (TFs) participate in a variety of biological regulatory processes in plants, such as circadian rhythm, metabolism, and flower development. However, the characterization of MYB genes across the genomes of spinach Spinacia oleracea L. has not been reported. Here, we identified 140 MYB genes in spinach and described their characteristics using bioinformatics approaches. Among the MYB genes, 54 were 1R-MYB, 80 were 2R-MYB, 5 were 3R-MYB, and 1 was 4R-MYB. Almost all MYB genes were located in the 0-30 Mb region of autosomes; however, the 20 MYB genes were enriched at both ends of the sex chromosome (chromosome 4). Based on phylogeny, conserved motifs, and the structure of genes, 2R-MYB exhibited higher conservation relative to 1R-MYB genes. Tandem duplication and collinearity of spinach MYB genes drive their evolution, enabling the functional diversification of spinach genes. Subcellular localization prediction indicated that spinach MYB genes were mainly located in the nucleus. Cis-acting element analysis confirmed that MYB genes were involved in various processes of spinach growth and development, such as circadian rhythm, cell differentiation, and reproduction through hormone synthesis. Furthermore, through the transcriptome data analysis of male and female flower organs at five different periods, ten candidate genes showed biased expression in spinach males, suggesting that these genes might be related to the development of spinach anthers. Collectively, this study provides useful information for further investigating the function of MYB TFs and novel insights into the regulation of sex determination in spinach.

Comparative transcriptome analysis revealed that auxin and cell wall biosynthesis play important roles in the formation of hollow hearts in cucumber

BACKGROUND

Hollow heart is a kind of physiological defect that seriously affects the yield, quality, and economic value of cucumber. However, the formation of hollow hearts may relate to multiple factors in cucumber, and it is necessary to conduct analysis.

RESULTS

In this study, hollow and non-hollow fruits of cucumber K07 were used for comparative transcriptome sequencing and analysis. 253 differentially expressed genes and 139 transcription factors were identified as being associated with the formation of hollow hearts. Hormone (auxin) signaling and cell wall biosynthesis were mainly enriched in GO and KEGG pathways. Expression levels of key genes involved in indole-3-acetic acid biosynthesis in carpel were lower in the hollow fruits than non-hollow fruits, while there was no difference in the flesh. The concentration of indole-3-acetic also showed lower in the carpel than flesh. The biosynthetic pathway and content analysis of the main components of the cell wall found that lignin biosynthesis had obvious regularity with hollow heart, followed by hemicellulose and cellulose. Correlation analysis showed that there may be an interaction between auxin and cell wall biosynthesis, and they collectively participate in the formation of hollow hearts in cucumber. Among the differentially expressed transcription factors, MYB members were the most abundant, followed by NAC, ERF, and bHLH.

CONCLUSIONS

The results and analyses showed that the low content of auxin in the carpel affected the activity of enzymes related to cell wall biosynthesis at the early stage of fruit development, resulting in incomplete development of carpel cells, thus forming a hollow heart in cucumber. Some transcription factors may play regulatory roles in this progress. The results may enrich the theory of the formation of hollow hearts and provide a basis for future research.

A novel PGPR strain homologous to Beijerinckia fluminensis induces biochemical and molecular changes involved in Arabidopsis thaliana salt tolerance

The use of PGPR is widely accepted as a promising tool for a more sustainable agricultural production and improved plant abiotic stress resistance. This study tested the ability of PVr_9, a novel bacterial strain, homologous to Beijerinckia fluminensis, to increase salt stress tolerance in A. thaliana. In vitro plantlets inoculated with PVr_9 and treated with 150 mM NaCl showed a reduction in primary root growth inhibition compared to uninoculated ones, and a leaf area significantly less affected by salt. Furthermore, salt-stressed PVr_9-inoculated plants had low ROS and 8-oxo-dG, osmolytes, and ABA content along with a modulation in antioxidant enzymatic activities. A significant decrease in Na+ in the leaves and a corresponding increase in the roots were also observed in salt-stressed inoculated plants. SOS1, NHX1 genes involved in plant salt tolerance, were up-regulated in PVr_9-inoculated plants, while different MYB genes involved in salt stress signal response were down-regulated in both roots and shoots. Thus, PVr_9 was able to increase salt tolerance in A. thaliana, thereby suggesting a role in ion homeostasis by reducing salt stress rather than inhibiting total Na+ uptake. These results showed a possible molecular mechanism of crosstalk between PVr_9 and plant roots to enhance salt tolerance, and highlighted this bacterium as a promising PGPR for field applications on agronomical crops.

Genetic and Epigenetic Responses of Autochthonous Grapevine Cultivars from the 'Epirus' Region of Greece upon Consecutive Drought Stress

Within the framework of preserving and valorizing the rich grapevine germplasm of the Epirus region of Greece, indigenous grapevine (Vitis vinifera L.) cultivars were characterized and assessed for their resilience to abiotic stresses in the context of climate change. The cultivars 'Debina' and 'Dichali' displayed significant differences in their response to drought stress as judged by morpho-physiological analysis, indicating higher drought tolerance for Dichali. Hence, they were selected for further study aiming to identify genetic and epigenetic mechanisms possibly regulating drought adaptability. Specifically, self-rooted and heterografted on 'Richter 110' rootstock plants were subjected to two phases of drought with a recovery period in between. Gene expression analysis was performed for two stress-related miRNAs and their target genes: (a) miRNA159 and putative targets, VvMYB101, VvGATA-26-like, VvTOPLESS-4-like and (b) miRNA156 and putative target gene VvCONSTANS-5. Overall, grafted plants exhibited a higher drought tolerance than self-rooted plants, suggesting beneficial rootstock-scion interactions. Comparative analysis revealed differential gene expression under repetitive drought stresses between the two cultivars as well as between the self-rooted and grafted plants. 'Dichali' exhibited an up-regulation of most of the genes examined, which may be associated with increased tolerance. Nevertheless, the profound down-regulation of VvTOPLESS-4-like (a transcriptional co-repressor of transcription factors) upon drought and the concomitant up-regulation of miRNA159 highlights the importance of this 'miRNA-target' module in drought responsiveness. DNA methylation profiling using MSAP analysis revealed differential methylation patterns between the two genotypes in response to drought. Further investigations of gene expression and DNA methylation will contribute to our understanding of the epigenetic mechanisms underlying grapevine tolerance to drought stress.

Research progress on the roles of actin-depolymerizing factor in plant stress responses

Actin-depolymerizing factors (ADFs) are highly conserved small-molecule actin-binding proteins found throughout eukaryotic cells. In land plants, ADFs form a small gene family that displays functional redundancy despite variations among its individual members. ADF can bind to actin monomers or polymerized microfilaments and regulate dynamic changes in the cytoskeletal framework through specialized biochemical activities, such as severing, depolymerizing, and bundling. The involvement of ADFs in modulating the microfilaments' dynamic changes has significant implications for various physiological processes, including plant growth, development, and stress response. The current body of research has greatly advanced our comprehension of the involvement of ADFs in the regulation of plant responses to both biotic and abiotic stresses, particularly with respect to the molecular regulatory mechanisms that govern ADF activity during the transmission of stress signals. Stress has the capacity to directly modify the transcription levels of ADF genes, as well as indirectly regulate their expression through transcription factors such as MYB, C-repeat binding factors, ABF, and 14-3-3 proteins. Furthermore, apart from their role in regulating actin dynamics, ADFs possess the ability to modulate the stress response by influencing downstream genes associated with pathogen resistance and abiotic stress response. This paper provides a comprehensive overview of the current advancements in plant ADF gene research and suggests that the identification of plant ADF family genes across a broader spectrum, thorough analysis of ADF gene regulation in stress resistance of plants, and manipulation of ADF genes through genome-editing techniques to enhance plant stress resistance are crucial avenues for future investigation in this field.

Characteristics and Functions of MYB (v-Myb avivan myoblastsis virus oncogene homolog)-Related Genes in Arabidopsis thaliana

The MYB (v-Myb avivan myoblastsis virus oncogene homolog) transcription factor family is one of the largest families of plant transcription factors which plays a vital role in many aspects of plant growth and development. MYB-related is a subclass of the MYB family. Fifty-nine Arabidopsis thaliana MYB-related (AtMYB-related) genes have been identified. In order to understand the functions of these genes, in this review, the promoters of AtMYB-related genes were analyzed by means of bioinformatics, and the progress of research into the functions of these genes has been described. The main functions of these AtMYB-related genes are light response and circadian rhythm regulation, root hair and trichome development, telomere DNA binding, and hormone response. From an analysis of cis-acting elements, it was found that the promoters of these genes contained light-responsive elements and plant hormone response elements. Most genes contained elements related to drought, low temperature, and defense and stress responses. These analyses suggest that AtMYB-related genes may be involved in A. thaliana growth and development, and environmental adaptation through plant hormone pathways. However, the functions of many genes do not occur independently but instead interact with each other through different pathways. In the future, the study of the role of the gene in different pathways will be conducive to a comprehensive understanding of the function of the gene. Therefore, gene cloning and protein functional analyses can be subsequently used to understand the regulatory mechanisms of AtMYB-related genes in the interaction of multiple signal pathways. This review provides theoretical guidance for the follow-up study of plant MYB-related genes.

Overexpression of Lolium multiflorum LmMYB1 Enhances Drought Tolerance in Transgenic Arabidopsis

Lolium multiflorum is one of the world-famous forage grasses with rich biomass, fast growth rate and good nutritional quality. However, its growth and forage yield are often affected by drought, which is a major natural disaster all over the world. MYB transcription factors have some specific roles in response to drought stress, such as regulation of stomatal development and density, control of cell wall and root development. However, the biological function of MYB in L. multiflorum remains unclear. Previously, we elucidated the role of LmMYB1 in enhancing osmotic stress resistance in Saccharomyces cerevisiae. Here, this study elucidates the biological function of LmMYB1 in enhancing plant drought tolerance through an ABA-dependent pathway involving the regulation of cell wall development and stomatal density. After drought stress and ABA stress, the expression of LmMYB1 in L. multiflorum was significantly increased. Overexpression of LmMYB1 increased the survival rate of Arabidopsis thaliana under drought stress. Under drought conditions, expression levels of drought-responsive genes such as AtRD22, AtRAB and AtAREB were up-regulated in OE compared with those in WT. Further observation showed that the stomatal density of OE was reduced, which was associated with the up-regulated expression of cell wall-related pathway genes in the RNA-Seq results. In conclusion, this study confirmed the biological function of LmMYB1 in improving drought tolerance by mediating cell wall development through the ABA-dependent pathway and thereby affecting stomatal density.

Sequence Characterization of Extra-Chromosomal Circular DNA Content in Multiple Blackgrass (Alopecurus myosuroides) Populations

Alopecurus myosuroides (blackgrass) is a problematic weed of Western European winter wheat, and its success is largely due to widespread multiple-herbicide resistance. Previous analysis of F2 seed families derived from two distinct blackgrass populations exhibiting equivalent non-target site resistance (NTSR) phenotypes shows resistance is polygenic and evolves from standing genetic variation. Using a CIDER-seq pipeline, we show that herbicide-resistant (HR) and herbicide-sensitive (HS) F3 plants from these F2 seed families as well as the parent populations they were derived from carry extra-chromosomal circular DNA (eccDNA). We identify the similarities and differences in the coding structures within and between resistant and sensitive populations. Although the numbers and size of detected eccDNAs varied between the populations, comparisons between the HR and HS blackgrass populations identified shared and unique coding content, predicted genes, and functional protein domains. These include genes related to herbicide detoxification such as Cytochrome P450s, ATP-binding cassette transporters, and glutathione transferases including AmGSTF1. eccDNA content was mapped to the A. myosuroides reference genome, revealing genomic regions at the distal end of chromosome 5 and the near center of chromosomes 1 and 7 as regions with a high number of mapped eccDNA gene density. Mapping to 15 known herbicide-resistant QTL regions showed that the eccDNA coding sequences matched twelve, with four QTL matching HS coding sequences; only one region contained HR coding sequences. These findings establish that, like other pernicious weeds, blackgrass has eccDNAs that contain homologs of chromosomal genes, and these may contribute genetic heterogeneity and evolutionary innovation to rapidly adapt to abiotic stresses, including herbicide treatment.

Genome-wide identification of GH9 gene family and the assessment of its role during fruit abscission zone formation in Vaccinium ashei

KEY MESSAGE

The genomic location and stage-specific expression pattern of GH9 genes reveal their critical roles during fruit abscission zone formation in Vaccinium ashei. Glycosyl hydrolase family 9 (GH9) cellulases play a crucial role in both cellulose synthesis and hydrolysis during plant growth and development. Despite this importance, there is currently no study on the involvement of GH9-encoding genes, specifically VaGH9s, in abscission zone formation of rabbiteye blueberries (Vaccinium ashei). In this study, we identified a total of 61 VaGH9s in the genome, which can be classified into 3 subclasses based on conserved motifs and domains, gene structures, and phylogenetic analyses. Our synteny analysis revealed that VaGH9s are more closely related to the GH9s of Populus L. than to those of Arabidopsis, Vitis vinifera, and Citrus sinensis. In silico structural analysis predicted that most of VaGH9s are hydrophilic, and localized in cell membrane and/or cell wall, and the variable sets of cis-acting regulatory elements and functional diversity with four categories of stress response, hormone regulation, growth and development, and transcription factor-related elements are present in the promoter sequence of VaGH9s genes. Transcriptomic analysis showed that there were 22 differentially expressed VaGH9s in fruit abscission zone tissue at the veraison stage, and the expression of VaGH9B2 and VaGH9C10 was continuously increased during fruit maturation, which were in parallel with the increasing levels of cellulase activity and oxidative stress indicators, suggesting that they are involved in the separation stage of fruit abscission in Vaccinium ashei. Our work identified 22 VaGH9s potentially involved in different stages of fruit abscission and would aid further investigation into the molecular regulation of abscission in rabbiteye blueberries fruit.

A multi-level approach reveals key physiological and molecular traits in the response of two rice genotypes subjected to water deficit at the reproductive stage

Rice is more vulnerable to drought than maize, wheat, and sorghum because its water requirements remain high throughout the rice life cycle. The effects of drought vary depending on the timing, intensity, and duration of the events, as well as on the rice genotype and developmental stage. It can affect all levels of organization, from genes to the cells, tissues, and/or organs. In this study, a moderate water deficit was applied to two contrasting rice genotypes, IAC 25 and CIRAD 409, during their reproductive stage. Multi-level transcriptomic, metabolomic, physiological, and morphological analyses were performed to investigate the complex traits involved in their response to drought. Weighted gene network correlation analysis was used to identify the specific molecular mechanisms regulated by each genotype, and the correlations between gene networks and phenotypic traits. A holistic analysis of all the data provided a deeper understanding of the specific mechanisms regulated by each genotype, and enabled the identification of gene markers. Under non-limiting water conditions, CIRAD 409 had a denser shoot, but shoot growth was slower despite better photosynthetic performance. Under water deficit, CIRAD 409 was weakly affected regardless of the plant level analyzed. In contrast, IAC 25 had reduced growth and reproductive development. It regulated transcriptomic and metabolic activities at a high level, and activated a complex gene regulatory network involved in growth-limiting processes. By comparing two contrasting genotypes, the present study identified the regulation of some fundamental processes and gene markers, that drive rice development, and influence its response to water deficit, in particular, the importance of the biosynthetic and regulatory pathways for cell wall metabolism. These key processes determine the biological and mechanical properties of the cell wall and thus influence plant development, organ expansion, and turgor maintenance under water deficit. Our results also question the genericity of the antagonism between morphogenesis and organogenesis observed in the two genotypes.

MIR159 regulates multiple aspects of stamen and carpel development and requires dissection and delimitation of differential downstream regulatory network for manipulating fertility traits

Unravelling genetic networks regulating developmental programs are key to devising and implementing genomics assisted trait modification strategies. It is crucial to understand the role of small RNAs, and the basis of their ability to modify traits. MIR159 has been previously reported to cause defects in anther development in Arabidopsis; however, the complete spectrum and basis of the defects remained unclear. The present study was therefore undertaken to comprehensively investigate the role of miR159 from Brassica juncea in modulating vegetative and reproductive traits. Owing to the polyploid nature of Brassica, paralogous and homeologous copies of MIR159A, MIR159B, and, MIR159C were identified and analysis of the precursor uncovered extensive structural and sequence variation. The MIR159 locus with mature miR159 with perfect target complimentarily with MYB65, was cloned from Brassica juncea var. Varuna for functional characterization by generating constitutively over-expressing lines in Arabidopsis thaliana Col-0. Apart from statistically significant difference in multiple vegetative traits, drastic differences were observed in stamen and pistil. Over-expression of miR159a led to shortening of filament length and loss of tetradynamous condition. Anthers were apiculate, with improper lobe formation, and unsynchronized cellular growth between connective tissue and another lobe development. Analysis revealed arrested meiosis/cytokinesis in microspores, and altered lignin deposition pattern in endothecial walls thus affecting anther dehiscence. In the gynoecium, flaccid, dry stigmatic papillae, and large embryo sac in the female gametophyte was observed. Over-expression of miR159a thus severely affected pollination and seed-set. Analysis of the transcriptome data revealed components of regulatory networks of anther and carpel developmental pathway, and lignin metabolism that are affected. Expression analysis allowed us to position the miR159a-MYB65 module in the genetic network of stamen development, involved in pollen-grain maturation; in GA-mediated regulation of stamen development, and in lignin metabolism. The study, on one hand indicates role of miR159a-MYB65 in regulating multiple aspects of reproductive organ development that can be manipulated for trait modification, but also raises several unaddressed questions such as relationship between miR159a and male-meiosis, miR159a and filament elongation for future investigations. Accession numbers: KC204951-KC204960. Project number PRJNA1035268.

Supplementary Information

The online version contains supplementary material available at 10.1007/s12298-023-01377-7.

Function of Transcription Factors PoMYB12, PoMYB15, and PoMYB20 in Heat Stress and Growth of Pleurotus ostreatus

MYB transcription factors (TFs) have been extensively studied in plant abiotic stress responses and growth and development. However, the role of MYB TFs in the heat stress response and growth and development of Pleurotus ostreatus remains unclear. To investigate the function of PoMYB12, PoMYB15, and PoMYB20 TFs in P. ostreatus, mutant strains of PoMYB12, PoMYB15, and PoMYB20 were generated using RNA interference (RNAi) and overexpression (OE) techniques. The results indicated that the mycelia of OE-PoMYB12, OE-PoMYB20, and RNAi-PoMYB15 mutant strains exhibited positive effects under heat stress at 32 °C, 36 °C, and 40 °C. Compared to wild-type strains, the OE-PoMYB12, OE-PoMYB20, and RNAi-PoMYB15 mutant strains promoted the growth and development of P. ostreatus. These mutant strains also facilitated the recovery of growth and development of P. ostreatus after 24 h of 36 °C heat stress. In conclusion, the expression of PoMYB12 and PoMYB20 supports the mycelium's response to heat stress and enhances the growth and development of P. ostreatus, whereas PoMYB15 produces the opposite effect.

The ARF2-MYB6 module mediates auxin-regulated petal expansion in rose

In cut rose (Rosa hybrida), the flower-opening process is closely associated with vase life. Auxin induces the expression of transcription factor genes that function in petal growth via cell expansion. However, the molecular mechanisms underlying the auxin effect during flower opening are not well understood. Here, we identified the auxin-inducible transcription factor gene RhMYB6, whose expression level is high during the early stages of flower opening. Silencing of RhMYB6 delayed flower opening by controlling petal cell expansion through down-regulation of cell expansion-related genes. Furthermore, we demonstrated that the auxin response factor RhARF2 directly interacts with the promoter of RhMYB6 and represses its transcription. Silencing of RhARF2 resulted in larger petal size and delayed petal movement. We also showed that the expression of genes related to ethylene and petal movement showed substantial differences in RhARF2-silenced petals. Our results indicate that auxin-regulated RhARF2 is a critical player that controls flower opening by governing RhMYB6 expression and mediating the crosstalk between auxin and ethylene signaling.

Seed Halopriming: A Promising Strategy to Induce Salt Tolerance in Indonesian Pigmented Rice

Unfavorable environmental conditions and climate change impose stress on plants, causing yield losses worldwide. The Indonesian pigmented rice (Oryza sativa L.) cultivars Cempo Ireng Pendek (black rice) and Merah Kalimantan Selatan (red rice) are becoming popular functional foods due to their high anthocyanin contents and have great potential for widespread cultivation. However, their ability to grow on marginal, high-salinity lands is limited. In this study, we investigated whether seed halopriming enhances salt tolerance in the two pigmented rice cultivars. The non-pigmented cultivars IR64, a salt-stress-sensitive cultivar, and INPARI 35, a salt tolerant, were used as control. We pre-treated seeds with a halopriming solution before germination and then exposed the plants to a salt stress of 150 mM NaCl at 21 days after germination using a hydroponic system in a greenhouse. Halopriming was able to mitigate the negative effects of salinity on plant growth, including suppressing reactive oxygen species accumulation, increasing the membrane stability index (up to two-fold), and maintaining photosynthetic pigment contents. Halopriming had different effects on the accumulation of proline, in different rice varieties: the proline content increased in IR64 and Cempo Ireng Pendek but decreased in INPARI 35 and Merah Kalimantan Selatan. Halopriming also had disparate effects in the expression of stress-related genes: OsMYB91 expression was positively correlated with salt treatment, whereas OsWRKY42 and OsWRKY70 expression was negatively correlated with this treatment. These findings highlighted the potential benefits of halopriming in salt-affected agro-ecosystems.

Insights into the molecular mechanisms underlying responses of apple trees to abiotic stresses

Apple (Malus[Formula: see text]domestica) is a popular temperate fruit crop worldwide. However, its growth, productivity, and quality are often adversely affected by abiotic stresses such as drought, extreme temperature, and high salinity. Due to the long juvenile phase and highly heterozygous genome, the conventional breeding approaches for stress-tolerant cultivars are time-consuming and resource-intensive. These issues may be resolved by feasible molecular breeding techniques for apples, such as gene editing and marker-assisted selection. Therefore, it is necessary to acquire a more comprehensive comprehension of the molecular mechanisms underpinning apples' response to abiotic stress. In this review, we summarize the latest research progress in the molecular response of apples to abiotic stressors, including the gene expression regulation, protein modifications, and epigenetic modifications. We also provide updates on new approaches for improving apple abiotic stress tolerance, while discussing current challenges and future perspectives for apple molecular breeding.

Haplotype-resolved genomes of wild octoploid progenitors illuminate genomic diversifications from wild relatives to cultivated strawberry

Strawberry is an emerging model for studying polyploid genome evolution and rapid domestication of fruit crops. Here we report haplotype-resolved genomes of two wild octoploids (Fragaria chiloensis and Fragaria virginiana), the progenitor species of cultivated strawberry. Substantial variation is identified between species and between haplotypes. We redefine the four subgenomes and track the genetic contributions of diploid species by additional sequencing of the diploid F. nipponica genome. We provide multiple lines of evidence that F. vesca and F. iinumae, rather than other described extant species, are the closest living relatives of these wild and cultivated octoploids. In response to coexistence with quadruplicate gene copies, the octoploid strawberries have experienced subgenome dominance, homoeologous exchanges and coordinated expression of homoeologous genes. However, some homoeologues have substantially altered expression bias after speciation and during domestication. These findings enhance our understanding of the origin, genome evolution and domestication of strawberries.

Metabolomic and transcriptomice analyses of flavonoid biosynthesis in apricot fruits

Introduction

Flavonoids, as secondary metabolites in plants, play important roles in many biological processes and responses to environmental factors.

Methods

Apricot fruits are rich in flavonoid compounds, and in this study, we performed a combined metabolomic and transcriptomic analysis of orange flesh (JN) and white flesh (ZS) apricot fruits.

Results and discussion

A total of 222 differentially accumulated flavonoids (DAFs) and 15855 differentially expressed genes (DEGs) involved in flavonoid biosynthesis were identified. The biosynthesis of flavonoids in apricot fruit may be regulated by 17 enzyme-encoding genes, namely PAL (2), 4CL (9), C4H (1), HCT (15), C3'H (4), CHS (2), CHI (3), F3H (1), F3'H (CYP75B1) (2), F3'5'H (4), DFR (4), LAR (1), FLS (3), ANS (9), ANR (2), UGT79B1 (6) and CYP81E (2). A structural gene-transcription factor (TF) correlation analysis yielded 3 TFs (2 bHLH, 1 MYB) highly correlated with 2 structural genes. In addition, we obtained 26 candidate genes involved in the biosynthesis of 8 differentially accumulated flavonoids metabolites in ZS by weighted gene coexpression network analysis. The candidate genes and transcription factors identified in this study will provide a highly valuable molecular basis for the in-depth study of flavonoid biosynthesis in apricot fruits.

DREB1 and DREB2 Genes in Garlic (Allium sativum L.): Genome-Wide Identification, Characterization, and Stress Response

Dehydration-responsive element-binding (DREB) transcription factors (TFs) of the A1 and A2 subfamilies involved in plant stress responses have not yet been reported in Allium species. In this study, we used bioinformatics and comparative transcriptomics to identify and characterize DREB A1 and A2 genes redundant in garlic (Allium sativum L.) and analyze their expression in A. sativum cultivars differing in the sensitivity to cold and Fusarium infection. Eight A1 (AsaDREB1.1-1.8) and eight A2 (AsaDREB2.1-2.8) genes were identified. AsaDREB1.1-1.8 genes located in tandem on chromosome 1 had similar expression patterns, suggesting functional redundancy. AsaDREB2.1-2.8 were scattered on different chromosomes and had organ- and genotype-specific expressions. AsaDREB1 and AsaDREB2 promoters contained 7 and 9 hormone- and stress-responsive cis-regulatory elements, respectively, and 13 sites associated with TF binding and plant development. In both Fusarium-resistant and -sensitive cultivars, fungal infection upregulated the AsaDREB1.1-1.5, 1.8, 2.2, 2.6, and 2.8 genes and downregulated AsaDREB2.5, but the magnitude of response depended on the infection susceptibility of the cultivar. Cold exposure strongly upregulated the AsaDREB1 genes, but downregulated most AsaDREB2 genes. Our results provide the foundation for further functional analysis of the DREB TFs in Allium crops and could contribute to the breeding of stress-tolerant varieties.

Physiological response and transcriptome analyses of leguminous Indigofera bungeana Walp. to drought stress

Objective

Indigofera bungeana is a shrub with high quality protein that has been widely utilized for forage grass in the semi-arid regions of China. This study aimed to enrich the currently available knowledge and clarify the detailed drought stress regulatory mechanisms in I. bungeana, and provide a theoretical foundation for the cultivation and resistance breeding of forage crops.

Methods

This study evaluates the response mechanism to drought stress by exploiting multiple parameters and transcriptomic analyses of a 1-year-old seedlings of I. bungeana in a pot experiment.

Results

Drought stress significantly caused physiological changes in I. bungeana. The antioxidant enzyme activities and osmoregulation substance content of I. bungeana showed an increase under drought. Moreover, 3,978 and 6,923 differentially expressed genes were approved by transcriptome in leaves and roots. The transcription factors, hormone signal transduction, carbohydrate metabolism of regulatory network were observed to have increased. In both tissues, genes related to plant hormone signaling transduction pathway might play a more pivotal role in drought tolerance. Transcription factors families like basic helix-loop-helix (bHLH), vian myeloblastosis viral oncogene homolog (MYB), basic leucine zipper (bZIP) and the metabolic pathway related-genes like serine/threonine-phosphatase 2C (PP2C), SNF1-related protein kinase 2 (SnRK2), indole-3-acetic acid (IAA), auxin (AUX28), small auxin up-regulated rna (SAUR), sucrose synthase (SUS), sucrosecarriers (SUC) were highlighted for future research about drought stress resistance in Indigofera bungeana.

Conclusion

Our study posited I. bungeana mainly participate in various physiological and metabolic activities to response severe drought stress, by regulating the expression of the related genes in hormone signal transduction. These findings, which may be valuable for drought resistance breeding, and to clarify the drought stress regulatory mechanisms of I. bungeana and other plants.

The pivotal role of MYB transcription factors in plant disease resistance

MAIN CONCLUSION

MYB transcription factors are essential for diverse biology processes in plants. This review has focused on the potential molecular actions of MYB transcription factors in plant immunity. Plants possess a variety of molecules to defend against disease. Transcription factors (TFs) serve as gene connections in the regulatory networks controlling plant growth and defense against various stressors. As one of the largest TF families in plants, MYB TFs coordinate molecular players that modulate plant defense resistance. However, the molecular action of MYB TFs in plant disease resistance lacks a systematic analysis and summary. Here, we describe the structure and function of the MYB family in the plant immune response. Functional characterization revealed that MYB TFs often function either as positive or negative modulators towards different biotic stressors. Moreover, the MYB TF resistance mechanisms are diverse. The potential molecular actions of MYB TFs are being analyzed to uncover functions by controlling the expression of resistance genes, lignin/flavonoids/cuticular wax biosynthesis, polysaccharide signaling, hormone defense signaling, and the hypersensitivity response. MYB TFs have a variety of regulatory modes that fulfill pivotal roles in plant immunity. MYB TFs regulate the expression of multiple defense genes and are, therefore, important for increasing plant disease resistance and promoting agricultural production.