Signal transduction during cold, salt, and drought stresses in plants

CsABF8 mediates drought-induced ABA signaling in the regulation of raffinose biosynthesis in Camellia sinensis leaves

Drought has become an important environmental stress limiting the growth and development of Camellia sinensis due to its moisture-loving and temperature-tolerant nature. ABA-response element binding factor (ABFs) is a key transcriptional regulator in the ABA signaling pathway that regulates plant responses to hormones and adversity. However, their roles and regulatory mechanisms in tea tree remain unknown. To investigate the drought response in Camellia sinensis, drought-sensitive (Fuyun No.6, FY) and drought-tolerant (Taicha No.12, TC) tea cultivars were treated with exogenous PEG and ABA and subjected to non-targeted metabolomics by Ultra Performance Liquid Chromatography-Electrospray Ionization-Triple Quadrupole tandem Mass Spectrometry (UPLC/ESI-Q TRAP-MS/MS). The bioactive carbohydrates galactinol and raffinose were identified as potential drought regulators. Analysis of transcriptomics data identified potential drought tolerant target genes, namely CsGolS1/2, encoding galactinol synthases, CsRaf6, a raffinose synthase, and CsABF8, a transcriptional regulator in the ABA-response element binding factor family. The tea CsSnRK2.8-CsABF8-CsGolS1/CsGolS2/CsRaf6 regulatory module induced in response to drought stress was constructed using multiple molecular validation tools. This preliminary analysis of the molecular mechanism by which CsABF8, a regulator on the ABA signaling pathway, mediates the differences in drought tolerance in different tea cultivars provides a theoretical basis for the selection and breeding of drought-resistant varieties.

Methyl jasmonate-loaded chitosan nanoparticles improve tea drought resistance on drought-sensitive cultivar 'Zhongcha 108'

DS severely impacts tea plant growth and yield. Foliar application of Methyl jasmonate (MJ) -loaded Chitosan nanoparticles (CNPs) (MJ-CNPs) significantly boost tea DS resistance, necessitating further mechanism exploration. This study comprehensively investigated alterations at the phenotypic, biochemical, and genetic levels. Relative water content, total pigment content, and soluble proteins decreased, while soluble sugar increased significantly under DS and with apparent recovery after MJ-CNPs treatment. Catechins exhibited a significant decrease under DS, especially EGCG (24.6 to 13.4 mg•g-1), but were absolutely mitigated by treatment. Antioxidant capacities (DPPH, FRAP, ABTS, and SOA) showed a further improvement by MJ-CNPs treatment. Endogenous ABA and SA increased under DS, further elevated by MJ-CNPs. CsNCED, CsPYL8, CsPP2C, CsMYB, and CsABF genes involved in ABA-dependent pathways were confirmed with promoted expressions by foliar pre-treatment. The CsJAZ and CsMYC2 gene family which involved in the jasmonic acid (JA) pathway, displayed varied expression patterns. The integration of metabolite and gene expression levels provided a comprehensive illustration of tea DS tolerance mechanism and offered promising promotion strategies through foliar application of MJ-CNPs.

Arabidopsis CIRP1 E3 ligase modulates drought and oxidative stress tolerance and reactive oxygen species homeostasis by directly degrading catalases

Reactive oxygen species (ROS) plays critical roles in modulating plant growth and stress response and its homeostasis is fine tuned using multiple peroxidases. H2O2, a major kind of ROS, is removed rapidly and directly using three catalases, CAT1, CAT2, and CAT3, in Arabidopsis. Although the activity regulations of catalases have been well studied, their degradation pathway is less clear. Here, we report that CAT2 and CAT3 protein abundance was partially controlled using the 26S proteasome. To further identify candidate proteins that modulate the stability of CAT2, we performed yeast-two-hybrid screening and recovered several clones encoding a protein with RING and vWA domains, CIRP1 ( CAT2 Interacting RING Protein 1). Drought and oxidative stress downregulated CIRP1 transcripts. CIRP1 harbored E3 ubiquitination activity and accelerated the degradation of CAT2 and CAT3 by direct interaction and ubiquitination. The cirp1 mutants exhibited stronger drought and oxidative stress tolerance, which was opposite to the cat2 and cat3 mutants. Genetic analysis revealed that CIRP1 acts upstream of CAT2 and CAT3 to negatively regulate drought and oxidative stress tolerance. The increased drought and oxidative stress tolerance of the cirp1 mutants was due to enhanced catalase (CAT) activities and alleviated ROS levels. Our data revealed that the CIRP1-CAT2/CAT3 module plays a vital role in alleviating ROS levels and balancing growth and stress responses in Arabidopsis.

Drought Stress in Roses: A Comprehensive Review of Morphophysiological, Biochemical, and Molecular Responses

Climate change poses significant threats to agriculture globally, particularly in arid and semi-arid regions where drought stress (DS) is most severe, disrupting ecosystems and constraining progress in agriculture and horticulture. Roses, valued for their aesthetic appeal, are highly susceptible to abiotic stresses, especially DS, which markedly reduces flower quantity and quality. Under DS conditions, roses exhibit diverse morphological, physiological, biochemical, and molecular adaptations that vary across species. This review examines the effects of DS on rose growth, yield, and physiological traits, including gas exchange, photosynthesis, phytohormone dynamics, and water and nutrient relationships, alongside their biochemical and molecular responses. Furthermore, DS impacts the biosynthesis of secondary metabolites, notably reducing the yield and quality of essential oils in roses, which are critical for their commercial value in perfumery and aromatherapy. Additionally, the impact of DS on rose flower quality and post-harvest longevity is assessed. By elucidating these diverse responses, this review provides a framework for understanding DS effects on roses and offers insights to develop strategies for mitigating its adverse impacts.

Genome-wide identification of GmEDS1 gene family members in soybean and expression analysis in response to biotic and abiotic stresses

Enhanced Disease Susceptibility 1 (EDS1), a key regulator in plant defense responses, plays central roles in resistance to stresses. Therefore, the identification and characterization of soybean GmEDS1 family genes and verification of how these genes are associated with stresses are the focus of this study. We identified 11 GmEDS1 genes, which all have lipase-like and EP (EDS1-PAD4-specific) conserved domains, they are unevenly distributed across six chromosomes, including tandem repetitions. Whole-genome duplication and segmental duplication events were the main reason for GmEDS1 family expansion, and the family underwent purification selection during evolution. We detected 25 types of cis-regulatory elements, which enable GmEDS1s to respond to multiple signals. GmEDS1s are rapidly and strongly induced by drought, salt, the common cutworm, and soybean mosaic virus, indicating that they have important biological functions in coping with both abiotic and biological stresses. Furthermore, the expression levels of GmEDS1s differed between long-day and short-day conditions: it was very low under short-day conditions, which may increase the sensitivity of soybean to pathogens under short-day conditions. Overall, this study identified and characterized the members of the GmEDS1 gene family in the soybean genome, and determined that GmEDS1s respond to both abiotic and biotic stresses, providing new key genes for soybean breeders.

MdWRKY71 positively regulates drought tolerance in apple plants by interplaying with MdARF3 and promoting superoxide dismutase biosynthesis

With the ongoing rise in global temperatures, drought stress has become a significant threat to the normal growth and development of horticultural crops. Identifying the regulatory genes is the key to genetic improvement. Extensive research has highlighted the pivotal role of WRKY transcription factors in orchestrating plant responses to both biotic and abiotic stresses. However, their precise involvement in drought tolerance and the related molecular mechanisms have yet to be fully elucidated. In this study, we demonstrated that MdWRKY71 functioned as a positive regulator of drought tolerance in apple. Overexpressing MdWRKY71 in apple improved drought tolerance, while silencing it had the opposite effect. Additionally, under drought stress, compared with the control, chlorophyll fluorescence values, superoxide dismutase (SOD), and peroxidase levels were elevated in MdWRKY71-overexpressing apple and tobacco transgenic materials. Interaction analysis showed that MdWRKY71 directly binds to the W-box element of the MdFeSOD promoter and activates its transcription. We used yeast two-hybrid screening to identify potential interactors of MdWRKY71 and confirmed the interaction between MdWRKY71 and MdARF3 using Pull-down, bimolecular fluorescence complementation, and luciferase complementation imaging assays. Interestingly, MdARF3 enhanced MdWRKY71-mediated transcriptional activation of MdFeSOD through their interaction. In summary, our findings revealed that the MdWRKY71-MdARF3 module synergistically upregulates the expression of MdFeSOD and SOD enzyme activity in response to drought stress. This research uncovers a new mechanism of plant drought tolerance and presents a feasible strategy to enhance plant drought tolerance through stabilizing the biosynthesis of superoxide dismutase.

Comprehensive co-expression network reveals the fine-tuning of AsHSFA2c in balancing drought tolerance and growth in oat

Persistent activation of drought tolerance is detrimental to plant growth and development. However, the mechanism that balances plant drought tolerance and growth remains largely undetermined. Here, we constructed a comprehensive co-expression network comprising 84 transcriptome datasets associated with growth and drought tolerance in oats. Moreover, 84 functional modules and many candidate genes related to drought tolerance and growth were identified. A key candidate gene, AsHSFA2c was involved in fine-tuning the balance between drought tolerance and growth by inhibiting plant growth and positively regulating drought tolerance. Then, we determined AsDOF25 as an upstream positive regulator and AsAGO1 as the downstream target gene of AsHSFA2c. These results imply that the AsDOF25-AsHSFA2c-AsAGO1 module contributes to the balance between drought tolerance and growth in oats. Our findings and resources will facilitate the identification of key genes related to drought tolerance and further studies of the genetic basis underlying strong drought tolerance in oats.

Regulatory networks of bZIPs in drought, salt and cold stress response and signaling

Abiotic stresses adversely impact plants survival and growth, which in turn affect plants especially crop yields worldwide. To cope with these stresses, plant responses depend on the activation of molecular networks cascades, including stress perception, signal transduction, and the expression of specific stress-related genes. Plant bZIP (basic leucine zipper) transcription factors are important regulators that respond to diverse abiotic stresses.By binding to specific cis-elements, bZIPs can control the transcription of target genes, giving plants stress resistance. This review describes the structural characteristics of bZIPs and summarizes recent progress in analyzing the molecular mechanisms regulating plant responses to salinity, drought, and cold in different plant species. The main goal is to deepen the understanding of bZIPs and explore their value in genetic improvement of plants.

GmRPN11d positively regulates plant salinity tolerance by improving protein stability through SUMOylation

The 26S proteasome is a crucial protease complex responsible for degrading specific proteins to maintain cellular function during salt stress. Previous studies have shown that GmRPN11d, a subunit of the regulatory particle in soybean, is upregulated in response to short-term salt stress. This research discovered that GmRPN11d is localized in the nucleus and cytoplasm, with its expression increasing under high salinity and other stress conditions. Overexpressing GmRPN11d in Arabidopsis and soybean hairy roots significantly improves salt stress tolerance. Examination of physiological indices and expression patterns of salt-responsive marker genes reveals that overexpression of GmRPN11d enhances the ability to scavenge reactive oxygen species, regulates ion balance, exhibits hypersensitivity to ABA, and activates the ABA signaling pathway under salt stress. Additionally, GmRPN11d was demonstrated to interact with the SUMO E3 ligase GmMMS21 in both in vivo and in vitro experiments. This interaction serves to facilitate the SUMOylation of GmRPN11d, ultimately contributing to its stability when faced with salt stress. Taken together, these findings highlight the role of GmRPN11d in promoting plant salt tolerance through SUMOylation, mediated by GmMMS21. This study provides valuable insights into modifying the 26S proteasome subunit in soybean, offering a potential target gene for developing genetically modified salt-resistant crops.

The Mulberry WRKY Transcription Factor MaWRKYIIc7 Participates in Regulating Plant Drought Stress Tolerance

The sericulture industry is an important component of the agricultural industry. Drought stress can cause yellowing, premature ageing, and the shrinkage of mulberry (Morus alba L.) leaves, greatly damaging their quality and restricting the high-quality development of the sericulture industry. WRKY transcription factors play important roles in the plant drought stress response. In this study, we found that MaWRKYIIc7 of the mulberry WRKY TFs, had significantly higher expression levels in leaves than in other tissues and was induced to be expressed under drought stress. The MaWRKYIIc7 protein is located in the nucleus and plasma membrane, and its transcriptional activity depends mainly on the N-terminal sequence. The overexpression of MaWRKYIIc7 in Arabidopsis resulted in better drought tolerance. An analysis of the transient overexpression of MaWRKYIIc7 in mulberry seedlings under drought stress revealed that the transgenic seedlings presented decreased stomatal opening, decreased MDA content, increased ROS clearance ability, and increased the expression of ABA biosynthesis-related genes. The Y1H and Dual-luc results indicate that MaWRKYIIc7 can bind W-boxes to positively regulate MaNCED1 and MaRD29A, synergistically regulating the drought tolerance of mulberry. Overall, our research suggests that MaWRKYIIc7 can increase plant drought tolerance by promoting ROS clearance, adjusting stomatal opening, and activating the ABA signalling pathway.

Differential expression and localization of expansins in Arabidopsis shoots: implications for cell wall dynamics and drought tolerance

Expansins are cell wall-modifying proteins implicated in plant growth and stress responses. In this study, we explored the differential localization of expansins in Arabidopsis thaliana shoots, with a focus on EXPA1, EXPA10, EXPA14, and EXPA15 utilizing pEXPA::EXPA translational fusion lines. Employing the chemically inducible system pOp6/LhGR for EXPA1 overexpression and high-throughput automatic phenotyping we evaluated the drought response and photosynthetic efficiency under stress conditions. We observed distinct expression patterns of expansins, with EXPA1 primarily localized in stomatal guard cells, while EXPA10 and EXPA15 showed strong cell wall (CW) localization in epidermal and other tissues. Overexpression of EXPA1 resulted in pronounced changes in CW-related gene expression, particularly during early stages of induction, including the upregulation of other expansins and CW-modifying enzymes. The induced EXPA1 line also displayed significant morphological changes in shoots, including smaller plant size, delayed senescence, and structural alterations in vascular tissues. Additionally, EXPA1 overexpression conferred drought tolerance, as evidenced by enhanced photosynthetic efficiency (Fv/FM), and low steady-state non-photochemical quenching (NPQ) values under drought stress. These findings highlight the critical role of EXPA1 in regulating plant growth, development, and stress response, with potential applications in improving drought tolerance in crops.

Regulatory mechanism analysis of signal transduction genes during rapeseed (Brassica napus L.) germination under aluminum stress using WGCNA combination with QTL

As soil becomes more acidic, aluminum toxicity has emerged as a key issue impacting seed germination and crop productivity in such environments. Therefore, it is urgent to investigate the mechanism of the influence of aluminum stress on germination. In this study, we focused on one of the major bioenergy crops-rapeseed. Seeds of aluminum-sensitive (S) and aluminum-resistant (R) lines screened from the recombinant inbred lines (RILs) population of rapeseed were treated with 80 µg·ml-1 AlCl3 (ST, RT). Purified water served as the control (SC, RC). On the 3rd, 5th, and 7th day after treatment, the root tissue was collected for transcriptome sequencing. Utilizing MapMan software, the genes showing differential expression in S and R lines were assigned to the aluminum stress signaling pathway, resulting in the identification of 1036 genes. By weighted gene co-expression network analysis (WGCNA), five co-expressed gene modules associated with aluminum stress were discovered. A total of 332 candidate genes were screened by combining the genes related to aluminum stress signal transduction pathways with the module hub genes. Among them, 26 key genes were located in quantitative trait loci (QTL) with confidence intervals for germination-related traits of rapeseed under aluminum stress, and primarily distributed in 11 QTL regions, such as qRDW-A09-1, qRDW-A10-1 and qRGV-A01-2, they were associated with relative root length (RRL), relative root dry weight (RDW), relative germination vigor (RGV) and relative bud length (RBL). The roles included transcription regulation, stress protein production, redox processes, hormone signaling, cell wall alteration, and calcium-based signal transmission. Compared with the R line, the S line exhibited quicker and stronger activation of genes related to aluminum stress signal transduction, suggesting that the S line was more responsive to aluminum stress. This research offers an empirical basis for identifying aluminum-resistant rapeseed varieties and investigating the molecular regulation of aluminum tolerance during germination.

Overexpression of Suaeda salsa SsDHN Gene Enhances Salt Resistance in Tobacco by Improving Photosynthetic Characteristics and Antioxidant Activity

Salt stress is a major abiotic stress that interferes with plant growth and affects crop production. Dehydrin (DHN), a member of the late embryogenesis abundant (LEA) protein family, was considered to be a stress protein involved in the protective reaction of plant dehydration. Our previous research has shown that overexpression of the Suaeda salsa SsDHN gene enhances tolerance to salt stress in tobacco. However, the research on its protection in photosynthesis under salt stress remains unclear. In this study, gene overexpression (SsDHN-OE) tobacco plants were utilized to study the effect of the SsDHN gene on plant photosynthesis under salt stress. Our findings showed that overexpression of SsDHN increased the biomass, leaf area, root length, and root surface area in tobacco seedlings under salt stress conditions. The transgenic tobacco with overexpression of SsDHN had obvious stomatal closure, which effectively alleviated the adverse effects of salt stress on photosynthetic efficiency. Overexpression of the SsDHN gene in tobacco can effectively reduce the degree of photoinhibition and chloroplast damage caused by salt stress. Moreover, the SsDHN-overexpressing transgenic tobacco plants exhibited a decrease in oxidative damage and protected membrane structures related to photosynthesis by increasing antioxidant enzyme activity and antioxidant substance content. It was further found that the expression levels of photosynthetic and antioxidant-related genes Rubisco, SBPase, POD7, CAT3, APX2, and SOD3 were significantly up-regulated by overexpressing the SsDHN gene in tobacco seedlings under salt stress. In conclusion, the SsDHN gene might improve the salt stress resistance of tobacco seedlings and be involved in regulating photosynthesis and antioxidant activity under salt stress.

Molecular and Physiological Responses of Plants that Enhance Cold Tolerance

Low-temperature stress, including chilling and freezing injuries, significantly impacts plant growth in tropical and temperate regions. Plants respond to cold stress by activating mechanisms that enhance freezing tolerance, such as regulating photosynthesis, metabolism, and protein pathways and producing osmotic regulators and antioxidants. Membrane stability is crucial, with cold-resistant plants exhibiting higher lipid unsaturation to maintain fluidity and normal metabolism. Low temperatures disrupt reactive oxygen species (ROS) metabolism, leading to oxidative damage, which is mitigated by antioxidant defenses. Hormonal regulation, involving ABA, auxin, gibberellins, and others, further supports cold adaptation. Plants also manage osmotic balance by accumulating osmotic regulators like proline and sugars. Through complex regulatory pathways, including the ICE1-CBF-COR cascade, plants optimize gene expression to survive cold stress, ensuring adaptability to freezing conditions. This study reviews the recent advancements in genetic engineering technologies aimed at enhancing the cold resistance of agricultural crops. The goal is to provide insights for further improving plant cold tolerance and developing new cold-tolerant varieties.

Understanding the impacts of drought on peanuts (Arachis hypogaea L.): exploring physio-genetic mechanisms to develop drought-resilient peanut cultivars

Peanut is a vital source of protein, particularly in the tropical regions of Asian and African countries. About three-quarters of peanut production occurs worldwide in arid and semi-arid regions, making drought an important concern in peanut production. In the US about two-thirds of peanuts are grown in non-irrigated lands, where drought accounts for 50 million USD loss each year. The looming threat of climate change exacerbates this situation by increasing erratic rainfall. Drought not only reduces yield but also degrades product quality. Peanuts under drought stress exhibit higher levels of pre-harvest aflatoxin contamination, a toxic fungal metabolite detrimental to both humans and animals. One way to sustain peanut production in drought-prone regions and address pre-harvest aflatoxin contamination is by developing drought-tolerant peanut cultivars, a process that can be accelerated by understanding the underlying physiological and genetic mechanisms for tolerance to drought stress. Different physiological attributes and genetic regions have been identified in drought-tolerant cultivars that help them cope with drought stress. The advent of precise genetic studies, artificial intelligence, high-throughput phenotyping, bioinformatics, and data science have significantly improved drought studies in peanuts. Yet, breeding peanuts for drought tolerance is often a challenge as it is a complex trait significantly affected by environmental conditions. Besides technological advancements, the success of drought-tolerant cultivar development also relies on the identification of suitable germplasm and the conservation of peanut genetic variation.

Advances in the Structure, Function, and Regulatory Mechanism of Plant Plasma Membrane Intrinsic Proteins

Plasma membrane intrinsic proteins (PIPs), as members of the aquaporin (AQPs) family, can transport not only water but also urea, CO2, H2O2, metal ions, and trace elements. They are crucial for maintaining water balance, substance transport, and responding to various stresses. This article delves into the structure, function, response mechanism, molecular mechanism, and regulatory mechanism of PIPs as a result of biological and abiotic stresses. It also summarizes current research trends surrounding PIPs and highlights potential research directions for further exploration. The aim is to assist researchers in related fields in gaining a more comprehensive understanding and precise insight into the advancements in PIP research.

TRX h2-PP2AC2 module serves as a convergence node for aluminum stress and leaf senescence signals, regulating cell death via ABA-mediated ROS pathway

ROS/redox signaling plays an important role in the regulation of signal transduction and acclimation pathways activated by multiple abiotic stresses and leaf senescence. However, the regulatory events that produce ROS under different stimuli are far from clear. Here, we report the elucidation of the molecular mechanism of an h type thioredoxin, AhTRX h2, positively regulates Al sensitivity and leaf senescence by promoting ROS. AhTRX h2 transcript levels increased greatly during both natural senescence and Al stress condition in peanut. Ectopic expression of AhTRX h2 in Arabidopsis conferred Al sensitivity as well as premature leaf senescence, manifested by multiple indices, including inhibiting root elongation, severe cell death, and accelerated expression of MC1 and CEX17. AhTRX h2 exhibited similar functions to AtTRX h2, as AhTRX h2 was able to restore the phenotypes of the AtTRX h2 defective mutant (trxh2-4) which showed Al tolerant and late senescence phenotypes. The knock down of AhTRX h2 markedly suppressed Al- and senescence-induced cell death in peanut. AhTRX h2 could recruit catalytic subunit of protein phosphatase 2A (PP2AC2) to form a stable complex. The interaction between AhTRX h2 and AtPP2AC2, as well as AhPP2AC2 and AtTRX h2 was also proved. Overexpression of AhPP2AC2 significantly enhanced Al sensitivity and leaf senescence in Arabidopsis. Protein stability assay revealed that AhTRX h2 was more stable during aging or aluminum stress. Moreover, PP2AC2 could greatly enhance the stability of AhTRX h2 in vivo. Consistent with these observations, overexpression of AhPP2AC2 effectively enhanced AhTRX h2-induced Al sensitivity and precocious leaf senescence. AhTRX h2 and AhPP2AC2 required ABA and ROS in response to cell death under Al stress and senescence, and it was evidence to suggest that ABA acted upstream of ROS in this process. Together, AhTRX h2 and AhPP2AC2 constitute a stable complex that promotes the accumulation of ABA and ROS, effectively regulate cell death. These findings suggest that TRX h2-PP2AC2-mediated pathway may be a widespread mechanism in regulating Al stress and leaf senescence.

Heat Shock Factor HSFA6b Mediates Mitochondrial Unfolded Protein Response in Arabidopsis thaliana

Mitochondria are important organelles in eukaryotes and are involved in various metabolic processes. Mitochondrial proteotoxic stress triggers the mitochondrial unfolded protein response (UPRmt) to restore mitochondrial protein homeostasis and maintain normal life activities. However, the regulatory mechanism of plant UPRmt remains to be revealed in Arabidopsis. Based on the fact that UPRmt activates heat shock protein (HSP) genes, we identified the heat shock transcription factor HSFA6b as a key regulator mediating UPRmt through reverse genetics. HSFA6b responded to mitochondrial proteotoxic stress and regulated mitochondrial heat shock proteins' genes' (mtHSPs) expression. HSFA6b translocated to the nuclear after treatment with doxycycline (Dox)-a mitochondrial ribosome translation inhibitor. HSFA6b binds to the mtHSPs promoters and activates mtHSPs expression. The HSFA6b mutation blocked the UPRmt signals to promote root growth under mitochondrial proteotoxic stress and accelerated leaf senescence during development. Our study reveals a novel signal-regulating mechanism in the UPRmt pathways and provides new insights regarding the regulation of plant growth and development and stress resistance by the UPRmt pathways.

A WUSCHEL-related homeobox transcription factor, SlWOX4, negatively regulates drought tolerance in tomato

KEY MESSAGE

CRISPR/Cas9-mediated knockout of SlWOX4 gene in tomato enhances tolerance to drought stress. Drought stress is one of the major abiotic factors that seriously affects plant growth and crop yield. WUSCHEL-related homeobox (WOX) transcription factors are involved in plant growth, development and stress response. However, little is known about the role of WOX genes in drought tolerance in tomato. Here, SlWOX4, a member of the WOX family in tomato, was functionally characterized in mediating drought tolerance. SlWOX4 was homologous to Nicotiana tabacum NtWOX4 with a conserved HD domain, and was localized in the nucleus. SlWOX4 was significantly down-regulated by drought and abscisic acid (ABA) treatments. The loss-of-function mutations of SlWOX4 produced using the CRISPR-Cas9 system in tomato improved drought tolerance by reducing water loss rate and enhancing stomatal closure. In addition, the wox4 lines exhibited reduced accumulation of reactive oxygen species (ROS) and malondialdehyde (MDA), increased antioxidant enzyme activity, proline contents and ABA contents under drought stress. Moreover, gene editing of SlWOX4 in tomato enhanced drought tolerance by regulating the expression of genes encoding antioxidants and ABA signaling molecules. In summary, SlWOX4 gene might negatively regulate drought stress tolerance in tomato and has great potential as a drought-resistant crop-breeding target genes.

Genome-Wide Characterization of the INDETERMINATE DOMAIN (IDD) Zinc Finger Gene Family in Solanum lycopersicum and the Functional Analysis of SlIDD15 in Shoot Gravitropism

The plant-specific IDD transcription factors (TFs) are vital for regulating plant growth and developmental processes. However, the characteristics and biological roles of the IDD gene family in tomato (Solanum lycopersicum) are still largely unexplored. In this study, 17 SlIDD genes were identified in the tomato genome and classified into seven subgroups according to the evolutionary relationships of IDD proteins. Analysis of exon-intron structures and conserved motifs reflected the evolutionary conservation of SlIDDs in tomato. Collinearity analysis revealed that segmental duplication promoted the expansion of the SlIDD family. Ka/Ks analysis indicated that SlIDD gene orthologs experienced predominantly purifying selection throughout evolution. The analysis of cis-acting elements revealed that the promoters of SlIDD genes contain numerous elements associated with light, plant hormones, and abiotic stresses. The RNA-seq data and qRT-PCR experimental results showed that the SlIDD genes exhibited tissue-specific expression. Additionally, Group A members from Arabidopsis thaliana and rice are known to play a role in regulating plant shoot gravitropism. QRT-PCR analysis confirmed that the expression level of SlIDD15 in Group A was high in the hypocotyls and stems. Subcellular localization demonstrated that the SlIDD15 protein was localized in the nucleus. Surprisingly, the loss-of-function of SlIDD15 by CRISPR/Cas9 gene editing technology did not display obvious gravitropic response defects, implying the existence of functional redundant factors within SlIDD15. Taken together, this study offers foundational insights into the tomato IDD gene family and serves as a valuable guide for exploring their molecular mechanisms in greater detail.

Alfin-like (AL) transcription factor family in Oryza sativa L.: Genome-wide analysis and expression profiling under different stresses

Oryza sativa L. is the world's most essential and economically important food crop. Climate change and ecological imbalances make rice plants vulnerable to abiotic and biotic stresses, threatening global food security. The Alfin-like (AL) transcription factor family plays a crucial role in plant development and stress responses. This study comprehensively analyzed this gene family and their expression profiles in rice, revealing nine AL genes, classifying them into three distinct groups based on phylogenetic analysis and identifying four segmental duplication events. RNA-seq data analysis revealed high expression levels of OsALs in different tissues, growth stages, and their responsiveness to stresses. RT-qPCR data showed significant expression of OsALs in different abiotic stresses. Identification of potential cis-regulatory elements in promoter regions has also unveiled their involvement. Tertiary structures of the proteins were predicted. These findings would lay the groundwork for future research to reveal their molecular mechanism in stress tolerance and plant development.

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.

Differential Gene Expression Responses to Salt and Drought Stress in Tall Fescue (Festuca arundinacea Schreb.)

Understanding gene expression kinetics and the underlying physiological mechanisms in stress combinations is a challenge for the purpose of stress resistance breeding. The novelty of this study is correlating the physiological mechanisms with the expression of key target genes in tall fescue under a combination of various salinity and osmotic stress treatments. Four drought- and salt-responsive genes belonging to different crucial pathways evaluated included one transcription factor FabZIP69, one for the cytosolic polyamine synthetase FaADC1, one for ABA signaling FaCYP707A1, and another one for the specific Na+/H+ plasma membrane antiporter FaSOS1 involve in osmotic homeostasis. FaSOS1, FaCYP707A1, and FabZIP69 were induced early at 6 h after NaCl treatment, while FaSOS1 and FaCYP707A1 were transcribed gradually after exposure to PEG. However, stress interactions showed a significantly increased expression in all genes. Expression of these genes was positively correlated to Pro, SSs, IL, DPPH, and antioxidant enzyme activity and negatively correlated with RWC, total Chl, and MSI. Chemical analyses showed that tall fescue plants exposed to the combination of stresses exhibited increased quantity of reactive oxygen species (H2O2), EL and DPPH, and higher levels of antioxidant enzyme activities (CAT, and SOD), Pro, and SSs content, compared with control seedlings. Under dual-stress conditions, the expression of FabZIP69 was effective in controlling the expression of FaSOS1 and FaADC1 genes differently.

PbGBF3 enhances salt response in pear by upregulating PbAPL2 and PbSDH1 and reducing ABA-mediated salt sensitivity

Pear is a widely cultivated fruit crop, but its distribution and sustainable production are significantly limited by salt stress. This study used RNA-Seq time-course analysis, WGCNA, and functional enrichment analysis to uncover the molecular mechanisms underlying salt stress tolerance in Pyrus ussuriensis. We identified an ABA-related regulatory module, PbGBF3-PbAPL2-PbSDH1, as crucial in this response. PbGBF3, a bZIP transcription factor, enhances salt tolerance by upregulating PbAPL2 and PbSDH1. Overexpression of PbGBF3 improved salt tolerance in Pyrus communis calli and Arabidopsis, while silencing it reduced tolerance in Pyrus betulifolia. Functional assays showed that PbGBF3 binds to the promoters of PbAPL2 and PbSDH1, increasing their expression. PbAPL2 and PbSDH1, key enzymes in starch synthesis and the sorbitol pathway, respectively, enhance salt tolerance by increasing AGPase activity, soluble sugar content, and SDH activity, improving ROS scavenging and ion balance. Our findings suggest that the PbGBF3-PbAPL2 and PbGBF3-PbSDH1 modules positively regulate salt tolerance by enhancing ABA signaling and reducing ABA-mediated growth inhibition. These insights provide a foundation for developing salt-tolerant pear cultivars.

Transcriptome dynamics in Artemisia annua provides new insights into cold adaptation and de-adaptation

Plants adapt to cold stress through a tightly regulated process involving metabolic reprogramming and tissue remodeling to enhance tolerance within a short timeframe. However, the precise differences and interconnections among various organs during cold adaptation remain poorly understood. This study employed dynamic transcriptomic and metabolite quantitative analyses to investigate cold adaptation and subsequent de-adaptation in Artemisia annua, a species known for its robust resistance to abiotic stress. Our findings revealed distinct expression patterns in most differentially expressed genes (DEGs) encoding transcription factors and components of the calcium signal transduction pathway within the two organs under cold stress. Notably, the long-distance transport of carbon sources from source organs (leaves) to sink organs (roots) experienced disruption followed by resumption, while nitrogen transport from roots to leaves, primarily in the form of amino acids, exhibited acceleration. These contrasting transport patterns likely contribute to the observed differences in cold response between the two organs. The transcriptomic analysis further indicated that leaves exhibited increased respiration, accumulated anti-stress compounds, and initiated the ICE-CBF-COR signaling pathway earlier than roots. Differential expression of genes associated with cell wall biosynthesis suggests that leaves may undergo cell wall thickening while roots may experience thinning. Moreover, a marked difference was observed in phenylalanine metabolism between the two organs, with leaves favoring lignin production and roots favoring flavonoid synthesis. Additionally, our findings suggest that the circadian rhythm is crucial in integrating temperature fluctuations with the plant's internal rhythms during cold stress and subsequent recovery. Collectively, these results shed light on the coordinated response of different plant organs during cold adaptation, highlighting the importance of inter-organ communication for successful stress tolerance.

Expression of Foxtail Millet bZIP Transcription Factor SibZIP67 Enhances Drought Tolerance in Arabidopsis

Foxtail millet is a drought-tolerant cereal and forage crop. The basic leucine zipper (bZIP) gene family plays important roles in regulating plant development and responding to stresses. However, the roles of bZIP genes in foxtail millet remain largely uninvestigated. In this study, 92 members of the bZIP transcription factors were identified in foxtail millet and clustered into ten clades. The expression levels of four SibZIP genes (SibZIP11, SibZIP12, SibZIP41, and SibZIP67) were significantly induced after PEG treatment, and SibZIP67 was chosen for further analysis. The studies showed that ectopic overexpression of SibZIP67 in Arabidopsis enhanced the plant drought tolerance. Detached leaves of SibZIP67 overexpressing plants had lower leaf water loss rates than those of wild-type plants. SibZIP67 overexpressing plants improved survival rates under drought conditions compared to wild-type plants. Additionally, overexpressing SibZIP67 in plants displayed reduced malondialdehyde (MDA) levels and enhanced activities of antioxidant enzymes, including catalase (CAT), superoxide dismutase (SOD), and peroxidase (POD) under drought stress. Furthermore, the drought-related genes, such as AtRD29A, AtRD22, AtNCED3, AtABF3, AtABI1, and AtABI5, were found to be regulated in SibZIP67 transgenic plants than in wild-type Arabidopsis under drought conditions. These data suggested that SibZIP67 conferred drought tolerance in transgenic Arabidopsis by regulating antioxidant enzyme activities and the expression of stress-related genes. The study reveals that SibZIP67 plays a beneficial role in drought response in plants, offering a valuable genetic resource for agricultural improvement in arid environments.

The impacts of pullulan soaking on radish seed germination and seedling growth under salt stress

Pullulan can not only provide a source of organic carbon but also has excellent properties. However, current research is mostly limited to the physical properties of the high-molecular-weight components of pullulan, and little is known about the application of its low-molecular-weight components. This study was designed to explore the impact of presoaking of radish seeds in a pullulan solution on seed germination and subsequent seedling growth under salt stress conditions. Pullulan soaking was found to enhance the germination rates of radish seeds subjected to salt stress, while also enhancing the aboveground growth of radish seedlings. Pullulan soaking resulted in increases in chlorophyll, soluble protein, and soluble sugar concentrations in the leaves of these seedlings, together with greater peroxidase activity and root activity as well as decreases in Na+ and malondialdehyde concentrations. This provides an important reference for the application of pullulan in plant protection.

Transcriptome analysis suggested that lncRNAs regulate rapeseed seedlings in responding to drought stress by coordinating the phytohormone signal transduction pathways

The growth, yield, and seed quality of rapeseed are negatively affected by drought stress. Therefore, it is of great value to understand the molecular mechanism behind this phenomenon. In a previous study, long non-coding RNAs (lncRNAs) were found to play a key role in the response of rapeseed seedlings to drought stress. However, many questions remained unanswered. This study was the first to investigate the expression profile of lncRNAs not only under control and drought treatment, but also under the rehydration treatment. A total of 381 differentially expressed lncRNA and 10,253 differentially expressed mRNAs were identified in the comparison between drought stress and control condition. In the transition from drought stress to rehydration, 477 differentially expressed lncRNAs and 12,543 differentially expressed mRNAs were detected. After identifying the differentially expressed (DE) lncRNAs, the comprehensive lncRNAs-engaged network with the co-expressed mRNAs in leaves under control, drought and rehydration was investigated. The Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analysis of co-expressed mRNAs identified the most significant pathways related with plant hormones (expecially abscisic acid, auxin, cytokinins, and gibberellins) in the signal transduction. The genes, co-expressed with the most-enriched DE-lncRNAs, were considered as the most effective candidates in the water-loss and water-recovery processes, including protein phosphatase 2 C (PP2C), ABRE-binding factors (ABFs), and SMALL AUXIN UP-REGULATED RNAs (SAURs). In summary, these analyses clearly demonstrated that DE-lncRNAs can act as a regulatory hub in plant-water interaction by controlling phytohormone signaling pathways and provided an alternative way to explore the complex mechanisms of drought tolerance in rapeseed.

Transcriptome Analysis of the Regulatory Mechanisms of Holly (Ilex dabieshanensis) under Salt Stress Conditions

The holly Ilex dabieshanensis K. Yao & M. B. Deng, a tree endemic to the Dabieshan Mountains region in China, is a commonly used landscaping plant. Like other crops, its growth is affected by salt stress. The molecular mechanism underlying salt tolerance in holly is still unclear. In this study, we used NaCl treatment and RNA sequencing (RNA-seq) at different times to identify the salt stress response genes of holly. A total of 4775 differentially expressed genes (DEGs) were identified. Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis of the DEGs obtained at different salt treatment times (3, 6, 9, 12, and 24 h), as compared to control (ck, 0 h), showed that plant hormone signal transduction and carotenoid biosynthesis were highly enriched. The mechanism by which holly responds to salt stress involves many plant hormones, among which the accumulation of abscisic acid (ABA) and its signal transduction may play an important role. In addition, ion homeostasis, osmotic metabolism, accumulation of antioxidant enzymes and nonenzymatic antioxidant compounds, and transcription factors jointly regulate the physiological balance in holly, providing important guarantees for its growth and development under conditions of salt stress. These results lay the foundation for studying the molecular mechanisms of salt tolerance in holly and for the selection of salt-tolerant varieties.

Transcriptomic Analysis Under Drought and Salt Stress Provides Insight into Genes Putatively Involved in Ginsenoside Biosynthesis in Panax japonicus Meyer

Panax japonicus Meyer, a perennial herb of the dicotyledonaceae family Araliaceae, is a rare folk traditional Chinese medicine, known as "the king of herbal medicine" in China. To understand the genes involved in secondary pathways under drought and salt stress, the transcriptomic analysis of P. japonicus is of vital importance. The transcriptome of underground rhizomes, stems, and leaves under drought and salt stress in P. japonicus were performed using the Illumina HiSeq platform. After de novo assembly of transcripts, expression profiling and identified differentially expressed genes (DEGs) were performed. Furthermore, putative functions of identified DEGs correlated with ginsenoside in P. japonicus were explored using Gene Ontology terms and Kyoto Encyclopedia of Genes and Genome (KEGG) pathway enrichment analysis. A total of 221,804 unigenes were obtained from the transcriptome of P. japonicus. The further analysis revealed that 10,839 unigenes were mapped to 91 KEGG pathways. Furthermore, a total of two metabolic pathways of P. japonicus in response to drought and salt stress related to triterpene saponin synthesis were screened. The sesquiterpene and triterpene metabolic pathways were annotated and finally putatively involved in ginsenoside content and correlation analysis of the expression of these genes were analyzed to identify four genes, β-amyrin synthase, isoprene synthase, squalene epoxidase, and 1-deoxy-D-ketose-5-phosphate synthase, respectively. Our results paves the way for screening highly expressed genes and mining genes related to triterpenoid saponin synthesis. It also provides valuable references for the study of genes involved in ginsenoside biosynthesis and signal pathway of P. japonicus.

Impact of Drought Stress on Plant Growth and Its Management Using Plant Growth Promoting Rhizobacteria

Drought stress is a significant environmental challenge affecting global agriculture, leading to substantial reductions in crop yields and overall plant productivity. It induces a cascade of physiological and biochemical changes in plants, including reduced water uptake, stomatal closure, and alterations in hormonal balance, all of which contribute to impaired growth and development. Drought stress diminishes crop production by impacting crucial plant metabolic pathways. Plants possess the ability to activate or deactivate specific sets of genes, leading to changes in their physiological and morphological characteristics. This adaptive response enables plants to evade, endure, or prevent the effects of drought stress. Drought stress triggers the activation of various genes, transcription factors, and signal transduction pathways in plants. In this context, imposing plant growth-promoting rhizobacteria (PGPR) emerges as a promising strategy. PGPR, employing diverse mechanisms such as osmotic adjustments, antioxidant activity, and phytohormone production, not only ensures the plant's survival during drought conditions but also enhances its overall growth. This comprehensive review delves into the various mechanisms through which PGPR enhances drought stress resistance, offering a thorough exploration of recent molecular and omics-based approaches to unravel the role of drought-responsive genes. The manuscript encompasses a detailed mechanistic analysis, along with the development of PGPR-based drought stress management in plants.

Isolation and functional characterization of cold-induced gene (AmCIP) promoter from Ammopiptanthus mongolicus

AmCIP is a dehydrin-like protein which involved in abiotic stress tolerance in xerophytes evergreen woody plant A. mongolicus. AmCIP could be induced in the cotyledon and radicle during cold acclimation. To further elucidate the regulation of the upstream region of the gene, we isolated and characterized the promoter of AmCIP. Herein, a 1115 bp 5'-flanking region of AmCIP genomic DNA was isolated and cloned by genome walking from A. mongolicus and the segment sequence was identified as "PrAmCIP" promoter. Analysis of the promoter sequence revealed the presences of some basic cis-acting elements, which were related to various environmental stresses and plant hormones. GUS histochemical staining of transgene tobacco showed that PrAmCIP was induced by 4℃, 55℃, NaCl, mannitol and ABA, whereas it could hardly drive GUS gene expression under normal conditions. Furthermore, we constructed three deletion fragments and genetically transformed them into Arabidopsis thaliana. GUS histochemical staining showed that the MYCATERD1 element of the CP7 fragment (-189 ∼ -1) may be a key element in response to drought. In conclusion, we provide an inducible promoter, PrAmCIP, which can be applied to the development of transgenic plants for abiotic stresse tolerance.

Transcription factor ZmDof22 enhances drought tolerance by regulating stomatal movement and antioxidant enzymes activities in maize (Zea mays L.)

KEY MESSAGE

The Dof22 gene encoding a deoxyribonucleic acid binding with one finger in maize, which is associated with its drought tolerance. The identification of drought stress regulatory genes is essential for the genetic improvement of maize yield. Deoxyribonucleic acid binding with one finger (Dof), a plant-specific transcription factor family, is involved in signal transduction, morphogenesis, and environmental stress responses. In present study, by weighted correlation network analysis (WGCNA) and gene co-expression network analysis, 15 putative Dof genes were identified from maize that respond to drought and rewatering. A real-time fluorescence quantitative PCR showed that these 15 genes were strongly induced by drought and ABA treatment, and among them ZmDof22 was highly induced by drought and ABA treatment. Its expression level increased by nearly 200 times after drought stress and more than 50 times after ABA treatment. After the normal conditions were restored, the expression levels were nearly 100 times and 40 times of those before treatment, respectively. The Gal4-LexA/UAS system and transcriptional activation analysis indicate that ZmDof22 is a transcriptional activator regulating drought tolerance and recovery ability in maize. Further, overexpressed transgenic and mutant plants of ZmDof22 by CRISPR/Cas9, indicates that the ZmDof22, improves maize drought tolerance by promoting stomatal closure, reduces water loss, and enhances antioxidant enzyme activity by participating in the ABA pathways. Taken together, our findings laid a foundation for further functional studies of the ZmDof gene family and provided insights into the role of the ZmDof22 regulatory network in controlling drought tolerance and recovery ability of maize.

Factors affecting the production of sugarcane yield and sucrose accumulation: suggested potential biological solutions

Environmental stresses are the main constraints on agricultural productivity and food security worldwide. This issue is worsened by abrupt and severe changes in global climate. The formation of sugarcane yield and the accumulation of sucrose are significantly influenced by biotic and abiotic stresses. Understanding the biochemical, physiological, and environmental phenomena associated with these stresses is essential to increase crop production. This review explores the effect of environmental factors on sucrose content and sugarcane yield and highlights the negative effects of insufficient water supply, temperature fluctuations, insect pests, and diseases. This article also explains the mechanism of reactive oxygen species (ROS), the role of different metabolites under environmental stresses, and highlights the function of environmental stress-related resistance genes in sugarcane. This review further discusses sugarcane crop improvement approaches, with a focus on endophytic mechanism and consortium endophyte application in sugarcane plants. Endophytes are vital in plant defense; they produce bioactive molecules that act as biocontrol agents to enhance plant immune systems and modify environmental responses through interaction with plants. This review provides an overview of internal mechanisms to enhance sugarcane plant growth and environmental resistance and offers new ideas for improving sugarcane plant fitness and crop productivity.

Transcriptional dynamics reveals the asymmetrical events underlying graft union formation in pecan (Carya illinoinensis)

Grafting is a widely used technique for pecan propagation; however, the background molecular events underlying grafting are still poorly understood. In our study, the graft partners during pecan [Carya illinoinensis (Wangenh.) K. Koch] graft union formation were separately sampled for RNA-seq, and the transcriptional dynamics were described via weighted gene co-expression network analysis. To reveal the main events underlying grafting, the correlations between modules and grafting traits were analyzed. Functional annotation showed that during the entire graft process, signal transduction was activated in the scion, while messenger RNA splicing was induced in the rootstock. At 2 days after grafting, the main processes occurring in the scion were associated with protein synthesis and processing, while the primary processes occurring in the rootstock were energy release-related. During the period of 7-14 days after grafting, defense response was a critical process taking place in the scion; however, the main process functioning in the rootstock was photosynthesis. From 22 to 32 days after grafting, the principal processes taking place in the scion were jasmonic acid biosynthesis and defense response, whereas the highly activated processes associated with the rootstock were auxin biosynthesis and plant-type secondary cell wall biogenesis. To further prove that the graft partners responded asymmetrically to stress, hydrogen peroxide contents as well as peroxidase and β-1,3-glucanase activities were detected, and the results showed that their levels were increased in the scion not the rootstock at certain time points after grafting. Our study reveals that the scion and rootstock might respond asymmetrically to grafting in pecan, and the scion was likely associated with stress response, while the rootstock was probably involved in energy supply and xylem bridge differentiation during graft union formation.

The AP2/ERF transcription factor MdDREB2A regulates nitrogen utilisation and sucrose transport under drought stress

Drought stress is one of the main environmental factors limiting plant growth and development. Plants adapt to changing soil moisture by modifying root architecture, inducing stomatal closure, and inhibiting shoot growth. The AP2/ERF transcription factor DREB2A plays a key role in maintaining plant growth in response to drought stress, but the molecular mechanism underlying this process remains to be elucidated. Here, it was found that overexpression of MdDREB2A positively regulated nitrogen utilisation by interacting with DRE cis-elements of the MdNIR1 promoter. Meanwhile, MdDREB2A could also directly bind to the promoter of MdSWEET12, which may enhance root development and nitrogen assimilation, ultimately promoting plant growth. Overall, this regulatory mechanism provides an idea for plants in coordinating with drought tolerance and nitrogen assimilation to maintain optimal plant growth and development under drought stress.

From swamp to field: how genes from mangroves and its associates can enhance crop salinity tolerance

Salinity stress is a critical challenge in crop production and requires innovative strategies to enhance the salt tolerance of plants. Insights from mangrove species, which are renowned for their adaptability to high-salinity environments, provides valuable genetic targets and resources for improving crops. A significant hurdle in salinity stress is the excessive uptake of sodium ions (Na+) by plant roots, causing disruptions in cellular balance, nutrient deficiencies, and hampered growth. Specific ion transporters and channels play crucial roles in maintaining a low Na+/K+ ratio in root cells which is pivotal for salt tolerance. The family of high-affinity potassium transporters, recently characterized in Avicennia officinalis, contributes to K+ homeostasis in transgenic Arabidopsis plants even under high-salt conditions. The salt overly sensitive pathway and genes related to vacuolar-type H+-ATPases hold promise for expelling cytosolic Na+ and sequestering Na+ in transgenic plants, respectively. Aquaporins contribute to mangroves' adaptation to saline environments by regulating water uptake, transpiration, and osmotic balance. Antioxidant enzymes mitigate oxidative damage, whereas genes regulating osmolytes, such as glycine betaine and proline, provide osmoprotection. Mangroves exhibit increased expression of stress-responsive transcription factors such as MYB, NAC, and CBFs under high salinity. Moreover, genes involved in various metabolic pathways, including jasmonate synthesis, triterpenoid production, and protein stability under salt stress, have been identified. This review highlights the potential of mangrove genes to enhance salt tolerance of crops. Further research is imperative to fully comprehend and apply these genes to crop breeding to improve salinity resilience.

Applications of humic and fulvic acid under saline soil conditions to improve growth and yield in barley

BACKGROUND

Enriching the soil with organic matter such as humic and fulvic acid to increase its content available nutrients, improves the chemical properties of the soil and increases plant growth as well as grain yield. In this study, we conducted a field experiment using humic acid (HA), fulvic acid (FA) and recommended dose (RDP) of phosphorus fertilizer to treat Hordeum vulgare seedling, in which four concentrations from HA, FA and RDP (0.0 %, 50 %, 75 % and 100%) under saline soil conditions . Moreover, some agronomic traits (e.g. grain yield, straw yield, spikes weight, plant height, spike length and spike weight) in barley seedling after treated with different concentrations from HA, FA and RDP were determined. As such the beneficial effects of these combinations to improve plant growth, N, P, and K uptake, grain yield, and its components under salinity stress were assessed.

RESULTS

The findings showed that the treatments HA + 100% RDP (T1), HA + 75% RDP (T2), FA + 100% RDP (T5), HA + 50% RDP (T3), and FA + 75% RDP (T6), improved number of spikes/plant, 1000-grain weight, grain yield/ha, harvest index, the amount of uptake of nitrogen (N), phosphorous (P) and potassium (K) in straw and grain. The increase for grain yield over the control was 64.69, 56.77, 49.83, 49.17, and 44.22% in the first season, and 64.08, 56.63, 49.19, 48.87, and 43.69% in the second season,. Meanwhile, the increase for grain yield when compared to the recommended dose was 22.30, 16.42, 11.27, 10.78, and 7.11% in the first season, and 22.17, 16.63, 11.08, 10.84, and 6.99% in the second season. Therefore, under salinity conditions the best results were obtained when, in addition to phosphate fertilizer, the soil was treated with humic acid or foliar application the plants with fulvic acid under one of the following treatments: HA + 100% RDP (T1), HA + 75% RDP (T2), FA + 100% RDP (T5), HA + 50% RDP (T3), and FA + 75% RDP (T6).

CONCLUSIONS

The result of the use of organic amendments was an increase in the tolerance of barley plant to salinity stress, which was evident from the improvement in the different traits that occurred after the treatment using treatments that included organic amendments (humic acid or fulvic acid).

An eco-friendly versatile superabsorbent hydrogel based on sodium alginate and urea for soil improvement with a synchronous chemical loading strategy

In this paper, an eco-friendly versatile superabsorbent material was designed for soil improvement, and a synchronous chemical loading strategy was proposed. In this strategy, urea not only acted as fertilizer but also acted as a crosslinker to construct an alginate network. The microstructure, chemical structure, thermal stability and composition of the obtained SA/urea hydrogel were characterized in detail. Adsorption behavior and application performance in agriculture were evaluated. The results demonstrated that urea had two different conformations in the network. The SA/urea hydrogel had abundant pore structures with excellent water absorption performance. It could not only improve the water retention capacity of soil but also release nitrogen, phosphorus and potassium elements with degradation for as long as 9 weeks. Moreover, the hydrogel could promote plant growth, increase the nutritional composition of plants and inhibit the accumulation of harmful nitrate in plants. With advantages, including biodegradability, high water absorption, controllable degradation, excellent water retention, sustained NPK release and improved plant nutrition value, the SA/urea hydrogel has great potential for soil improvement in agriculture as an eco-friendly versatile water retention agent and can be expected to extend to more fields as a novel superabsorbent material.

A genome-wide association analysis for salt tolerance during the soybean germination stage and development of KASP markers

Salt stress poses a significant challenge to crop productivity, and understanding the genetic basis of salt tolerance is paramount for breeding resilient soybean varieties. In this study, a soybean natural population was evaluated for salt tolerance during the germination stage, focusing on key germination traits, including germination rate (GR), germination energy (GE), and germination index (GI). It was seen that under salt stress, obvious inhibitions were found on these traits, with GR, GE, and GI diminishing by 32% to 54% when compared to normal conditions. These traits displayed a coefficient of variation (31.81% to 50.6%) and a substantial generalized heritability (63.87% to 86.48%). Through GWAS, a total of 1841 significant single-nucleotide polymorphisms (SNPs) were identified to be associated with these traits, distributed across chromosome 2, 5, 6, and 20. Leveraging these significant association loci, 12 candidate genes were identified to be associated with essential functions in coordinating cellular responses, regulating osmotic stress, mitigating oxidative stress, clearing reactive oxygen species (ROS), and facilitating heavy metal ion transport - all of which are pivotal for plant development and stress tolerance. To validate the candidate genes, quantitative real-time polymerase chain reaction (qRT-PCR) analysis was conducted, revealing three highly expressed genes (Glyma.02G067700, Glyma.02G068900, and Glyma.02G070000) that play pivotal roles in plant growth, development, and osmoregulation. In addition, based on these SNPs related with salt tolerance, KASP (Kompetitive Allele-Specific PCR)markers were successfully designed to genotype soybean accessions. These findings provide insight into the genetic base of soybean salt tolerance and candidate genes for enhancing soybean breeding programs in this study.

Understanding the mechanistic basis of plant adaptation to salinity and drought

Plant growth and development is adversely affected by environmental constraints, particularly salinity and drought. Climate change has escalated the effect of salinity and drought on crops in varying ways, affecting agriculture and most importantly crop productivity. These stressors influence plants across a wide range of levels, including their morphology and physiological, biochemical, and molecular processes. Plant responses to salinity and drought stress have been the subject of intense research being explored globally. Considering the importance of the impact that these stresses can have on agriculture in the short term, novel strategies are being sought and adopted in breeding programs. Better understanding of the molecular, biochemical, and physiological responses of agriculturally important plants will ultimately help promote global food security. Moreover, considering the present challenges for agriculture, it is critical to consider how we can effectively transfer the knowledge generated with these approaches in the laboratory to the field, so as to mitigate these adversities. The present collection discusses how drought and salinity exert effects on plants.

Differential protein analysis of saline-alkali promoting the oil accumulation in Nitzschia palea

BACKGROUND

The increasingly severe salinization of the aquatic environment has led to serious damage to the habitats of aquatic organisms. Benthic diatoms are commonly employed as indicator species for assessing water quality and serve as a reflection of the overall health of the aquatic ecosystem. Nitzschia palea is a common diatom found in freshwater, with high oil content, rapid reproductive rate, and it is a commonly dominant species in various rivers.

RESULTS

The results showed that after 4 days (d) of saline-alkali stress, the cell density and chlorophyll a content of Nitzschia palea reached their maximum values. Therefore, we selected Nitzschia palea under 4 d stress for Tandem Mass Tag (TMT) quantitative proteomic analysis to explore the molecular adaptation mechanism of freshwater diatoms under saline-alkali stress. Totally, 854 proteins were enriched, of which 439 differentially expressed proteins were identified. Gene ontology (GO), Kyoto Encyclopedia of Genes and Genomes (KEGG), and subcellular fractionation analysis revealed that these proteins were mainly enriched in the photosynthesis pathway, citric acid cycle (TCA cycle), fatty acid synthesis, and glutathione cycle.

CONCLUSIONS

This study aims to reveal the physiological, biochemical and proteomic mechanisms of salt and alkali tolerance and molecular adaptation of Nitzschia palea under different saline-alkali concentrations. This study showed that Nitzschia palea is one candidate of the environmental friendly, renewable bioenergy microalgae. Meantime, Nitzschia palea reveals for the proteome of the freshwater and provides the basis, it became a model algal species for freshwater diatoms.

Genome-wide analysis of the Tritipyrum NAC gene family and the response of TtNAC477 in salt tolerance

NAC transcription factors are widely distributed in the plant kingdom and play an important role in the response to various abiotic stresses in plant species. Tritipyrum, an octoploid derived from hybridization of Triticum aestivum (AABBDD) and Thinopyrum elongatum (EE), is an important genetic resource for integrating the desirable traits of Th. elongatum into wheat. In this study, we investigated the tissue distribution and expression of Tritipyrum NAC genes in the whole genomes of T. aestivum and Th. elongatum after obtaining their complete genome sequences. Based on phylogenetic relationships, conserved motifs, gene synthesis, evolutionary analysis, and expression patterns, we identified and characterized 732 Tritipyrum NAC genes. These genes were divided into six main groups (A, B, C, D, E, and G) based on phylogenetic relationships and evolutionary studies, with members of these groups sharing the same motif composition. The 732 TtNAC genes are widely distributed across 28 chromosomes and include 110 duplicated genes. Gene synthesis analysis indicated that the NAC gene family may have a common ancestor. Transcriptome data and quantitative polymerase chain reaction (qPCR) expression profiles showed 68 TtNAC genes to be highly expressed in response to various salt stress and recovery treatments. Tel3E01T644900 (TtNAC477) was particularly sensitive to salt stress and belongs to the same clade as the salt tolerance genes ANAC019 and ANAC055 in Arabidopsis. Pearson correlation analysis identified 751 genes that correlated positively with expression of TtNAC477, and these genes are enriched in metabolic activities, cellular processes, stimulus responses, and biological regulation. TtNAC477 was found to be highly expressed in roots, stems, and leaves in response to salt stress, as confirmed by real-time PCR. These findings suggest that TtNAC477 is associated with salt tolerance in plants and might serve as a valuable exogenous gene for enhancing salt tolerance in wheat.

Modulation of antioxidant defense and PSII components by exogenously applied acetate mitigates salinity stress in Avena sativa

Salinity stress has detrimental effects on various aspects of plant development. However, our understanding of strategies to mitigate these effects in crop plants remains limited. Recent research has shed light on the potential of sodium acetate as a mitigating component against salinity stress in several plant species. Here, we show the role of acetate sodium in counteracting the adverse effects on oat (Avena sativa) plants subjected to NaCl-induced salinity stress, including its impact on plant morphology, photosynthetic parameters, and gene expression related to photosynthesis and antioxidant capacity, ultimately leading to osmoprotection. The five-week experiment involved subjecting oat plants to four different conditions: water, salt (NaCl), sodium acetate, and a combination of salt and sodium acetate. The presence of NaCl significantly inhibited plant growth and root elongation, disrupted chlorophylls and carotenoids content, impaired chlorophyll fluorescence, and down-regulated genes associated with the plant antioxidant defense system. Furthermore, our findings reveal that when stressed plants were treated with sodium acetate, it partially reversed these adverse effects across all analyzed parameters. This reversal was particularly evident in the increased content of proline, thereby ensuring osmoprotection for oat plants, even under stressful conditions. These results provide compelling evidence regarding the positive impact of sodium acetate on various plant development parameters, with a particular focus on the enhancement of photosynthetic activity.

Genome-Wide Identification and Expression Analysis of Calmodulin and Calmodulin-like Genes, Revealing CaM3 and CML13 Participating in Drought Stress in Phoebe bournei

Calmodulin (CaM) and calmodulin-like (CML) proteins are major Ca2+ sensors involved in the regulation of plant development and stress responses by converting Ca2+ signals into appropriate cellular responses. However, characterization and expression analyses of CaM/CML genes in the precious species, Phoebe bournei, remain limited. In this study, five PbCaM and sixty PbCML genes were identified that only had EF-hand motifs with no other functional domains. The phylogenetic tree was clustered into 11 subgroups, including a unique clade of PbCaMs. The PbCaMs were intron-rich with four EF-hand motifs, whereas PbCMLs had two to four EF-hands and were mostly intronless. PbCaMs/CMLs were unevenly distributed across the 12 chromosomes of P. bournei and underwent purifying selection. Fragment duplication was the main driving force for the evolution of the PbCaM/CML gene family. Cis-acting element analysis indicated that PbCaMs/CMLs might be related to hormones, growth and development, and stress response. Expression analysis showed that PbCaMs were generally highly expressed in five different tissues and under drought stress, whereas PbCMLs showed specific expression patterns. The expression levels of 11 candidate PbCaMs/CMLs were responsive to ABA and MeJA, suggesting that these genes might act through multiple signaling pathways. The overexpression of PbCaM3/CML13 genes significantly increased the tolerance of yeast cells to drought stress. The identification and characterization of the CaM/CML gene family in P. bournei laid the foundation for future functional studies of these genes.

Wheat WRKY transcription factor TaWRKY24 confers drought and salt tolerance in transgenic plants

Drought and salt stress are major environmental conditions that severely limit plant growth and productivity. WRKY transcription factors play a vital role in the responses against biotic or abiotic stress. In this study, TaWRKY24, a gene of the IIe WRKY family identified in wheat, was cloned and characterized. TaWRKY24 was mainly expressed in wheat leaf and stem and induced by treatment with PEG6000, salt, H2O2, ABA, MeJA, and ethrel. TaWRKY24 transient expression in onion epidermal cells suggested its nuclear localization and its transcriptional activation capability characteristics. Overexpression of TaWRKY24 in tobacco improved the seed germination rate and root growth of seedlings in transgenic lines when subjected to higher mannitol and NaCl concentrations. Further research showed that transgenic lines had higher proline and soluble sugars and lower levels of reactive oxygen species (ROS) and malondialdehyde (MDA). Moreover, compared to normal and negative control plants, TaWRKY24 silenced wheat seedlings had reduced growth under salt and drought stress. This study shows that wheat TaWRKY24 is crucial to plant stress, providing an excellent candidate gene for wheat resistance breeding.

Co-Expression Network Analysis of the Transcriptome Identified Hub Genes and Pathways Responding to Saline-Alkaline Stress in Sorghum bicolor L

Soil salinization, an intractable problem, is becoming increasingly serious and threatening fragile natural ecosystems and even the security of human food supplies. Sorghum (Sorghum bicolor L.) is one of the main crops growing in salinized soil. However, the tolerance mechanisms of sorghum to saline-alkaline soil are still ambiguous. In this study, RNA sequencing was carried out to explore the gene expression profiles of sorghum treated with sodium bicarbonate (150 mM, pH = 8.0, treated for 0, 6, 12 and 24 h). The results show that 6045, 5122, 6804, 7978, 8080 and 12,899 differentially expressed genes (DEGs) were detected in shoots and roots after 6, 12 and 24 h treatments, respectively. GO, KEGG and weighted gene co-expression analyses indicate that the DEGs generated by saline-alkaline stress were primarily enriched in plant hormone signal transduction, the MAPK signaling pathway, starch and sucrose metabolism, glutathione metabolism and phenylpropanoid biosynthesis. Key pathway and hub genes (TPP1, WRKY61, YSL1 and NHX7) are mainly related to intracellular ion transport and lignin synthesis. The molecular and physiological regulation processes of saline-alkali-tolerant sorghum are shown by these results, which also provide useful knowledge for improving sorghum yield and quality under saline-alkaline conditions.

The rice annexin gene OsAnn5 is involved in cold stress tolerance at the seedling stage

Annexins exist widely in plants as multigene families and play critical roles in stress responses and a range of cellular processes. This study provides a comprehensive account of the cloning and functional characterization of the rice annexin gene OsAnn5. The findings reveal that a cold stress treatment at the seedling stage of rice induced OsAnn5 expression. GUS staining assay indicated that the expression of OsAnn5 was non tissue-specific and was detected in almost all rice tissues. Subcellular localization indicated that OsAnn5-GFP (green fluorescent protein) signals were found in the endoplasmic reticulum apparatus. Compared with wild type rice, knocking out OsAnn5 using the CRISPR/Cas9 (clustered regularly interspaced short palindromic repeats/CRISPR associated proteins) mediated genome editing resulted in sensitivity to cold treatments. These results indicate that OsAnn5 is involved in cold stress tolerance at the seedling stage.

Silencing the CsSnRK2.11 Gene Decreases Drought Tolerance of Cucumis sativus L

Drought stress restricts vegetable growth, and abscisic acid plays an important role in its regulation. Sucrose non-fermenting1-related protein kinase 2 (SnRK2) is a key enzyme in regulating ABA signal transduction in plants, and it plays a significant role in response to multiple abiotic stresses. Our previous experiments demonstrated that the SnRK2.11 gene exhibits a significant response to drought stress in cucumbers. To further investigate the function of SnRK2.11 under drought stress, we used VIGS (virus-induced gene silencing) technology to silence this gene and conducted RNA-seq analysis. The SnRK2.11-silencing plants displayed increased sensitivity to drought stress, which led to stunted growth and increased wilting speed. Moreover, various physiological parameters related to photosynthesis, chlorophyll fluorescence, leaf water content, chlorophyll content, and antioxidant enzyme activity were significantly reduced. The intercellular CO2 concentration, non-photochemical burst coefficient, and malondialdehyde and proline content were significantly increased. RNA-seq analysis identified 534 differentially expressed genes (DEGs): 311 were upregulated and 223 were downregulated. GO functional annotation analysis indicated that these DEGs were significantly enriched for molecular functions related to host cells, enzyme activity, and stress responses. KEGG pathway enrichment analysis further revealed that these DEGs were significantly enriched in phytohormone signalling, MAPK signalling, and carotenoid biosynthesis pathways, all of which were associated with abscisic acid. This study used VIGS technology and transcriptome data to investigate the role of CsSnRK2.11 under drought stress, offering valuable insights into the mechanism of the SnRK2 gene in enhancing drought resistance in cucumbers.