Lignin deposition in chickpea root xylem under drought

MicroRNA408 negatively regulates drought tolerance by controlling lignin synthesis in potato

Potato is an important food crop in China, and its growth and development are vulnerable to abiotic stresses. The effect of drought on potato growth and development is more dramatic. In this study, StLAC12 was verified as target gene of potato Stu-miR408. It was demonstrated that Stu-miR408 negatively regulated expression of StLAC12. The effect of Stu-miR408 on plant drought resistance was also investigated, and it was found that down-regulated expression of Stu-miR408 can enhance drought resistance of potato. It was also found that lignin synthesis was affected by Stu-miR408, and miR408-LAC12 can affect xylem development by regulating lignin synthesis in response to drought stress. In conclusion, this study demonstrated that Stu-miR408 negatively regulates potato drought tolerance and provided valuable new insights into Stu-miR408-mediated lignin synthesis pathway in response to potato drought stress.

The analysis of the genetic loci affecting phenotypic plasticity of soybean isoflavone content by dQTG.seq model

KEY MESSAGE

The dQTG.seq model was utilized to investigate the genetic underpinnings of phenotypic plasticity in soybean isoflavone content, leading to the identification of 100 marker sites associated with phenotypic plasticity, including 27 transcription factors. Overexpression of Glyma.18G091600 (GmERF7) hairy roots under low temperature, salt, and drought stress confirmed the regulatory role of GmERF7 in the phenotypic plasticity of soybean isoflavone content. Phenotypic plasticity is characteristic of organisms that undergo phenotypic changes in response to environmental fluctuations. This phenomenon is pivotal in evolutionary processes and the emergence of new traits. Isoflavones, significant secondary metabolites found in soybeans, have garnered considerable attention owing to their beneficial physiological effects on human health. The variation in isoflavone content among different soybean varieties is influenced by diverse environmental factors, thereby influencing the evaluation of high and low isoflavone varieties. In this study, we measured the phenotypic plasticity of isoflavone content in recombinant inbred lines Hefeng 25 and L-28 in three different environments over two years. Utilizing the dQTG.seq model, 100 statistically significant markers were identified, and 101 potential genes, including 27 transcription factors, were screened. Through qRT-PCR analysis, elevated expression levels of Glyma.18G091600, Glyma.09G196200, and Glyma.05G229500 were observed in various parts of soybean plants. Under low temperature, drought or salt stress conditions, the related enzymes involved in the isoflavone synthesis pathway were notably upregulated in Glyma.18G091600 (GmERF7) overexpressed hairy roots compared to wild-type controls, resulting to higher phenotypic plasticity values for DZ, GC, GT, and TI. These results suggest that GmERF7 influences the phenotypic plasticity of soybean isoflavone content, enhancing adaptation to adverse environments, while also promoting the synthesis and accumulation of soybean isoflavones.

CsLAC4, regulated by CsmiR397a, confers drought tolerance to the tea plant by enhancing lignin biosynthesis

Drought is a prevalent abiotic stress that commonly affects the quality and yield of tea. Although numerous studies have shown that lignin accumulation holds significant importance in conferring drought tolerance to tea plants, the underlying molecular regulatory mechanisms governing the tea plant's response to drought remain largely elusive. LACCASEs (LACs), which belong to the class of plant copper-containing polyphenol oxidases, have been widely reported to participate in lignin biosynthesis in plants and are implicated in numerous plant life processes, especially in the context of adverse conditions. In this study, we detected the upregulation of CsLAC4 in response to drought induction. Remarkably, the overexpression of CsLAC4 not only substantially increased the lignin content of transgenic Arabidopsis thaliana but also simulated the development of vascular tissues, consequently leading to a significant enhancement in drought tolerance. Moreover, via dual-luciferase assays and transient overexpression in tea leaves, we revealed that CsLAC4 was negatively regulated by the upstream CsmiR397a. Interestingly, the expression of CsmiR397a was downregulated during drought stress in tea plants. Arabidopsis thaliana overexpressing CsmiR397a showed increased sensitivity to drought stress. By transient overexpression of CsmiR397a and CsLAC4 in tea plant leaves, we verified that CsLAC4, which is regulated by CsmiR397a, conferred drought tolerance to tea plants by enhancing lignin biosynthesis. These findings enhance our understanding of the molecular regulatory mechanisms underlying the response of tea plants to drought stress.

Effects of water stress on apoplastic barrier formation in soil grown roots differ from hydroponically grown roots: Histochemical, biochemical and molecular evidence

In root research, hydroponic plant cultivation is commonly used and soil experiments are rare. We investigated the response of 12-day-old barley roots, cultivated in soil-filled rhizotrons, to different soil water potentials (SWP) comparing a modern cultivar (cv. Scarlett) with a wild accession ICB181243 from Pakistan. Water potentials were quantified in soils with different relative water contents. Root anatomy was studied using histochemistry and microscopy. Suberin and lignin amounts were quantified by analytical chemistry. Transcriptomic changes were observed by RNA-sequencing. Compared with control with decreasing SWP, total root length decreased, the onset of endodermal suberization occurred much closer towards the root tips, amounts of suberin and lignin increased, and corresponding biosynthesis genes were upregulated in response to decreasing SWP. We conclude that decreasing water potentials enhanced root suberization and lignification, like osmotic stress experiments in hydroponic cultivation. However, in soil endodermal cell suberization was initiated very close towards the root tip, and root length as well as suberin amounts were about twofold higher compared with hydroponic cultivation.

Overexpression of FERONIA receptor kinase MdMRLK2 regulates lignin accumulation and enhances water use efficiency in apple under long-term water deficit condition

Water use efficiency (WUE) is crucial for apple tree fitness and survival, especially in response to climatic changes. The receptor-like kinase FERONIA is reportedly an essential regulator of plant stress responses, but its role in regulating WUE under water deficit conditions is unclear. Here, we found that overexpressing the apple FERONIA receptor kinase gene, MdMRLK2, enhanced apple WUE under long-term water deficit conditions. Under drought treatment, 35S::MdMRLK2 apple plants exhibited higher photosynthetic capacity and antioxidant enzyme activities than wild-type (WT) plants. 35S::MdMRLK2 apple plants also showed increased biomass accumulation, root activity, and water potential compared to WT plants. Moreover, MdMRLK2 physically interacts with and phosphorylates cinnamoyl-CoA reductase 1, MdCCR1, an enzyme essential for lignin synthesis, at position Ser260. This interaction likely contributed to increased vessel density, vascular cylinder area, and lignin content in 35S::MdMRLK2 apple plants under drought conditions. Therefore, our findings reveal a novel function of MdMRLK2 in regulating apple WUE under water deficit conditions.

miR397 regulates cadmium stress response by coordinating lignin polymerization in the root exodermis in Kandelia obovata

Secondary lignification of the root exodermis of Kandelia obovata is crucial for its response to adversity such as high salinity and anaerobic environment, and this lignification is also effective in blocking cadmium transport to the roots. However, how the differences in lignification of root exodermis at different developmental stages respond to Cd stress and its regulatory mechanisms have not been revealed. In this study, after analyzing the root structure and cell wall thickness using a Phenom scanning electron microscope as well as measuring cadmium content in the root cell wall, we found that the exodermis of young and mature roots of K. obovata responded to Cd stress through the polymerization of different lignin monomers, forming two different mechanisms: chelation and blocking. Through small RNA sequencing, RLM-5'-RACE and dual luciferase transient expression system, we found that miR397 targets and regulates KoLAC4/17/7 expression. The expression of KoLAC4/17 promoted the accumulation of guaiacyl lignin during lignification and enhanced the binding of cadmium to the cell wall. Meanwhile, KoLAC7 expression promotes the accumulation of syringyl lignin during lignification, which enhances the obstruction of cadmium and improves the tolerance to cadmium. These findings enhance our understanding of the molecular mechanisms underlying the differential lignification of the root exodermis of K. obovata in response to cadmium stress, and provide scientific guidance for the conservation of mangrove forests under heavy metal pollution.

Methylation of microRNA genes and its effect on secondary xylem development of stem in poplar

MicroRNAs (miRNAs) and DNA methylation are both vital regulators of gene expression. DNA methylation can affect the transcription of miRNAs, just like coding genes, through methylating the CpG islands in the gene regions of miRNAs. Although previous studies have shown that DNA methylation and miRNAs can each be involved in the process of wood formation, the relationship between the two has been relatively little studied in plant wood formation. Studies have shown that the second internode (IN2) (from top to bottom) of 3-month-old poplar trees can represent the primary stage of poplar stem development and IN8 can represent the secondary stage. There were also significant differences in DNA methylation patterns and miRNA expression patterns obtained from PS and SS. In this study, we first interactively analyzed methylation and miRNA sequencing data to identify 43 differentially expressed miRNAs regulated by differential methylation from the primary stage and secondary stage, which were found to be involved in multiple biological processes related to wood formation by enrichment analysis. In addition, six miRNA/target gene modules were finally identified as potentially involved in secondary xylem development of poplar stems through degradome sequencing and functional analysis. In conclusion, this study provides important reference information on the mechanism of interaction between different regulatory pathways of wood formation.

Understanding role of roots in plant response to drought: Way forward to climate-resilient crops

Drought stress leads to a significant amount of agricultural crop loss. Thus, with changing climatic conditions, it is important to develop resilience measures in agricultural systems against drought stress. Roots play a crucial role in regulating plant development under drought stress. In this review, we have summarized the studies on the role of roots and root-mediated plant responses. We have also discussed the importance of root system architecture (RSA) and the various structural and anatomical changes that it undergoes to increase survival and productivity under drought. Various genes, transcription factors, and quantitative trait loci involved in regulating root growth and development are also discussed. A summarization of various instruments and software that can be used for high-throughput phenotyping in the field is also provided in this review. More comprehensive studies are required to help build a detailed understanding of RSA and associated traits for breeding drought-resilient cultivars.

Integrated physiological, metabolomic, and transcriptomic analyses elucidate the regulation mechanisms of lignin synthesis under osmotic stress in alfalfa leaf (Medicago sativa L.)

Alfalfa, an essential forage crop known for its high yield, nutritional value, and strong adaptability, has been widely cultivated worldwide. The yield and quality of alfalfa are frequently jeopardized due to environmental degradation. Lignin, a constituent of the cell wall, enhances plant resistance to abiotic stress, which often causes osmotic stress in plant cells. However, how lignin responds to osmotic stress in leaves remains unclear. This study explored the effects of osmotic stress on lignin accumulation and the contents of intermediate metabolites involved in lignin synthesis in alfalfa leaves. Osmotic stress caused an increase in lignin accumulation and the alteration of core enzyme activities and gene expression in the phenylpropanoid pathway. We identified five hub genes (CSE, CCR, CADa, CADb, and POD) and thirty edge genes (including WRKYs, MYBs, and UBPs) by integrating transcriptome and metabolome analyses. In addition, ABA and ethylene signaling induced by osmotic stress regulated lignin biosynthesis in a contradictory way. These findings contribute to a new theoretical foundation for the breeding of high-quality and resistant alfalfa varieties.

Proteomic analysis of leaves and roots during drought stress and recovery in Setaria italica L

Drought is a major environmental factor that limits agricultural crop productivity and threatens food security. Foxtail millet is a model crop with excellent abiotic stress tolerance and is consequently an important subject for obtaining a better understanding of the molecular mechanisms underlying plant responses to drought and recovery. Here the physiological and proteomic responses of foxtail millet (cultivar Yugu1) leaves and roots to drought treatments and recovery were evaluated. Drought-treated foxtail millet exhibited increased relative electrolyte leakage and decreased relative water content and chlorophyll content compared to control and rewatering plants. A global analysis of protein profiles was evaluated for drought-treated and recovery treatment leaves and roots. We also identified differentially abundant proteins in drought and recovery groups, enabling comparisons between leaf and root tissue responses to the conditions. The principal component analysis suggested a clear distinction between leaf and root proteomes for the drought-treated and recovery treatment plants. Gene Ontology enrichment and co-expression analyses indicated that the biological responses of leaves differed from those in roots after drought and drought recovery. These results provide new insights and data resources to investigate the molecular basis of tissue-specific functional responses of foxtail millet during drought and recovery, thereby significantly informing crop breeding.

Tomato deploys defence and growth simultaneously to resist bacterial wilt disease

Plant disease limits crop production, and host genetic resistance is a major means of control. Plant pathogenic Ralstonia causes bacterial wilt disease and is best controlled with resistant varieties. Tomato wilt resistance is multigenic, yet the mechanisms of resistance remain largely unknown. We combined metaRNAseq analysis and functional experiments to identify core Ralstonia-responsive genes and the corresponding biological mechanisms in wilt-resistant and wilt-susceptible tomatoes. While trade-offs between growth and defence are common in plants, wilt-resistant plants activated both defence responses and growth processes. Measurements of innate immunity and growth, including reactive oxygen species production and root system growth, respectively, validated that resistant plants executed defence-related processes at the same time they increased root growth. In contrast, in wilt-susceptible plants roots senesced and root surface area declined following Ralstonia inoculation. Wilt-resistant plants repressed genes predicted to negatively regulate water stress tolerance, while susceptible plants repressed genes predicted to promote water stress tolerance. Our results suggest that wilt-resistant plants can simultaneously promote growth and defence by investing in resources that act in both processes. Infected susceptible plants activate defences, but fail to grow and so succumb to Ralstonia, likely because they cannot tolerate the water stress induced by vascular wilt.

The miRNA-mRNA Regulatory Modules of Pinus massoniana Lamb. in Response to Drought Stress

Masson pine (Pinus massoniana Lamb.) is a major fast-growing woody tree species and pioneer species for afforestation in barren sites in southern China. However, the regulatory mechanism of gene expression in P. massoniana under drought remains unclear. To uncover candidate microRNAs, their expression profiles, and microRNA-mRNA interactions, small RNA-seq was used to investigate the transcriptome from seedling roots under drought and rewatering in P. massoniana. A total of 421 plant microRNAs were identified. Pairwise differential expression analysis between treatment and control groups unveiled 134, 156, and 96 differential expressed microRNAs at three stages. These constitute 248 unique microRNAs, which were subsequently categorized into six clusters based on their expression profiles. Degradome sequencing revealed that these 248 differentially expressed microRNAs targeted 2069 genes. Gene Ontology enrichment analysis suggested that these target genes were related to translational and posttranslational regulation, cell wall modification, and reactive oxygen species scavenging. miRNAs such as miR482, miR398, miR11571, miR396, miR166, miRN88, and miRN74, along with their target genes annotated as F-box/kelch-repeat protein, 60S ribosomal protein, copper-zinc superoxide dismutase, luminal-binding protein, S-adenosylmethionine synthase, and Early Responsive to Dehydration Stress may play critical roles in drought response. This study provides insights into microRNA responsive to drought and rewatering in Masson pine and advances the understanding of drought tolerance mechanisms in Pinus.

Osmotic stress-induced lignin synthesis is regulated at multiple levels in alfalfa (Medicago sativa L.)

Alfalfa is an important forage crop. Yield and quality are frequently threatened by extreme environments such as drought and salt stress. As a component of the cell wall, lignin plays an important role in the abiotic stress response, the mechanisms of which have not been well clarified. In this study, we combined physiological, transcriptional, and metabolic analyses to reveal the changes in lignin content in alfalfa under mannitol-induced osmotic stress. Osmotic stress enhanced lignin accumulation by increasing G and S units, which was associated with increases in enzyme activities and decreases in 8 intermediate metabolites. Upon combined analysis of the transcriptome and metabolome, we identified five key structural genes and several coexpressed transcription factors, such as MYB and WRKY, which may play a core role in regulating lignin content and composition under osmotic stress. In addition, lignin synthesis was positively regulated by ABA but negatively regulated by ethylene under osmotic stress. These results provide new insight into the regulatory mechanism of lignin synthesis under abiotic stress.

Comparative transcriptome profiling to unravel the key molecular signalling pathways and drought adaptive plasticity in shoot borne root system of sugarcane

Sugarcane root system comprises of superficial sett roots as well as deeply-penetrating shoot borne roots (SBR) with latter being the permanent root system. In sugarcane, the healthy SBR contributes to a better crop yield and it also helps to produce multiple ratoon crops after the harvest. There is a dearth of in-depth knowledge on SBR system architecture and its functional role in modern day commercial hybrids. A comprehensive phenotypic, anatomical and whole transcriptome profiling, conducted between the commercial sugarcane hybrids and a wild germplasm Erianthus, found a developmental delay in both initiation and establishment of the SBR in commercial hybrid compared to Erianthus. The SBR system in Erianthus proved to be an extensive drought-adaptive root system architecture that significantly contributes to drought tolerance. On the other hand, SBRs in the commercial hybrids showed an irreversible collapse and damage of the root cells under drought stress. The outcomes from the comparative analysis of the transcriptome data showed a significant upregulation of the genes that regulate important stress signalling pathways viz., sugar, calcium, hormone signalling and phenylpropanoid biosynthesis in the SBRs of Erianthus. It was found that through these key signalling pathways, Erianthus SBRs triggered the downstream signalling cascade to impart physiological responses like osmoprotection, modification of the cell walls, detoxification of reactive oxygen species, expression of drought responsive transcription factors, maintenance of cell stability and lateral root development. The current study forms a basis for further exploration of the Shoot Borne Root system as a valuable breeding target to develop drought tolerant sugarcane genotypes.

Engaging Precision Phenotyping to Scrutinize Vegetative Drought Tolerance and Recovery in Chickpea Plant Genetic Resources

Precise and high-throughput phenotyping (HTP) of vegetative drought tolerance in chickpea plant genetic resources (PGR) would enable improved screening for genotypes with low relative loss of biomass formation and reliable physiological performance. It could also provide a basis to further decipher the quantitative trait drought tolerance and recovery and gain a better understanding of the underlying mechanisms. In the context of climate change and novel nutritional trends, legumes and chickpea in particular are becoming increasingly important because of their high protein content and adaptation to low-input conditions. The PGR of legumes represent a valuable source of genetic diversity that can be used for breeding. However, the limited use of germplasm is partly due to a lack of available characterization data. The development of HTP systems offers a perspective for the analysis of dynamic plant traits such as abiotic stress tolerance and can support the identification of suitable genetic resources with a potential breeding value. Sixty chickpea accessions were evaluated on an HTP system under contrasting water regimes to precisely evaluate growth, physiological traits, and recovery under optimal conditions in comparison to drought stress at the vegetative stage. In addition to traits such as Estimated Biovolume (EB), Plant Height (PH), and several color-related traits over more than forty days, photosynthesis was examined by chlorophyll fluorescence measurements on relevant days prior to, during, and after drought stress. With high data quality, a wide phenotypic diversity for adaptation, tolerance, and recovery to drought was recorded in the chickpea PGR panel. In addition to a loss of EB between 72% and 82% after 21 days of drought, photosynthetic capacity decreased by 16-28%. Color-related traits can be used as indicators of different drought stress stages, as they show the progression of stress.

Genome-wide association study in two-row spring barley landraces identifies QTL associated with plantlets root system architecture traits in well-watered and osmotic stress conditions

Water availability is undoubtedly one of the most important environmental factors affecting crop production. Drought causes a gradual deprivation of water in the soil from top to deep layers and can occur at diverse stages of plant development. Roots are the first organs that perceive water deficit in soil and their adaptive development contributes to drought adaptation. Domestication has contributed to a bottleneck in genetic diversity. Wild species or landraces represent a pool of genetic diversity that has not been exploited yet in breeding program. In this study, we used a collection of 230 two-row spring barley landraces to detect phenotypic variation in root system plasticity in response to drought and to identify new quantitative trait loci (QTL) involved in root system architecture under diverse growth conditions. For this purpose, young seedlings grown for 21 days in pouches under control and osmotic-stress conditions were phenotyped and genotyped using the barley 50k iSelect SNP array, and genome-wide association studies (GWAS) were conducted using three different GWAS methods (MLM GAPIT, FarmCPU, and BLINK) to detect genotype/phenotype associations. In total, 276 significant marker-trait associations (MTAs; p-value (FDR)< 0.05) were identified for root (14 and 12 traits under osmotic-stress and control conditions, respectively) and for three shoot traits under both conditions. In total, 52 QTL (multi-trait or identified by at least two different GWAS approaches) were investigated to identify genes representing promising candidates with a role in root development and adaptation to drought stress.

Modulation of lignin biosynthesis for drought tolerance in plants

Lignin is a complex polymer that is embedded in plant cell walls to provide physical support and water protection. For these reasons, the production of lignin is closely linked with plant adaptation to terrestrial regions. In response to developmental cues and external environmental conditions, plants use an elaborate regulatory network to determine the timing and location of lignin biosynthesis. In this review, we summarize the canonical lignin biosynthetic pathway and transcriptional regulatory network of lignin biosynthesis, consisting of NAC and MYB transcription factors, to explain how plants regulate lignin deposition under drought stress. Moreover, we discuss how the transcriptional network can be applied to the development of drought tolerant plants.

Transcriptome and metabolome analyses of lignin biosynthesis mechanism of Platycladus orientalis

Background

Platycladus orientalis, as an important plant for ecological protection, is a pioneer tree species for afforestation in arid and barren mountainous areas. Lignin has the functions of water and soil conservation, strengthening plant mechanical strength and resisting adverse environmental effects and plays an important role in the ecological protection benefits of P. orientalis.

Methods

In this study, annual dynamic observations of the lignin content in roots, stems and leaves of one-year-old seedlings of a P. orientalis half-sib family were carried out, and combined transcriptome and metabolome analyses were carried out during three key stages of P. orientalis stem development.

Results

The lignin contents in roots, stems and leaves of P. orientalis showed extremely significant spatiotemporal differences. In the stems, lignin was mainly distributed in the cell walls of the pith, xylem, phloem, pericyte, and epidermis, with differences in different periods. A total of 226 metabolites were detected in the stem of P. orientalis, which were divided into seven categories, including 10 synthetic precursor compounds containing lignin. Among them, the content of coniferyl alcohol was the highest, accounting for 12.27% of the total content, and caffeyl alcohol was the lowest, accounting for 7.05% only. By annotating the KEGG functions, a large number of differentially expressed genes and differential metabolites were obtained for the comparison combinations, and seven key enzymes and 24 related genes involved in the process of lignin synthesis in P. orientalis were selected.

Conclusions

Based on the results of the metabolic mechanism of lignin in P. orientalis by biochemical, anatomical and molecular biological analyzes, the key regulatory pathways of lignin in P. orientalis were identified, which will be of great significance for regulating the lignin content of P. orientalis and improving the adaptability and resistance of this plant.

Root plasticity under abiotic stress

Abiotic stresses increasingly threaten existing ecological and agricultural systems across the globe. Plant roots perceive these stresses in the soil and adapt their architecture accordingly. This review provides insights into recent discoveries showing the importance of root system architecture (RSA) and plasticity for the survival and development of plants under heat, cold, drought, salt, and flooding stress. In addition, we review the molecular regulation and hormonal pathways involved in controlling RSA plasticity, main root growth, branching and lateral root growth, root hair development, and formation of adventitious roots. Several stresses affect root anatomy by causing aerenchyma formation, lignin and suberin deposition, and Casparian strip modulation. Roots can also actively grow toward favorable soil conditions and avoid environments detrimental to their development. Recent advances in understanding the cellular mechanisms behind these different root tropisms are discussed. Understanding root plasticity will be instrumental for the development of crops that are resilient in the face of abiotic stress.

Crosstalk between phytohormones and secondary metabolites in the drought stress tolerance of crop plants: A review

Drought stress negatively affects crop performance and weakens global food security. It triggers the activation of downstream pathways, mainly through phytohormones homeostasis and their signaling networks, which further initiate the biosynthesis of secondary metabolites (SMs). Roots sense drought stress, the signal travels to the above-ground tissues to induce systemic phytohormones signaling. The systemic signals further trigger the biosynthesis of SMs and stomatal closure to prevent water loss. SMs primarily scavenge reactive oxygen species (ROS) to protect plants from lipid peroxidation and also perform additional defense-related functions. Moreover, drought-induced volatile SMs can alert the plant tissues to perform drought stress mitigating functions in plants. Other phytohormone-induced stress responses include cell wall and cuticle thickening, root and leaf morphology alteration, and anatomical changes of roots, stems, and leaves, which in turn minimize the oxidative stress, water loss, and other adverse effects of drought. Exogenous applications of phytohormones and genetic engineering of phytohormones signaling and biosynthesis pathways mitigate the drought stress effects. Direct modulation of the SMs biosynthetic pathway genes or indirect via phytohormones' regulation provides drought tolerance. Thus, phytohormones and SMs play key roles in plant development under the drought stress environment in crop plants.

Tartary Buckwheat (Fagopyrum tataricum) NAC Transcription Factors FtNAC16 Negatively Regulates of Pod Cracking and Salinity Tolerant in Arabidopsis

The thick and hard fruit shell of Fagopyrum tataricum (F. tataricum) represents a processing bottleneck. At the same time, soil salinization is one of the main problems faced by modern agricultural production. Bioinformatic analysis indicated that the F. tataricum transcription factor FtNAC16 could regulate the hull cracking of F. tataricum, and the function of this transcription factor was verified by genetic transformation of Arabidopsis thaliana (A. thaliana). Phenotypic observations of the wild-type (WT), OE-FtNAC16, nst1/3 and nst1/3-FtNAC16 plant lines confirmed that FtNAC16 negatively regulated pod cracking by downregulating lignin synthesis. Under salt stress, several physiological indicators (POD, GSH, Pro and MDA) were measured, A. thaliana leaves were stained with NBT (Nitroblue Tetrazolium) and DAB (3,3’-diaminobenzidine), and all genes encoding enzymes in the lignin synthesis pathway were analyzed. These experiments confirmed that FtNAC16 increased plant sensitivity by reducing the lignin content or changing the proportions of the lignin monomer. The results of this study may help to elucidate the possible association between changes in lignin monomer synthesis and salt stress and may also contribute to fully understanding the effects of FtNAC16 on plant growth and development, particularly regarding fruit pod cracking and environmental adaptability. In future studies, it may be useful to obtain suitable cracking varieties and salt-tolerant crops through molecular breeding.

Mycorrhizal Fungi as Bioprotectors of Crops Against Verticillium Wilt-A Hypothetical Scenario Under Changing Environmental Conditions

The association that many crops can establish with the arbuscular mycorrhizal fungi (AMF) present in soils can enhance the resistance of the host plants against several pathogens, including Verticillium spp. The increased resistance of mycorrhizal plants is mainly due to the improved nutritional and water status of crops and to enhanced antioxidant metabolism and/or increased production of secondary metabolites in the plant tissues. However, the effectiveness of AMF in protecting their host plants against Verticillium spp. may vary depending on the environmental factors. Some environmental factors, such as the concentration of carbon dioxide in the atmosphere, the availability of soil water and the air and soil temperatures, are predicted to change drastically by the end of the century. The present paper discusses to what extent the climate change may influence the role of AMF in protecting crops against Verticillium-induced wilt, taking into account the current knowledge about the direct and indirect effects that the changing environment can exert on AMF communities in soils and on the symbiosis between crops and AMF, as well as on the development, incidence and impact of diseases caused by soil-borne pathogens.