The wheat WRKY transcription factor TaWRKY1-2D confers drought resistance in transgenic Arabidopsis and wheat (Triticum aestivum L.)

TaWRKY50-TaSARK7 module-mediated cysteine-rich protein phosphorylation suppresses the programmed cell death response to Chinese wheat mosaic virus infection

WRKY transcription factors are widely involved in plant responses to biotic and abiotic stresses. However, there is currently a limited understanding of the regulation of viral infection by WRKY transcription factors in wheat (Triticum aestivum). The WRKY transcription factor TaWRKY50 in group IIb wheat exhibited a significant response to Chinese wheat mosaic virus infection. TaWRKY50 is localized in the nucleus and is an activating transcription factor. Interestingly, we found that silencing TaWRKY50 induces cell death following inoculation with CWMV. The protein kinase TaSAPK7 is specific to plants, whereas NbSRK is a closely related kinase with high homology to TaSAPK7. The transcriptional activities of both TaSAPK7 and NbSRK can be enhanced by TaWRKY50 binding to their promoters. CRP is an RNA silencing suppressor. Furthermore, TaWRKY50 may regulate CWMV infection by regulating the expression of TaSAPK7 and NbSRK to increase CRP phosphorylation and reduce the amount of programmed cell death (PCD).

Unraveling wheat's response to salt stress during early growth stages through transcriptomic analysis and co-expression network profiling

BACKGROUND

Soil salinization is one of the vital factors threatening the world's food security. To reveal the biological mechanism of response to salt stress in wheat, this study was conducted to resolve the transcription level difference to salt stress between CM6005 (salt-tolerant) and KN9204 (salt-sensitive) at the germination and seedling stage.

RESULTS

To investigate the molecular mechanism underlying salt tolerance in wheat, we conducted comprehensive transcriptome analyses at the seedling and germination stages. Two wheat cultivars, CM6005 (salt-tolerant) and KN9204 (salt-sensitive) were subjected to salt treatment, resulting in a total of 24 transcriptomes. Through expression-network analysis, we identified 17 modules, 16 and 13 of which highly correlate with salt tolerance-related phenotypes in the germination and seedling stages, respectively. Moreover, we identified candidate Hub genes associated with specific modules and explored their regulatory relationships using co-expression data. Enrichment analysis revealed specific enrichment of gibberellin-related terms and pathways in CM6005, highlighting the potential importance of gibberellin regulation in enhancing salt tolerance. In contrast, KN9204 exhibited specific enrichment in glutathione-related terms and activities, suggesting the involvement of glutathione-mediated antioxidant mechanisms in conferring resistance to salt stress. Additionally, glucose transport was found to be a fundamental mechanism for salt tolerance during wheat seedling and germination stages, indicating its potential universality in wheat. Wheat plants improve their resilience and productivity by utilizing adaptive mechanisms like adjusting osmotic balance, bolstering antioxidant defenses, accumulating compatible solutes, altering root morphology, and regulating hormones, enabling them to better withstand extended periods of salt stress.

CONCLUSION

Through utilizing transcriptome-level analysis employing WGCNA, we have revealed a potential regulatory mechanism that governs the response to salt stress and recovery in wheat cultivars. Furthermore, we have identified key candidate central genes that play a crucial role in this mechanism. These central genes are likely to be vital components within the gene expression network associated with salt tolerance. The findings of this study strongly support the molecular breeding of salt-tolerant wheat, particularly by utilizing the genetic advancements based on CM6005 and KN9204.

Zmhdz9, an HD-Zip transcription factor, promotes drought stress resistance in maize by modulating ABA and lignin accumulation

Maize is the largest crop in the world in terms of both planting area and total yield, and it plays a crucial role in ensuring global food and feed security. However, in recent years, with climate deterioration, environmental changes, and the scarcity of freshwater resources, drought has become a serious limiting factor for maize yield and quality. Drought stress-induced signals undergo a series of transmission processes to regulate the expression of specific genes, thereby affecting the drought tolerance of plants at the tissue, cellular, physiological and biochemical levels. Therefore, in this study we investigated the HD-Zip transcription factor gene Zmhdz9, and yeast activation experiments demonstrated that Zmhdz9 exhibited transcriptional activation activity. Under drought stress, high abscisic acid (ABA) and lignin levels significantly improved drought resistance in maize. Yeast two-hybrid, bimolecular fluorescence complementation (BIFC) and pull-down experiments showed that Zmhdz9 interacted with ZmWRKY120 and ZmTCP9, respectively. Overexpression of Zmhdz9 and gene editing of ZmWRKY120 or ZmTCP9 improved maize drought resistance, indicating their importance in the drought stress response. Furthermore, Zmhdz9 promoted the direct transcription of ZmWRKY120 in the W-box, activating elements of the ZmNCED1 promoter, which encodes a key enzyme in ABA biosynthesis. Additionally, Zmhdz9 promoted direct transcription of ZmTCP9 in the GGTCA motif, activating elements of the ZmKNOX8 promoter, which encodes a key enzyme in lignin synthesis. This study showed that the regulation of ABA and lignin by Zmhdz9 is essential for drought stress resistance in maize.

Transcriptome Analysis Reveals Drought-Responsive Pathways and Key Genes of Two Oat (Avena sativa) Varieties

To cope with the yield loss caused by drought stress, new oat varieties with greater drought tolerance need to be selected. In this study, two oat varieties with different drought tolerances were selected for analysis of their phenotypes and physiological indices under moderate and severe soil drought stress. The results revealed significant differences in the degree of wilting, leaf relative water content (RWC), and SOD and CAT activity between the two oat genotypes under severe soil drought stress; moreover, the drought-tolerant variety exhibited a significant increase in the number of stomata and wax crystals on the surface of both the leaf and guard cells; additionally, the morphology of the guard cells was normal, and there was no significant disruption of the grana lamella membrane or the nuclear envelope. Furthermore, transcriptome analysis revealed that the expression of genes related to the biosynthesis of waxes and cell-wall components, as well as those of the WRKY family, significantly increased in the drought-tolerant variety. These findings suggest that several genes involved in the antioxidant pathway could improve drought tolerance in plants by regulating the increase/decrease in wax and cell-wall constituents and maintaining normal cellular water potential, as well as improving the ability of the antioxidant system to scavenge peroxides in oats.

Wheat adaptation to environmental stresses under climate change: Molecular basis and genetic improvement

Wheat (Triticum aestivum) is a staple food for about 40% of the world's population. As the global population has grown and living standards improved, high yield and improved nutritional quality have become the main targets for wheat breeding. However, wheat production has been compromised by global warming through the more frequent occurrence of extreme temperature events, which have increased water scarcity, aggravated soil salinization, caused plants to be more vulnerable to diseases, and directly reduced plant fertility and suppressed yield. One promising option to address these challenges is the genetic improvement of wheat for enhanced resistance to environmental stress. Several decades of progress in genomics and genetic engineering has tremendously advanced our understanding of the molecular and genetic mechanisms underlying abiotic and biotic stress responses in wheat. These advances have heralded what might be considered a "golden age" of functional genomics for the genetic improvement of wheat. Here, we summarize the current knowledge on the molecular and genetic basis of wheat resistance to abiotic and biotic stresses, including the QTLs/genes involved, their functional and regulatory mechanisms, and strategies for genetic modification of wheat for improved stress resistance. In addition, we also provide perspectives on some key challenges that need to be addressed.

Metabolic pathways engineering for drought or/and heat tolerance in cereals

Drought (D) and heat (H) are the two major abiotic stresses hindering cereal crop growth and productivity, either singly or in combination (D/+H), by imposing various negative impacts on plant physiological and biochemical processes. Consequently, this decreases overall cereal crop production and impacts global food availability and human nutrition. To achieve global food and nutrition security vis-a-vis global climate change, deployment of new strategies for enhancing crop D/+H stress tolerance and higher nutritive value in cereals is imperative. This depends on first gaining a mechanistic understanding of the mechanisms underlying D/+H stress response. Meanwhile, functional genomics has revealed several stress-related genes that have been successfully used in target-gene approach to generate stress-tolerant cultivars and sustain crop productivity over the past decades. However, the fast-changing climate, coupled with the complexity and multigenic nature of D/+H tolerance suggest that single-gene/trait targeting may not suffice in improving such traits. Hence, in this review-cum-perspective, we advance that targeted multiple-gene or metabolic pathway manipulation could represent the most effective approach for improving D/+H stress tolerance. First, we highlight the impact of D/+H stress on cereal crops, and the elaborate plant physiological and molecular responses. We then discuss how key primary metabolism- and secondary metabolism-related metabolic pathways, including carbon metabolism, starch metabolism, phenylpropanoid biosynthesis, γ-aminobutyric acid (GABA) biosynthesis, and phytohormone biosynthesis and signaling can be modified using modern molecular biotechnology approaches such as CRISPR-Cas9 system and synthetic biology (Synbio) to enhance D/+H tolerance in cereal crops. Understandably, several bottlenecks hinder metabolic pathway modification, including those related to feedback regulation, gene functional annotation, complex crosstalk between pathways, and metabolomics data and spatiotemporal gene expressions analyses. Nonetheless, recent advances in molecular biotechnology, genome-editing, single-cell metabolomics, and data annotation and analysis approaches, when integrated, offer unprecedented opportunities for pathway engineering for enhancing crop D/+H stress tolerance and improved yield. Especially, Synbio-based strategies will accelerate the development of climate resilient and nutrient-dense cereals, critical for achieving global food security and combating malnutrition.

The Transcription Factor MbWRKY46 in Malus baccata (L.) Borkh Mediate Cold and Drought Stress Responses

The living environment of plants is not static; as such, they will inevitably be threatened by various external factors for their growth and development. In order to ensure the healthy growth of plants, in addition to artificial interference, the most important and effective method is to rely on the role of transcription factors in the regulatory network of plant responses to abiotic stress. This study conducted bioinformatics analysis on the MbWRKY46 gene, which was obtained through gene cloning technology from Malus baccata (L.) Borkh, and found that the MbWRKY46 gene had a total length of 1068 bp and encodes 355 amino acids. The theoretical molecular weight (MW) of the MbWRKY46 protein was 39.76 kDa, the theoretical isoelectric point (pI) was 5.55, and the average hydrophilicity coefficient was -0.824. The subcellular localization results showed that it was located in the nucleus. After conducting stress resistance studies on it, it was found that the expression of MbWRKY46 was tissue specific, with the highest expression level in roots and old leaves. Low temperature and drought had a stronger induction effect on the expression of this gene. Under low temperature and drought treatment, the expression levels of several downstream genes related to low temperature and drought stress (AtKIN1, AtRD29A, AtCOR47A, AtDREB2A, AtERD10, AtRD29B) increased more significantly in transgenic Arabidopsis. This indicated that MbWRKY46 gene can be induced to upregulate expression in Arabidopsis under cold and water deficient environments. The results of this study have a certain reference value for the application of M. baccata MbWRKY46 in low-temperature and drought response, and provide a theoretical basis for further research on its function in the future.

Analysis of Raffinose Synthase Gene Family in Bread Wheat and Identification of Drought Resistance and Salt Tolerance Function of TaRS15-3B

Raffinose synthase (RS) plays a crucial role in plant growth and development, as well as in responses to biotic stresses and abiotic stresses, yet few studies have been conducted on its role in bread wheat. Therefore, in this study we screened and identified a family of bread wheat raffinose synthase genes based on bread wheat genome information and analyzed their physicochemical properties, phylogenetic evolutionary relationships, conserved structural domains, promoter cis-acting elements, and expression patterns. The BSMV-induced silencing of TaRS15-3B resulted in the bread wheat seedlings being susceptible to drought and salt stress and reduced the expression levels of stress-related and ROS-scavenging genes in bread wheat plants. This further affected the ability of bread wheat to cope with drought and salt stress. In conclusion, this study revealed that the RS gene family in bread wheat plays an important role in plant response to abiotic stresses and that the TaRS15-3B gene can improve the tolerance of transgenic bread wheat to drought and salt stresses, provide directions for the study of other RS gene families in bread wheat, and supply candidate genes for use in molecular breeding of bread wheat for stress resistance.

Duplicate Genes Contribute to Variability in Abiotic Stress Resistance in Allopolyploid Wheat

Gene duplication is a universal biological phenomenon that drives genomic variation and diversity, plays a crucial role in plant evolution, and contributes to innovations in genetic engineering and crop development. Duplicated genes participate in the emergence of novel functionality, such as adaptability to new or more severe abiotic stress resistance. Future crop research will benefit from advanced, mechanistic understanding of the effects of gene duplication, especially in the development and deployment of high-performance, stress-resistant, elite wheat lines. In this review, we summarize the current knowledge of gene duplication in wheat, including the principle of gene duplication and its effects on gene function, the diversity of duplicated genes, and how they have functionally diverged. Then, we discuss how duplicated genes contribute to abiotic stress response and the mechanisms of duplication. Finally, we have a future prospects section that discusses the direction of future efforts in the short term regarding the elucidation of replication and retention mechanisms of repetitive genes related to abiotic stress response in wheat, excellent gene function research, and practical applications.

Progress in the understanding of WRKY transcription factors in woody plants

The WRKY transcription factor (TF) family, named for its iconic WRKY domain, is among the largest and most functionally diverse TF families in higher plants. WRKY TFs typically interact with the W-box of the target gene promoter to activate or inhibit the expression of downstream genes; these TFs are involved in the regulation of various physiological responses. Analyses of WRKY TFs in numerous woody plant species have revealed that WRKY family members are broadly involved in plant growth and development, as well as responses to biotic and abiotic stresses. Here, we review the origin, distribution, structure, and classification of WRKY TFs, along with their mechanisms of action, the regulatory networks in which they are involved, and their biological functions in woody plants. We consider methods currently used to investigate WRKY TFs in woody plants, discuss outstanding problems, and propose several new research directions. Our objective is to understand the current progress in this field and provide new perspectives to accelerate the pace of research that enable greater exploration of the biological functions of WRKY TFs.

Transcriptome Analysis of Roots from Wheat (Triticum aestivum L.) Varieties in Response to Drought Stress

Under climate change, drought is one of the most limiting factors that influences wheat (Triticum aestivum L.) production. Exploring stress-related genes is vital for wheat breeding. To identify genes related to the drought tolerance response, two common wheat cultivars, Zhengmai 366 (ZM366) and Chuanmai 42 (CM42), were selected based on their obvious difference in root length under 15% PEG-6000 treatment. The root length of the ZM366 cultivar was significantly longer than that of CM42. Stress-related genes were identified by RNA-seq in samples treated with 15% PEG-6000 for 7 days. In total, 11,083 differentially expressed genes (DEGs) and numerous single nucleotide polymorphisms (SNPs) and insertions/deletions (InDels) were identified. GO enrichment analysis revealed that the upregulated genes were mainly related to the response to water, acidic chemicals, oxygen-containing compounds, inorganic substances, and abiotic stimuli. Among the DEGs, the expression levels of 16 genes in ZM366 were higher than those in CM42 after the 15% PEG-6000 treatment based on RT-qPCR. Furthermore, EMS-induced mutants in Kronos (T. turgidum L.) of 4 representative DEGs possessed longer roots than the WT after the 15% PEG-6000 treatment. Altogether, the drought stress genes identified in this study represent useful gene resources for wheat breeding.

Full-length transcriptome of in Medicago sativa L. roots in response to drought stress

Background: Alfalfa (Medicago sativa L.), serves as a legume with high drought tolerance, is a major forage crop with a high biomass of production. However, the molecular mechanism of Alfalfa in response to drought stress are still unclear. Results: We constructed the first full-length transcriptome for Alfalfa root. 21.53Gb clean data were obtained by further data filtering, in which incorporate 566,076 reads of Insert (ROI), and 409,291 full length reads non-Chimeric (FLNC) sequences. Combined with second-generation sequencing (SGS), there were 2615, 6011, and 4617 differentially expressed genes (DEGs) in three comparisons. KEGG pathway analysis showed enrichment of ribosome, glutathione metabolism, and biosynthesis of amino acids are among the DEGs. The majority of transcription factors (TFs) from DEGs were AP2/ERF-ERF (37), C2H2 (32), and bHLH (22) bZIP (22), followed by C3H (19), MYB (18), WRKY (18), GRAS (16), and NAC (15). 32 C2H2 genes were differentially expressed in three groups. In addition, TFs annotated as C3H (19), MYB (18), GRAS (16), and NAC (15) also changed significantly in expression in the three comparisons. We found 24 genes participate in the abscisic acid (ABA) and auxin hormone signaling pathway in response to drought stress, and monitored the expression patterns of these related genes. Conclusion: The present study enhanced our understanding of the genetic diversity and complexity, and provides greater insight into the fundamental transcriptome reprogramming of Alfalfa under drought.