Systematic analysis of SmWD40s, and responding of SmWD40-170 to drought stress by regulation of ABA- and H2O2-induced stomal movement in Salvia miltiorrhiza bunge

RING-type E3 ligase BnaJUL1 ubiquitinates and degrades BnaTBCC1 to regulate drought tolerance in Brassica napus L

Drought stress poses a persistent threat to field crops and significantly limits global agricultural productivity. Plants employ ubiquitin-dependent degradation as a crucial post-translational regulatory mechanism to swiftly adapt to changing environmental conditions. JUL1 is a RING-type E3 ligase related to drought stress in Arabidopsis. In this study, we explored the function of BnaJUL1 (a homologous gene of JUL1 in Brassica napus) and discovered a novel gene BnaTBCC1 participating in drought tolerance. First, we utilised BnaJUL1-cri materials through the clustered regularly interspaced short palindromic repeats (CRISPR)-CRISPR-associated protein 9 system. Second, we confirmed that BnaJUL1 regulated drought tolerance through the drought tolerance assay and transcriptome analysis. Then, we identified a series of proteins interacting with BnaJUL1 through yeast library screening, including BnaTBCC1 (a tubulin binding cofactor C domain-containing protein); whose homologous gene TBCC1 knockdown mutants (tbcc1-1) exhibited ABA-sensitive germination in Arabidopsis, we then confirmed the involvement of BnaTBCC1 in drought tolerance in both Arabidopsis and Brassica. Finally, we established that BnaJUL1 could ubiquitinate and degrade BnaTBCC1 to regulate drought tolerance. Consequently, our study unveils BnaJUL1 as a novel regulator that ubiquitinates and degrades BnaTBCC1 to modulate drought tolerance and provided desirable germplasm for further breeding of drought tolerance in rapeseed.

Genome-wide analysis of WD40 protein family and functional characterization of BvWD40-82 in sugar beet

Sugar beet is one of the most important sugar crops in the world. It contributes greatly to the global sugar production, but salt stress negatively affects the crop yield. WD40 proteins play important roles in plant growth and response to abiotic stresses through their involvement in a variety of biological processes, such as signal transduction, histone modification, ubiquitination, and RNA processing. The WD40 protein family has been well-studied in Arabidopsis thaliana, rice and other plants, but the systematic analysis of the sugar beet WD40 proteins has not been reported. In this study, a total of 177 BvWD40 proteins were identified from the sugar beet genome, and their evolutionary characteristics, protein structure, gene structure, protein interaction network and gene ontology were systematically analyzed to understand their evolution and function. Meanwhile, the expression patterns of BvWD40s under salt stress were characterized, and a BvWD40-82 gene was hypothesized as a salt-tolerant candidate gene. Its function was further characterized using molecular and genetic methods. The result showed that BvWD40-82 enhanced salt stress tolerance in transgenic Arabidopsis seedlings by increasing the contents of osmolytes and antioxidant enzyme activities, maintaining intracellular ion homeostasis and increasing the expression of genes related to SOS and ABA pathways. The result has laid a foundation for further mechanistic study of the BvWD40 genes in sugar beet tolerance to salt stress, and it may inform biotechnological applications in improving crop stress resilience.

Histone Deacetylases HD2A and HD2B Undergo Feedback Regulation by ABA and Modulate Drought Tolerance via Mediating ABA-Induced Transcriptional Repression

Histone deacetylation catalyzed by histone deacetylase plays a critical role in gene silencing and subsequently controls many important biological processes. It was reported that the expression of the plant-specific histone deacetylase subfamily HD2s is repressed by ABA in Arabidopsis. However, little is known about the molecular relationship between HD2A/HD2B and ABA during the vegetative phase. Here, we describe that the hd2ahd2b mutant shows hypersensitivity to exogenous ABA during the germination and post-germination period. Additionally, transcriptome analyses revealed that the transcription of ABA-responsive genes was reprogrammed and the global H4K5ac level is specifically up-regulated in hd2ahd2b plants. ChIP-Seq and ChIP-qPCR results further verified that both HD2A and HD2B could directly and specifically bind to certain ABA-responsive genes. As a consequence, Arabidopsis hd2ahd2b plants displayed enhanced drought resistance in comparison to WT, which is consistent with increased ROS content, reduced stomatal aperture, and up-regulated drought-resistance-related genes. Moreover, HD2A and HD2B repressed ABA biosynthesis via the deacetylation of H4K5ac at NCED9. Taken together, our results indicate that HD2A and HD2B partly function through ABA signaling and act as negative regulators during the drought resistance response via the regulation of ABA biosynthesis and response genes.

Molecular mechanism of mulberry response to drought stress revealed by complementary transcriptomic and iTRAQ analyses

BACKGROUND

The use of mulberry leaves has long been limited to raising silkworms, but with the continuous improvement of mulberry (Morus alba) resource development and utilization, various mulberry leaf extension products have emerged. However, the fresh leaves of mulberry trees have a specific window of time for picking and are susceptible to adverse factors, such as drought stress. Therefore, exploring the molecular mechanism by which mulberry trees resist drought stress and clarifying the regulatory network of the mulberry drought response is the focus of the current work.

RESULTS

In this study, natural and drought-treated mulberry grafted seedlings were used for transcriptomic and proteomic analyses (CK vs. DS9), aiming to clarify the molecular mechanism of the mulberry drought stress response. Through transcriptome and proteome sequencing, we identified 9889 DEGs and 1893 DEPs enriched in stress-responsive GO functional categories, such as signal transducer activity, antioxidant activity, and transcription regulator activity. KEGG enrichment analysis showed that a large number of codifferentially expressed genes were enriched in flavonoid biosynthesis pathways, hormone signalling pathways, lignin metabolism and other pathways. Through subsequent cooperation analysis, we identified 818 codifferentially expressed genes in the CK vs. DS9 comparison group, including peroxidase (POD), superoxide dismutase (SOD), aldehyde dehydrogenase (ALDHs), glutathione s-transferase (GST) and other genes closely related to the stress response. In addition, we determined that the mulberry gene MaWRKYIII8 (XP_010104968.1) underwent drought- and abscisic acid (ABA)-induced expression, indicating that it may play an important role in the mulberry response to drought stress.

CONCLUSIONS

Our research shows that mulberry can activate proline and ABA biosynthesis pathways and produce a large amount of proline and ABA, which improves the drought resistance of mulberry. MaWRKYIII8 was up-regulated and induced by drought and exogenous ABA, indicating that MaWRKYIII8 may be involved in the mulberry response to drought stress. These studies will help us to analyse the molecular mechanism underlying mulberry drought tolerance and provide important gene information and a theoretical basis for improving mulberry drought tolerance through molecular breeding in the future.

Reactive oxygen species and nitric oxide as mediators in plant hypersensitive response and stomatal closure

Nitric oxide (NO) and reactive oxygen species (ROS) have attracted considerable interest from plant pathologists since they regulate plant defenses via the hypersensitive response (HR) and stomatal closure. Here, we introduce the regulatory mechanisms of NO and ROS bursts and discuss the role of such bursts in HR and stomatal closure. It showed that epidermal sections of leaves respond to pathogens by the rapid and intense production of intracellular ROS and NO. Oxidative stress and H₂O₂ induce stomatal closure. Catalase and peroxidase-deficient plants are also hyperresponsive to pathogen invasion, suggesting a role for H₂O₂ in HR-mediated cell death. The analysis reveals that ROS and NO play important roles in stomatal closure and HR that involves multiple pathways. Therefore, multi-disciplinary and multi-omics combined analysis is crucial to the advancement of ROS and NO research and their role in plant defense mechanism.

Genome-Wide Identification of the TIFY Family in Salvia miltiorrhiza Reveals That SmJAZ3 Interacts With SmWD40-170, a Relevant Protein That Modulates Secondary Metabolism and Development

Salvia miltiorrhiza Bunge (S. miltiorrhiza), a traditional Chinese medicinal herb, contains numerous bioactive components with broad range of pharmacological properties. By increasing the levels of endogenous jasmonate (JA) in plants or treating them with methyl jasmonate (MeJA), the level of tanshinones and salvianolic acids can be greatly enhanced. The jasmonate ZIM (JAZ) proteins belong to the TIFY family, and act as repressors, releasing targeted transcriptional factors in the JA signaling pathway. Herein, we identified and characterized 15 TIFY proteins present in S. miltiorrhiza. Quantitative reverse transcription PCR analysis indicated that the JAZ genes were all constitutively expressed in different tissues and were induced by MeJA treatments. SmJAZ3, which negatively regulates the tanshinones biosynthesis pathway in S. miltiorrhiza and the detailed molecular mechanism is poorly understood. SmJAZ3 acts as a bait protein to capture and identify a WD-repeat containing the protein SmWD40-170. Further molecular and genetic analysis revealed that SmWD40-170 is a positive regulator, promoting the accumulation of secondary metabolites in S. miltiorrhiza. Our study systematically analyzed the TIFY family and speculated a module of the JAZ-WD40 complex provides new insights into the mechanisms regulating the biosynthesis of secondary metabolites in S. miltiorrhiza.

Plant Nitric Oxide Signaling under Drought Stress

Water deficit caused by drought is a significant threat to crop growth and production. Nitric oxide (NO), a water- and lipid-soluble free radical, plays an important role in cytoprotection. Apart from a few studies supporting the role of NO in drought responses, little is known about this pivotal molecular amendment in the regulation of abiotic stress signaling. In this review, we highlight the knowledge gaps in NO roles under drought stress and the technical challenges underlying NO detection and measurements, and we provide recommendations regarding potential avenues for future investigation. The modulation of NO production to alleviate abiotic stress disturbances in higher plants highlights the potential of genetic manipulation to influence NO metabolism as a tool with which plant fitness can be improved under adverse growth conditions.