The transcription factor ZmMYB3R targets CYCB1;2 to modulate maize drought tolerance.

The R2R3-MYB transcription factor ScMYB20 negatively regulates drought and salt tolerance through a dual-repression of ScCHALCONE SYNTHASE-1 (ScCHS1)-mediated flavonoid biosynthesis in the desert moss Syntrichia caninervis.

The OsRFP1-OsMYB61 module regulates rice drought tolerance by modulating the transcription of ABA- and drought-responsive genes.

Rice (Oryza sativa L.) is a major food crop worldwide. With the acceleration of global warming, drought is becoming one of the major limitations for rice productivity. In plants, MYB transcription factors (TF) play pivotal roles in mediating drought stress tolerance. The rice OsMYB61 encodes an R2R3-MYB protein. OsMYB61 is localized both in the nucleus and the stomatal guard cells in the Nicotiana benthamiana leaves. The expression of OsMYB61 is repressed by ABA and PEG treatments. OsMYB61-overexpressing rice lines exhibited decreased drought tolerance. qRT-PCR evidence showed that the transcription levels of OsDREB2A and OsNCED1/4 in transgenic rice plants were differentially altered by PEG treatment. The yeast one-hybrid (Y1H) assay and transient luciferase reporter experiments demonstrated that OsMYB61 may bind to the promoters OsNCED1/4 and OsDREB2A, and hence inhibits their expression. OsRFP1 is a RING-finger E3 ubiquitin ligase and promotes stomatal opening. Our evidence showed that OsMYB61 interacts with and ubiquitinates OsRFP1 directly, thereby promoting its degradation via the ubiquitin-26S proteasome pathway. Moreover, knockout of OsRFP1 via the CRISPR-Cas9 technique led to decreased drought and osmotic tolerance of osrfp1 mutants, implying that OsRFP1 positively regulates drought and osmotic stress response. Furthermore, co-expression of OsRFP1 and OsMYB61 attenuated the repressive effects of OsMYB61 on the transcription of OsNCED1/4 and OsDREB2A. Collectively, our findings unraveled the molecular mechanisms of the OsRFP1-OsMYB61 module in regulating rice drought tolerance, which provide potential targets for rice breeding with improved drought tolerance.

Maize ZmBES1/BZR1-7 Transcription Factor Positively Regulates Drought Tolerance in Transgenic Arabidopsis and Rice

Drought stress significantly limits agricultural productivity and threatens food security. The identification of drought tolerance genes and the dissection of their regulatory networks in crops are crucial for ensuring future food production. The BRI1-EMS1 suppressor (BES1)/brassinazole-resistant 1 (BZR1) family is a kind of plant-specific transcription factor that regulates growth, development, and stress responses in plants. Here, the maize ZmBES1/BZR1-7 gene was cloned and transformed into Arabidopsis and rice to characterize plant phenotypes under drought stress conditions. Sequence analysis revealed that the ZmBES1/BZR1-7 protein contains a conserved basic helix-loop-helix (bHLH) domain, localizes to the nucleus, and exhibits transcriptional activation activity. Expression profiling revealed that ZmBES1/BZR1-7 is induced by drought stress in maize. Overexpression of ZmBES1/BZR1-7 significantly enhanced drought tolerance in both transgenic Arabidopsis and rice. Under drought stress conditions, all transgenic lines showed higher survival rates and relative water content (RWC), increased root length, reduced relative electrolyte leakage (REL) and malondialdehyde (MDA) content, as well as higher yield of transgenic rice than the wild type. Integrated analyses of RNA-seq and qRT-PCR assays demonstrated that ZmBES1/BZR1-7 modulates transcription of stress-responsive genes to enhance drought tolerance. Collectively, the study provides insights into the molecular mechanisms by which ZmBES1/BZR1-7 mediated drought stress response in maize.

Identification of salt and drought resistance function of maize transcription factor ZmEREB54

This study establishes a solid foundation for further clarifying the biological functions and molecular mechanisms of ZmEREB54 in regulating maize root growth and development, as well as responding to drought and salt stresses.

Converging GWAS and Genome Editing Decrypts MsCBF8‐ MsGolS2 Regulatory Module for Drought Tolerance Without Yield Penalty in Medicago sativa

ABSTRACT Drought constitutes a major abiotic stress limiting alfalfa productivity. To elucidate the genetic basis of drought tolerance, a genome‐wide association study (GWAS) was conducted in alfalfa, which identified a CBF/DREB1 family transcription factor designated MsCBF8. Utilizing an optimized CRISPR‐Cas9 system, mutants were successfully generated in the complex autotetraploid background. Combined with overexpression and Arabidopsis complementation assays, this confirmed that MsCBF8 functions as a positive regulator of drought tolerance, with its overexpression enhancing drought tolerance without compromising plant growth. Physiological analyses revealed that MsCBF8 improves drought tolerance by coordinating antioxidant defence (elevated SOD and CAT activities, decreased H2O2 and MDA contents), dynamically regulating stomatal movement (increased water‐use efficiency), and maintaining photosynthetic performance. At the molecular level, MsCBF8 directly and specifically binds to the GCCGAC cis‐element in the MsGolS2 promoter and activates its expression. Silencing MsGolS2 via virus‐induced gene silencing (VIGS) reduced drought tolerance and aggravated oxidative damage, providing the first functional evidence for the essential role of this gene in the drought response of alfalfa. This study systematically elucidates a novel MsCBF8‐MsGolS2 regulatory module, offering crucial insights into the drought adaptation mechanisms in alfalfa and providing valuable genetic resources and breeding targets for developing high‐yield, water‐efficient and drought‐tolerant alfalfa cultivars.

The role of MYB21 in jasmonate-mediated processes in Arabidopsis: transcending flower-specific functions to vegetative tissue.

Jasmonic acid (JA) and its derivatives are lipid-derived phytohormones that coordinate plant growth, development, and stress responses through the bioactive conjugate jasmonoyl-isoleucine (JA-Ile). Their role in reproductive development is well established, particularly in stamen maturation through the R2R3-MYB transcription factor MYB21, which has been considered largely flower-specific. Here, we reveal a previously unrecognized role of MYB21 in vegetative tissues of Arabidopsis thaliana. Although basal MYB21 transcript levels in leaves are extremely low and spatially restricted, wounding and exogenous hormone applications induced MYB21 transcription in a JA- and COI1-dependent manner. Transcriptional GUS reporter analyses showed localized MYB21 promoter activity in specialized epidermal cells, including trichomes, hydathodes, and in the vasculature at wound sites. Functional characterization using the myb21-5 mutant indicated roles in germination and vegetative growth, partially phenocopying JA-insensitive mutants despite unaltered JA biosynthesis and signaling. Transcriptome profiling further revealed changes in expression of genes involved in lignin biosynthesis, light-harvesting complex components, cytokinin pathways, and defense-related responses, consistent with reduced resistance of myb21-5 to insect herbivory and infection by Botrytis cinerea. Together, these findings identify MYB21 as a JA-responsive regulator of growth and defense in seedlings and leaves, extending its function beyond reproductive development.