The PtoERF1‐PtomiR393a‐PtoFBL4 module confers drought tolerance via ABA–auxin crosstalk in Populus

NpWRKY38 Negatively Regulates Drought Tolerance by Impairing ABA/SA Signaling as Well as Photosynthesis in Narenga porphyrocoma

Narenga porphyrocoma, a wild relative of sugarcane with high drought tolerance, is a valuable germplasm resource for mining drought-tolerance genes. Weighted gene co-expression network analysis (WGCNA) identified NpWRKY38, a WRKY transcription factor that was significantly down-regulated under drought stress, a response that was further recapitulated by exogenous abscisic acid (ABA) treatment and consistent with the presence of ABA-responsive elements in its promoter. NpWRKY38 overexpression in rice resulted in a significant increase in endogenous ABA content, yet led to insufficient stomatal closure, an attenuated response to exogenous ABA, and a significant reduction in drought tolerance. Transcriptomic analysis revealed that stress-related signaling pathways (e.g., MAPK signaling and plant hormone signal transduction) were activated in the OE lines, whereas photosynthesis, carbon fixation, and chlorophyll biosynthesis pathways were globally suppressed. Specifically, the ABA biosynthetic gene NCED was up-regulated, whereas the positive signaling regulator ABI5 was down-regulated and the negative regulator PP2C was up-regulated, thereby impairing ABA signal transduction. In addition, genes involved in salicylic acid (SA) biosynthesis and signaling (PAL, C4H, NPR4, WRKY45) were broadly down-regulated concurrently with reduced antioxidant enzyme activities. Furthermore, NpWRKY38 overexpression exacerbated drought-induced chloroplast damage, as evidenced by a greater reduction in SPAD values and severe chloroplast ultrastructural abnormalities, including swelling, disorganized thylakoid lamellae, and disrupted grana. These three pathways, namely impaired ABA/SA signaling, suppressed photosynthesis, and chloroplast damage, collectively exacerbated the drought-sensitive phenotype of the OE lines. This study demonstrates that NpWRKY38 acts as a multi-pathway negative regulatory mechanism by interfering with ABA signal transduction, suppressing the SA pathway, down-regulating photosynthetic genes, and compromising chloroplast integrity, providing a potential target for drought tolerance breeding in sugarcane.

The bp-miR156c–BpSPL2 module positively regulates drought tolerance by mediating lateral root development and reactive oxygen species scavenging in Betula platyphylla

The PtARF6/PtARF8-PtGH3.1 transcriptional module regulates auxin homeostasis and dwarfism in citrus.

An integrated multi-omics analysis of dwarf and normal-height red tangerine × trifoliate orange hybrid seedlings revealed a PtARF6/8-PtGH3.1 transcriptional module that regulates auxin homeostasis through IAA conjugation, providing genetic insights into GH3.1-mediated dwarfism.

The CsTBH-CsROP2 Module Regulates Waterlogging Tolerance via Auxin-Mediated Adventitious Root Formation in Cucumber.

Cucumber (Cucumis sativus L.) requires frequent irrigation due to its shallow root system and high transpiration rate of the aboveground parts. However, it is also prone to waterlogging damage. Therefore, understanding its response to waterlogging is crucial for breeding waterlogging-tolerant varieties. Although Rho of Plants GTPases play well-established roles in regulating development and stress signalling, their functions in plant adaptation to waterlogging stress has yet to be fully elucidated. Here, we identified nine CsROP genes in the cucumber genome, which exhibit evolutionary diversification but retain conserved functional domains. Functional analysis revealed that CsROP2 acts as a negative regulator of adventitious root formation. It modulates auxin accumulation in hypocotyl vascular bundles, thereby suppressing adventitious root development and enhancing waterlogging sensitivity. The HD-Zip I transcription factor CsTBH directly binds the CsROP2 promoter and activates its expression. Our study uncovers a CsTBH-CsROP2 module that governs adventitious rooting and waterlogging tolerance by modulating auxin homeostasis. These findings provide new insights into the crosstalk between developmental programmes and stress signalling pathways and offer potential genetic targets for improving stress resilience in cucumber and other crops.

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 DlamiR156-DlaSPL60-DlaP5CS1 cascade directly regulates proline synthesis, conferring drought tolerance in Ma bamboo (Dendrocalamus latiflorus Munro).

Drought stress disrupts cellular homeostasis and severely limits plant growth. Although proline accumulation is a major adaptive response to water deficit, how drought-responsive regulatory networks control proline biosynthesis in woody grasses remains poorly understood. Here, we combined genetic manipulation, molecular assays, and physiological analyses to investigate the function of the DlamiR156-DlaSPL60 module in Ma bamboo (Dendrocalamus latiflorus Munro). We show that DlamiR156 acts as a negative regulator of drought tolerance by repressing DlaSPL60 via transcript cleavage, whereas drought-induced reduction of DlamiR156 releases this repression; DlaSPL60 directly binds to the DlaP5CS1 promoter and activates its transcription, thereby promoting proline accumulation. Our findings establish a mechanistic link between the conserved miR156-squamosa promoter-binding protein-like regulatory module and proline biosynthesis in bamboo, providing new insights into how post-transcriptional regulation coordinates metabolic reprogramming during drought adaptation in perennial woody grasses.