A MeJA-responsive DoMYB41-DoMYC2 cascade that iteratively activates DoTIP1–1 expression and promotes the biosynthesis of GMs, thereby enhancing salinity tolerance in D. officinale is uncovered and provides genetic targets for salinity tolerance in breeding programs for this horticultural orchid.
Abstract
Soil salinization limits the yield and quality of Dendrobium officinale. The molecular mechanisms linking methyl jasmonate (MeJA) signaling to the biosynthesis of glucomannans (GMs) under salinity remain unclear. In the WGCNA of MeJA- and salinity-treated D. officinale transcriptome, an R2R3-MYB transcription factor was identified, DoMYB41, which was highly expressed in stems and induced by both treatments. Overexpression of DoMYB41 in PLBs increased GMs and anthocyanin, enhanced the activities of antioxidant enzymes, reduced oxidative damage, and elevated relative water content, whereas CRISPR/Cas9 knockout lines showed opposite phenotypes. Transcriptomic analysis identified DoTIP1–1 as a key downstream target, and biochemical assays (dual-LUC, Y1H, EMSA) confirmed that DoMYB41 activates DoTIP1–1 transcription by directly targeting the MBS motif present in its promoter. Furthermore, DoMYB41 physically interacted with the bHLH transcription factor DoMYC2, which alone bound to and activated the promoters of both DoTIP1–1 and DoMYB41, forming a positive feedback loop. Intriguingly, DoMYB41 and DoMYC2 synergistically activated DoTIP1–1. These findings uncovered a MeJA-responsive DoMYB41-DoMYC2 cascade that iteratively activates DoTIP1–1 expression and promotes the biosynthesis of GMs, thereby enhancing salinity tolerance in D. officinale. This study also provides genetic targets for salinity tolerance in breeding programs for this horticultural orchid.
It is shown that salt stress–induced ABA accumulation up-regulates Heat Shock Factor 4 (CmHSFA4), a gene that is known to enhance chrysanthemum salt tolerance, and an ABA-SnRK2.2-ABF1/BRM signaling module that integrates phosphorylation-dependent protein stabilization and degradation with histone methylation dynamics to fine-tune salt stress–responsive gene expression in chrysanthemum is revealed.
Xinhui Wang, Han Wang, Hong-Yu Wei et al.· Science Advances· 0 citations
Abstract Although ERF transcription factors (TFs) play critical roles in abiotic stress tolerance, the molecular mechanisms underlying this role remain incompletely understood. This study identified BpERF1A in birch (Betula platyphylla) as a drought-responsive TF through co-expression regulatory network analysis. Expression of BpERF1A was stalwartly induced by drought stress, and drought treatment markedly boosted its promoter activity. Functional analyses demonstrated that overexpression of BpERF1A markedly improved drought tolerance compared with wild-type (WT) birch, whereas its repression increased drought sensitivity. Overexpression lines also exhibited higher antioxidant enzyme activities and proline content relative to WT. Chromatin immunoprecipitation-polymerase chain reaction, yeast one-hybrid and dual-luciferase (dual-LUC) assays confirmed that BpERF1A directly binds to G-box elements in the promoters of BpDHN (dehydrin) and BpAOS (allene oxide synthase), activating their transcription. Furthermore, overexpression of BpDHN/BpAOS enhanced drought tolerance and promoted reactive oxygen species (ROS) scavenging in transgenic plants. Protein–protein interaction analysis using bimolecular fluorescence complementation revealed that BpERF1A interacts with BpRAV1 to form a heterodimer, which further enhances BpERF1A binding to the BpDHN promoter and its transcriptional activation. Collectively, these findings establish a central role for the BpERF1A regulatory module in drought acclimation and highlight its synergistic interaction with BpRAV1, providing an effective strategy to enhance drought tolerance through improved ROS scavenging capacity.
Drought is a major environmental factor that affects Betula platyphylla (birch) survival and growth and even leads to death in severe cases. However, the genetic components underlying birch drought tolerance are largely unknown. Here, we identified and characterized a DREB gene (BpDRE1B) in birch, and overexpression of BpDRE1B improved the drought tolerance of transgenic birch. Through analysis of the previously reported drought regulatory network of birch, it was found that glutathione metabolism serves as a key pathway underlying BpDRE1B-mediated drought stress responses. Yeast one-hybrid (Y1H), electrophoretic mobility shift assay (EMSA), chromatin immunoprecipitation-qPCR (ChIP-qPCR), and dual-luciferase (dual-LUC) assays confirmed that BpDRE1B regulates the expression of BpGSTU8 by binding to its DRE element. Consistently, overexpression of BpGSTU8 (OE-BpGSTU8) was identified to increase the activity of glutathione-S-transferase to clear reactive oxygen species (ROS), thereby enhancing the drought resistance of birch. The protein interaction analysis revealed that BpDRE1B interacts with BpMAPK6, a kinase involved in stress signaling. Moreover, BpMAPK6-mediated phosphorylation of BpDRE1B enhanced its ability to activate BpGSTU8 expression. Collectively, our findings demonstrate that BpDRE1B positively regulates drought tolerance in birch by upregulating BpGSTU8, highlighting its crucial role in drought adaptation and providing a theoretical foundation for breeding drought-resistant birch varieties.
Wenshuo Gao, Zhicheng Zheng, Yingming Huang et al.· Journal of Experimental Bota...· 0 citations
The R1R2R3-MYB (3R-MYB) transcription factor subfamily is associated with stress tolerance; however, the underlying mechanisms in crops remain poorly understood. This study investigates the function of maize MYB3R in regulating seedling drought tolerance. We characterised MYB3R overexpression lines and CRISPR-Cas9 loss-of-function mutants in maize and rice using physiological assays and transcriptome profiling. DNA affinity purification sequencing (DAP-seq) and molecular interaction assays were employed to identify direct downstream targets. MYB3R overexpression enhanced drought tolerance by promoting root development, stomatal closure and antioxidant defence, whereas mutants displayed hypersensitivity. MYB3R binds the mitosis-specific activator (MSA) motif to directly transactivate the B-type cyclin gene CYCB1;2, and cycb1;2 mutants phenocopied the myb3r drought defects. These findings establish that the MYB3R-CYCB1;2 module positively regulates maize drought tolerance by coordinating developmental and physiological adaptations. This pathway provides a valuable molecular target for breeding drought-resilient crops.
Kang Guo, Yingli Jiang, Yuxin Guo et al.· The Plant Journal· 0 citations
The trehalose pathway primarily regulates flowering in plants through T6P (Trehalose-6-Phosphate) and TPS1 (TREHALOSE-6-PHOSPHATE SYNTHASE 1), although the specific regulatory mechanism remains uncertain. This study utilized full-length transcriptome and RNA-seq data to identify key genes responding to trehalose signal and impacting flowering in Magnolia liliiflora 'Hongyuanbao'. Analysis revealed 90, 438, 1,544, and 667 differentially expressed genes (DEGs) throughout the four flower bud differentiation stages (S1∼S4). GO and KEGG enrichment analyses indicated enrichment of DEGs from S1 to S4 in photoperiod and circadian rhythm pathways. Weighted gene co-expression network analysis (WGCNA) identified three significant co-expression modules, with significant correlations between the MEbrown and MEbrown modules. DEGs in the MEbrown module primarily participated in light response and carbon metabolism pathways, while DEGs in the MEblue module were primarily associated with stress response and sugar metabolism pathways. Additionally, protein-protein interaction (PPI) network analysis of flowering and sugar-related DEGs from both modules identified MlTPS1 as a central protein in the interaction network. Yeast two-hybrid (Y2H) analysis combined with bimolecular fluorescence complementation (BiFC) assays confirmed that MlTPS1 interacts with the flowering-promoting factor MlNFYC9 (NUCLEAR TRANSCRIPTION FACTOR Y SUBUNIT C-9) in the cytoplasm. Functional verification and expression analysis results indicated that MlNFYC9 significantly promotes the flowering process and exhibits prominent expression in the flower bud and early flower bud differentiation stages. This study elucidated the molecular mechanism by which 'Hongyuanbao' augments reproductive development under trehalose signal, providing a theoretical basis for refining flowering time regulation in Magnolia species.
Zan Chen, Xiaojun Chen, Feng Tian et al.· Plant physiology and biochem...· 0 citations
Exogenous spraying of CuB can alleviate the low-temperature stress injury of melon and tomato seedlings and is explored a new way to alleviate the abiotic stress injury of seedlings, which is of great significance for the early seedling development of oriental melons.
Yushan Huang, Haoxiong Tang, Fei Luo et al.· Plant, Cell and Environment· 0 citations
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