Aug 2026· Frontiers in Plant Science· Vol 17· 0 citations· 75 references
Medicine
TL;DR
It is shown that methyl jasmonate (MeJA) substantially induces HY5 protein accumulation in a FIN219/JAR1-dependent manner, and a regulatory mechanism in which HY5 fine-tunes JA signaling and seedling development by integrating light and hormone cues is uncovered.
Abstract
Light is a key environmental signal that regulates plant growth and development. ELONGATED HYPOCOTYL 5 (HY5), a bZIP transcription factor, is a central positive regulator of photomorphogenesis in Arabidopsis thaliana, integrating light and hormone signaling pathways. However, the molecular role of HY5 in jasmonate (JA) signaling remains unclear. Here, we show that methyl jasmonate (MeJA) substantially induces HY5 protein accumulation in a FIN219/JAR1-dependent manner. Genetic evidence indicates that HY5 and FIN219 act synergistically to inhibit hypocotyl growth and coordinate defense-related transcriptional networks. Loss of HY5 function results in hypersensitivity to MeJA-mediated inhibition of hypocotyl elongation, and transcriptomic analyses reveal disturbances in numerous light- and JA-responsive genes. HY5 represses JAZ1 expression by binding to its G-box-containing promoter and physically interacts with JAZ1, suggesting both transcriptional and post-translational regulation. Furthermore, HY5 and MYC2 compete for binding at the JAZ1 promoter, modulating JA responses under far-red light. Together, our findings uncover a regulatory mechanism in which HY5 fine-tunes JA signaling and seedling development by integrating light and hormone cues. This work provides new insights into HY5-mediated crosstalk and identifies potential targets to improve stress resilience in crops.
The RNA polymerase II C-terminal domain (CTD) phosphatase CPL1/FRY2 is a multifunctional regulator involved in diverse stress responses, yet its role in orchestrating hormone-mediated immunity remains poorly understood. Here, we demonstrate that CPL1 regulates ABA biosynthesis and modulates SA/JA-associated defence responses in Arabidopsis thaliana. Loss of CPL1 function compromises resistance to the hemibiotrophic bacterial pathogen Pseudomonas syringae pv. tomato DC3000 (Pst DC3000), coinciding with suppressed SA signalling and ectopic activation of JA-, ethylene-, and abscisic acid (ABA)-responsive genes. Hormone profiling revealed that upon Pst DC3000 infection, cpl1 mutants specifically accumulated ABA, but not SA, JA, or ethylene. Epistasis analyses showed that this ABA accumulation stems from the derepression of the seed-specific transcription factor FUSCA3 (FUS3) in vegetative tissues, which in turn drives expression of the ABA biosynthetic gene NCED3. Chromatin immunoprecipitation analyses further revealed that FUS3 silencing in wild-type plants is maintained by repressive epigenetic marks, including low histone acetylation and high H3K9me2/3 levels, modifications that are disrupted in cpl1 mutants. Consequently, CPL1 promotes resistance to biotrophic/hemibiotrophic pathogens by epigenetically silencing FUS3 to prevent pathogen-induced ABA biosynthesis, thereby modulating SA/JA-associated defence responses. Our findings position CPL1 as a key integrator of epigenetic regulation, hormone crosstalk, and pathogen-specific immune tuning.
Lei He, Zhenjiang Wu, Ye Jin et al.· Plant, Cell and Environment· 0 citations
In canonical jasmonate (JA) signaling, MYC2 activity is restrained by JA-inducible JAZ repressors that are rapidly degraded upon JA perception. However, it remains unclear how MYC2 is attenuated during prolonged developmental processes such as leaf senescence, where sustained repression is required independently of acute JA fluctuations. Here, we identify C-type cyclin 1;1 (CycC1;1) as a negative regulator of JA-induced leaf senescence in Arabidopsis. CycC1;1 physically interacts with MYC2 in the nucleus to inhibit MYC2-mediated transcriptional activation of senescence-associated genes (SAGs) by interfering with RNA polymerase II recruitment. Additionally, CycC1;1 interacts with the Mediator subunit MED25 to disrupt its association with MYC2. Disruption of CycC1;1 accelerates JA-dependent leaf yellowing, whereas loss of MYC2 or MED25 fully suppresses this premature-senescence phenotype. Unlike JAZ repressors, CycC1;1 expression and protein stability are uncoupled from JA signaling. Phylogenetic analyses suggest that the CycC1;1-MYC2 interaction may predate the emergence of JAZ repressors in aquatic ancestors, and CycC1;1 shows evolutionarily conserved ability to interact with and inhibit MYC2 across different plant species. Collectively, our findings uncover a CycC1;1-MED25-MYC2-regulatory module wherein CycC1;1 suppresses MYC2 activity by inhibiting MED25 binding to MYC2 and RNA polymerase II recruitment, downregulating SAG expression and thus delaying leaf senescence in plants.
Cai-Yi Liao, Xiaolong Huang, Lin Li et al.· Journal of Integrative Plant...· 0 citations
Cold stress severely limits the yield and quality of fruit crops, yet its regulatory mechanisms in pitaya remain poorly understood. Here, we identified a cold-inducible bZIP transcription factor, HubZIP6, that plays a central role in enhancing cold tolerance in pitaya. HubZIP6 is a nuclear-localized protein with transcriptional activation activity, and its overexpression in Arabidopsis and tomato significantly improved cold tolerance, as reflected by higher survival rates, reduced ion leakage, and lower reactive oxygen species accumulation. Mechanistically, HubZIP6 directly binds to ACGT motifs in the promoters of HuCBF1 and HuCBF3, thereby activating their expression under cold stress. In addition, HubZIP6 physically interacts with the salicylic acid-binding protein HuSABP2, which synergistically enhances the transcriptional activation of HuCBF genes. Notably, HubZIP6 also directly activates HuSABP2, forming a regulatory loop that connects CBF transcriptional control with salicylic acid signaling. Consistently, overexpression of HuSABP2 further enhances cold tolerance in transgenic plants. Collectively, these findings demonstrate that cold tolerance is enhanced through HubZIP6-mediated integration of CBF activation and salicylic acid signaling, providing a promising genetic target for improving stress resilience in fruit crops.
Xinglong Hu, Irfan Ali Sabir, Ze-Liu Xu et al.· Molecular Horticulture· 0 citations
Abstract DELLA proteins are negative regulators of gibberellin (GA) signaling. Under GA-deficient conditions, DELLA accumulates in the nucleus and interacts with numerous transcription factors (TFs) via the GRAS domain. Recent studies have shown that DELLA interacts with TFs via the LHR1 subdomain and histone H2A via the PFYRE subdomain, respectively. It is essential for DELLA-mediated global transcription reprograming. DELLA exhibits strong transcriptional activity and acts as a co-activator of GAI-ASSOCIATED FACTOR1 (GAF1)/IDD2. The N-terminus of DELLA is necessary for strong transcriptional activity, but the regulatory activities and mechanisms of DELLA remain unclear. Therefore, we screened DELLA-interacting factors using the proximity biotinylation enzyme AirID and identified HISTONE ACETYLTRANSFERASE OF THE CBP FAMILY1 (HAC1). HAC1-mediated acetylation of histone H3 at the GAF1 target chromatin was necessary for transcriptional activation by the GAF1–DELLA complex. Additionally, the HAC1-mediated transcriptional activity of DELLA was involved in regulating plant growth. Moreover, ETHYLENE RESPONSE FACTOR2 (ERF2) was identified as a growth repressor gene regulated by the GAF1–DELLA–HAC1 complex. Here, we showed that DELLA proteins regulate plant growth via HAC1-mediated transcriptional regulation of ERF2.
Hiroki Ando, Akira Nozawa, Hidetaka Kosako et al.· The Plant Cell· 0 citations
This study establishes LF1 as a central hub coupling transcriptional and post-translational mechanisms to modulate BR-mediated leaf angle, providing targets for plant architecture improvement.
Jing You, Bingyu Ning, Yi Zhang et al.· The Plant Cell· 0 citations
Findings suggest that VvJAZ2 may function as a potential regulatory node, and support a working model of a dynamic "transcription-protein interaction" module to coordinate hormone signaling and metabolic reprogramming under cold stress.
Miao Shao, Lili Che, Shixiong Lu et al.· International Journal of Bio...· 0 citations
