Molecular Plant最新文献

Plastoglobules, lipoprotein particles associated with thylakoid membranes, serve as critical hubs for chloroplast acclimation to environmental perturbations. However, the molecular mechanisms underlying plastoglobuli-associated signal perception and transduction remain poorly understood. Here, we identify a redox-regulated kinase complex in Arabidopsis that mediates plastoglobules' response to red light. Two plastoglobule-localized kinases, ACTIVITY OF BC1 COMPLEX KINASE 1 and 3 (ABC1K1 and ABC1K3), form a dynamic hetero-oligomeric complex essential for maintaining plastoquinone (PQ) pool homeostasis and optimizing photosynthetic efficiency. These kinases dynamically adjust their conformational states in response to PQ redox-state changes induced by environmental light conditions. Under preferential photosystem II (PSII) excitation induced by red light, reduced PQ pool initiates a signaling cascade through activation of the thylakoid oxidoreductase LUMEN THIOL OXIDOREDUCTASE 1 (LTO1). Activated LTO1 then oxidizes ABC1K1 at Cys107, triggering its oligomerization via inter-molecular disulfide-bond formation. This oligomeric state change leads to enhanced interaction between ABC1K1 and ABC1K3 oligomers, reconfiguring the kinase complex to relieve ABC1K3-mediated inhibition of PQ mobilization. Consequently, by restoring PQ-pool homeostasis, the ABC1K1-ABC1K3 complex mitigates PSII photodamage and safeguards photosynthesis, thereby enabling chloroplast adaptation to red light. Taken together, our findings reveal a redox-regulation mechanism by which plastoglobules integrate environmental cues with chloroplast homeostasis, providing new insights into plastoglobule-mediated stress acclimation.

Gibberellin (GA) is a phytohormone that regulates key developmental processes in plants, including seed germination and photomorphogenesis. It is well established that GA signaling involves GA-triggered, 26S proteasome-dependent degradation of DELLA proteins. Whether DELLA proteins also undergo autophagic degradation to mediate GA signaling remains unclear. In this study, we investigated the responsiveness of Arabidopsis seedlings to GA and the dynamics of DELLA proteins under nutrient starvation in darkness. We found that GA-induced seed germination and skotomorphogenesis are impaired in autophagy mutants and that GA promotes the autophagic degradation of DELLA proteins. Biochemical and protein localization analyses revealed that GA promotes the nuclear export of DELLA proteins and ATG8, their co-localization in autophagosomes, and autophagosome formation. Further biochemical studies demonstrated that GA enhances the interaction between ATG8 and GID1, thereby promoting the association of ATG8 with DELLA proteins and their autophagic degradation. Through this mechanism, GA promotes seed germination and skotomorphogenesis under nutrient starvation in darkness, enabling seedlings to penetrate the soil rapidly, capture sunlight, and shift to autotrophic growth to overcome nutrient deficiency.

Plant receptor-like kinases (RLKs) often function as immune receptors for exogenous and endogenous elicitors. However, only a few immune ligand-receptor pairs have been identified in rice. In this study, we report that a rice gene encoding the secretory immunopeptide OsIMP1 is induced by pathogen-associated molecular patterns. The OsIMP1 peptide triggers immune responses and positively regulates rice disease resistance. Furthermore, the leucine-rich repeat receptor-like kinases OsRLK5 and OsRLK5-L and the somatic embryogenesis receptor-like kinase 2 (OsSERK2) are essential for OsIMP1-triggered immunity. OsRLK5 interacts with and phosphorylates OsSERK2. OsIMP1 directly binds to the extracellular domain of OsRLK5, positively regulating pattern-triggered immunity. Notably, overexpression of OsRLK5 confers increased resistance to bacterial and fungal diseases without a yield penalty in rice. Taken together, these results indicate that OsIMP1 and OsRLK5/OsRLK5-L form ligand-receptor pairs that confer rice resistance to multiple pathogens without incurring a growth penalty, providing important targets for developing rice varieties with broad-spectrum disease resistance.

Shoot branching, an important agronomic trait, is environmentally and developmentally regulated. Epigenetic modifications play a pivotal role in regulating transcriptional responses to light and temperature cues that control plant growth. Nevertheless, the roles of epigenetic modifiers in regulating shoot branching under varying temperatures remain elusive. In this study, we reveal that elevated temperature suppresses lateral bud outgrowth in tomato (Solanum lycopersicum), accompanied by increased HISTONE DEACETYLASE 4 (HDA4) levels. Loss of function of SlHDA4 augments lateral bud outgrowth, resulting from a reduced auxin response. Notably, increased lateral bud outgrowth observed in slhda4 mutants is insensitive to elevated temperature but can be restored by SlHDA4 overexpression. Furthermore, we found that the histone deacetylase SlHDA4 interacts with the transcription factor SlTCP15 to suppress the expression of genes encoding the light receptor SlPHYB1 and auxin signaling repressor SlIAA12 by decreasing the H3K9ac levels at their promoters. In summary, our work demonstrates that the SlTCP15-SlHDA4 module participates in the regulation of lateral bud outgrowth at warm temperatures by enhancing auxin biosynthesis and signaling in tomato.