Glycosyltransferase-like RSE1 negatively regulates leaf senescence by modulating salicylic acid signaling in Arabidopsis

Leaf senescence is a developmental process designed for nutrient recycling and relocation to maximize growth competence and reproductive capacity of plants. Thus, plants integrate developmental and environmental signals to precisely control senescence. However, it remains largely elusive as to how plants coordinate genetic, epigenetic, and metabolic pathways for the regulation of senescence. To genetically dissect the complex regulatory mechanism underlying leaf senescence, we identified an early leaf senescence mutant, rse1. RSE1 encodes a putative glycosyltranferase. Loss-of-function mutations in RSE1 resulted in precocious leaf yellowing and up-regulation of senescence maker genes, indicating enhanced leaf senescence. Transcriptome analysis revealed that salicylic acid (SA) and defense signaling cascades were activated in rse1 prior to the onset of leaf senescence. In agreement with the phenotypes, we found that SA accumulation was significantly increased in rse1. We also discovered that the rse1 phenotypes are dependent on SA-INDUCTION DEFICIENT 2 (SID2), indicating a role of SA in accelerated leaf senescence in rse1. Furthermore, RSE1 protein was localized to the cell walls, and rse1 displayed increased glucose contents in the cell walls, implying a possible link between the cell walls and RSE1 function. Together, we show that RSE1 negatively modulate leaf senescence through an SID2-dependent SA signaling pathway.