Abstract
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. To genetically dissect the complex regulatory mechanism underlying leaf senescence, we identified an early leaf senescence mutant, rse1. RSE1 encodes a putative glycosyltransferase. Loss-of-function mutations in RSE1 resulted in precocious leaf yellowing and up-regulation of senescence marker genes, indicating enhanced leaf senescence. Transcriptome analysis revealed that salicylic acid (SA) and defense signaling cascades were up-regulated in rse1 prior to the onset of leaf senescence. We found that SA accumulation was significantly increased in rse1. The rse1 phenotypes are dependent on SA-INDUCTION DEFICIENT 2 (SID2), supporting a role of SA in accelerated leaf senescence in rse1. Furthermore, RSE1 protein was localized to the cell wall, implying a possible link between the cell wall and RSE1 function. Together, we show that RSE1 negatively modulates leaf senescence through an SID2-dependent SA signaling pathway.
Highlights
Senescence is the last stage of plant development and is a genetically programmed and evolutionarily advantageous process
We showed that RSE1 negatively regulates leaf senescence through an salicylic acid (SA)-dependent signaling pathway
Premature leaf senescence is enhanced in rse1 mutants, accompanying with the up-regulation of senescence marker genes
Summary
Senescence is the last stage of plant development and is a genetically programmed and evolutionarily advantageous process. Plant hormones play a crucial role in the regulation of senescence by integrating internal and external signals (Khan et al, 2014). Loss-of-function mutations in UGT76B1 glycosyltransferase (GT) that facilitates the glycosylation of isoleucic acid result in early leaf senescence accompanied with increased levels in SA and an up-regulation of defense-related genes and SAGs (von Saint Paul et al, 2011). Glycosylation is a crucial biological reaction in living organisms, but the physiological role of the majority of GTs remains largely unknown. This may be due to the functional redundancy in the large gene families, substrate diversity, and substrate specificity. Our results provide an insight into leaf senescence modulated by the crosstalk between glycosylation and SA signaling
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