Arabidopsis STAYGREEN-LIKE (SGRL) promotes abiotic stress-induced leaf yellowing during vegetative growth

During leaf senescence in Arabidopsis, STAYGREEN 1 (SGR1) and SGR2 regulate chlorophyll degradation positively and negatively, respectively. SGR-LIKE (SGRL) is also expressed in pre-senescing leaves, but its function remains largely unknown. Here we show that under abiotic stress, Arabidopsis plants overexpressing SGRL exhibit early leaf yellowing and sgrl-1 mutants exhibit persistent green color of leaves. Under salt stress, SGR1 and SGRL act synergistically for rapid Chl degradation prior to senescence. Furthermore, SGRL forms homo- and heterodimers with SGR1 and SGR2 in vivo, and interacts with LHCII and chlorophyll catabolic enzymes. The role of SGRL under abiotic stress is discussed.