The Stay-Green Rice like (SGRL) gene regulates chlorophyll degradation in rice

Abstract

The Stay-Green Rice (SGR) protein is encoded by the SGR gene and has been shown to affect chlorophyll (Chl) degradation during natural and dark-induced leaf senescence. An SGR homologue, SGR-like (SGRL), has been detected in many plant species. We show that SGRL is primarily expressed in green tissues, and is significantly downregulated in rice leaves undergoing natural and dark-induced senescence. As the light intensity increases during the natural photoperiod, the intensity of SGRL expression declines while that of SGR expression increases. Overexpression of SGRL reduces the levels of Chl and Chl-binding proteins in leaves, and accelerates their degradation in dark-induced senescence leaves in rice. Our results suggest that the SGRL protein is also involved in Chl degradation. The relationship between SGRL and SGR and their effects on the degradation of the light-harvesting Chl a/b-binding protein are also discussed.

Keywords: CCE; Chl; Chl catabolic enzyme; Chl catabolite reductase; Chlorophyll degradation; LHCI; LHCII; LHCP; Leaf senescence; Light-harvesting chlorophyll a/b-binding protein (LHCP); MCS; NOL; NYC1; PAO; PPH; RCCR; Rice (Oryza sativa L.); SGR; SGRL; Stay-Green Rice; Stay-Green Rice like; Stay-Green Rice like (SGRL); chlorophyll; light-harvesting chlorophyll a/b-binding protein; light-harvesting chlorophyll a/b-binding protein complex of photosystem I; light-harvesting chlorophyll a/b-binding protein complex of photosystem II; metal chelating substance; non-yellow coloring1; non-yellow coloring1 like; pFCC; pheophorbide a oxygenase; pheophytinase; primary fluorescent chlorophyll catabolite.