NOL‐mediated functional stay‐green traits in perennial ryegrass (Lolium perenne L.) involving multifaceted molecular factors and metabolic pathways regulating leaf senescence

Abstract

Loss of chlorophyll (Chl) is a hallmark of leaf senescence, which may be regulated by Chl catabolic genes, including NON‐YELLOW COLORING 1 (NYC1)‐like gene (NOL). The objective of this study was to determine molecular factors and metabolic pathways underlying NOL‐regulation of leaf senescence in perennial grass species. LpNOL was cloned from perennial ryegrass (Lolium perenne L) and found to be highly expressed in senescent leaves. Transient over‐expression of LpNOL accelerated leaf senescence and Chl b degradation in Nicotiana benthamiana. RNA‐interfering LpNOL in perennial ryegrass (NOLi) not only significantly blocked Chl degradation in senescent leaves, but delayed initiation and progression of leaf senescence. This study found in addition to functioning as a Chl b reductase, NOL could enact the functional stay‐green phenotype in perennial grass species, as manifested by increased photosynthetic activities in NOLi plants. Comparative transcriptomic analysis revealed that NOL‐mediated functional stay‐green in perennial ryegrass was mainly through the modulation of Chl catabolism, light harvesting of photosynthesis, photorespiration, cytochrome respiration, carbohydrate catabolism, oxidative detoxification, and abscisic acid biosynthesis and signaling pathways.