The MsZFP1-MsWRKY40-MsWRKY41 module efficiently regulates LHCII biogenesis via ABA-dependent manner in alfalfa.

Abstract

The light-harvesting complex (LHC) is the antenna system of photosystem that affects the photosynthetic efficiency of plants. In this study, MsWRKY41 was demonstrated to directly activate the expression of <i>MsAlb3</i> and <i>MsDVR1</i>, which involved in LHC protein insertion into thylakoid membrane and chlorophyll biosynthesis, respectively. Knockdown of <i>MsWRKY41</i> in alfalfa led to yellow-green leaves and abnormal thylakoid structure. <i>MsWRKY41</i> was the downstream target gene of MsWRKY40, which also directly and positively regulated the expression of four LHC protein genes <i>MsLHCB1/4.3/5/7</i>. Overexpression of <i>MsWRKY40</i> increased the accumulation of PSII-LHCII supercomplexes. MsWRKY40 physically interacted with zinc finger protein MsZFP1, which partly inhibited the expression of MsWRKY40-targeted genes. This interaction was weakened by physiologically high levels of ABA, leading to up-regulated expression of MsWRKY40-targeted genes. These results revealed a regulatory module centered on MsWRKY40-MsWRKY41, which integrates the biosynthetic processes of LHCB subunits and chlorophyll into a gene regulatory network, efficiently regulating LHCII biogenesis.