CCCH protein-PvCCCH69 acted as a repressor for leaf senescence through suppressing ABA-signaling pathway

CCCH is a subfamily of zinc finger proteins involved in plant growth,development,and stresses response.The function of CCCH in regulating leaf senescence,especially its roles in abscisic acid(ABA)-mediated leaf senescence is largely unknown.The objective of this study was to determine functions and mechanisms of CCCH gene in regulating leaf senescence in switchgrass(Panicum virgatum).A CCCH gene,PvCCCH69(PvC3H69),was cloned from switchgrass.Overexpressing PvC3H69 in rice suppressed both natural senescence with leaf aging and dark-induced leaf senescence.Endogenous ABA content,ABA biosynthesis genes(NCED3,NCED5,and AAO3),and ABA signaling-related genes(SnRKs,ABI5,and ABF2/3/4)exhibited significantly lower levels in senescencing leaves of PvC3H69-OE plants than those in WT plants.PvC3H69-suppression of leaf senescence was associated with transcriptional upregulation of genes mainly involved in the light-dependent process of photosynthesis,including light-harvesting complex proteins,PSI proteins,and PSII proteins and downregulation of ABA biosynthesis and signaling genes and senescence-associated genes.PvC3H69 could act as a repressor for leaf senescence via upregulating photosynthetic proteins and repressing ABA synthesis and ABA signaling pathways.