PpERF3 positively regulates ABA biosynthesis by activating PpNCED2/3 transcription during fruit ripening in peach

The plant hormone ethylene regulates ripening in climacteric fruits.The phytohormone abscisic acid(ABA)affects ethylene biosynthesis,but whether ethylene influences ABA biosynthesis is unknown.To explore this possibility,we investigated the interactions between the ABA biosynthesis genes PpNCED2/3 and the ethylene response transcription factor PpERF3 in peach fruit.The ABA content increased during fruit maturation and reached a peak at stage S4 III.The increase was greatly inhibited by the ethylene inhibitor 1-MCP,which also suppressed PpERF3 expression.PpERF3 shared a similar expression profile with PpNCED2/3,encoding a rate-limiting enzyme involved in ABA biosynthesis,during fruit ripening.A yeast one-hybrid assay suggested that the nuclear-localized PpERF3 might bind to the promoters of PpNCED2/3.PpERF3 increased the expression of PpNCED2/3 as shown by dual-luciferase reporters,promoter-GUS assays and transient expression analyses in peach fruit.Collectively,these results suggest that ethylene promotes ABA biosynthesis through PpERF3’s regulation of the expression of ABA biosynthesis genes PpNCED2/3.

Application of an antibody chip for screening differentially expressed proteins during peach ripening and identification of a metabolon in the SAM cycle to generate a peach ethylene biosynthesis model

Peach(Prunus persica)is a typical climacteric fruit that produces ethylene rapidly during ripening,and its fruit softens quickly.Stony hard peach cultivars,however,do not produce large amounts of ethylene,and the fruit remains firm until fully ripe,thus differing from melting flesh peach cultivars.To identify the key proteins involved in peach fruit ripening,an antibody-based proteomic analysis was conducted.A mega-monoclonal antibody(mAb)library was generated and arrayed on a chip(mAbArray)at a high density,covering~4950 different proteins of peach.Through the screening of peach fruit proteins with the mAbArray chip,differentially expressed proteins recognized by 1587 mAbs were identified,and 33 corresponding antigens were ultimately identified by immunoprecipitation and mass spectrometry.These proteins included not only important enzymes involved in ethylene biosynthesis,such as ACO1,SAHH,SAMS,and MetE,but also novel factors such as NUDT2.Furthermore,protein–protein interaction analysis identified a metabolon containing SAHH and MetE.By combining the antibody-based proteomic data with the transcriptomic and metabolic data,a mathematical model of ethylene biosynthesis in peach was constructed.Simulation results showed that MetE is an important regulator during peach ripening,partially through interaction with SAHH.