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.

PpTCP18 is upregulated by lncRNA5 and controls branch number in peach (Prunus persica) through positive feedback regulation of strigolactone biosynthesis

Branch number is an important agronomic trait in peach(Prunus persica)trees because plant architecture affects fruit yield and quality.Although breeders can select varieties with different tree architecture,the biological mechanisms underlying architecture remain largely unclear.In this study,a pillar peach(‘Zhaoshouhong’)and a standard peach(‘Okubo’)were compared.‘Zhaoshouhong’was found to have significantly fewer secondary branches than‘Okubo’.Treatment with the synthetic strigolactone(SL)GR24 decreased branch number.Transcriptome analysis indicated that PpTCP18(a homologous gene of Arabidopsis thaliana BRC1)expression was negatively correlated with strigolactone synthesis gene expression,indicating that PpTCP18 may play an important role in peach branching.Yeast one-hybrid,electrophoretic mobility shift,dual-luciferase assays and PpTCP18-knockdown in peach leaf buds indicated that PpTCP18 could increase expression of PpLBO1,PpMAX1,and PpMAX4.Furthermore,transgenic Arabidopsis plants overexpressing PpTCP18 clearly exhibited reduced primary rosette-leaf branches.Moreover,lncRNA sequencing and transient expression analysis revealed that lncRNA5 targeted PpTCP18,significantly increasing PpTCP18 expression.These results provide insights into the mRNA and lncRNA network in the peach SL signaling pathway and indicate that PpTCP18,a transcription factor downstream of SL signaling,is involved in positive feedback regulation of SL biosynthesis.This role of PpTCP18 may represent a novel mechanism in peach branching regulation.Our study improves current understanding of the mechanisms underlying peach branching and provides theoretical support for genetic improvement of peach tree architecture.

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.