Candidate Gene Discovery Of Peach Flower Bud With Cold Resistance Based On Tran-scriptomics

Peach(Prunus persica L.)is native to China.In recent years,with the frequent occurrence of extreme weather,extreme low temperature in winter has a great impact on open cultivation of peach.In this study,dormant flower buds of peach cultivar’Shijizhixing’ with strong cold resistance and peach cultivar ’21shiji’ with weak cold resistance were used as experimental materials to determine the relationship between many important biochemical substances and cold resistance of peach buds under natural overwintering conditions.At present,there has been no repor t on the regulation of ethylene on cold resistance of peach.This study focused on the determination of ethylene release rate in ’Shijizhixing’ and ’21shiji’ dormant flower buds under low temperature stress,and conducted transcriptomics determination and candidate gene mining of flower buds in different treatment periods.It provides an important theoretical reference for the future study on the mechanism of ethylene in peach flower buds cold resistance.The results are as follows:(1)Under natural overwintering conditions,the contents of soluble sugar(SS),soluble protein(SP),malondialdehyde(MDA),superoxide dismutase(SOD)and peroxidase(POD)in different stages of ’Shijizhixing’ and ’21shiji’ dormant flower buds were determined;at the same time,the ethylene release rate was measured at low temperature(4℃)for 0h,12 h,24h,48 h and 72 h.The results showed that MDA,SOD and POD were significantly different between the two peach cultivars.SOD and POD were positively correlated with the cold resistance of peach flower buds,MDA was negatively correlated with the cold resistance of peach flower buds,and SS and SP were not significant correlated with the cold resistance of peach flower buds.The ethylene release rate of ’Shijizhixing’ peach flower buds was significantly higher than’21shiji’.(2)The flower buds of ’Shijizhixing’ peach and ’21shiji’ peach treated at low temperature(4℃)for 12 h,24h and 48 h were used as test materials for transcriptome sequencing.A total of 1817 differentially expressed genes were screened,including768 up-regulated and 1049 down-regulated differentially expressed genes.There were10 differentially expressed transcription factors related to cold resistance,which mainly existed in the ERF,bHLH and MYB families.(3)Through transcriptomics screening and qRT-PCR analysis,a structural gene PpACO1 involved in ethylene synthesis and a transcription factor PpERF012 were screened out.It is preliminarily concluded that the interaction between PpERF012 and PpACO1 genes plays an important role in cold resistance of peach flower buds.