Effects Of Heat And Low Temperature Conditioning Treatment On Postharvest Storage And HSPs Gene Expression Of Wampee Fruits

Wampee(Clausena lansium(Lour.)Skeels)is a genus of Rutaceae,which is a kind of non-climacteric fruit with soft and juicy flesh and thin skin.It is easy to suffer from mechanical damage,Browning or rot in the post-harvest process,and its quality deteriorates rapidly.Wampee fruit will lose its commercial value after 2-3d.Therefore,the research on storage,transportation and preservation technology of wampee fruits after harvest is of great significance to the sustainable development of yellow peel industry.In this study,'Dajixin'wampee was used as the experimental material and the effect of heat treatment(HT)and low temperature conditioning(LTC),to investigate the response mechanism of heat shock protein gene to postharvest browning and its correlation with fruit quality deterioration were studied.The results of the study are as follows:1.The effects of heat treatment(HT)and low temperature conditioning(LTC)on the storage quality and postharvest physiology of the 'Dajixin' wampee fruits were studied.The wampee fruit were treated with heat treatment(50 ?,30 s)?LTC ?(12?,4 d)?LTC ?(8?,4 d)and LTC ?(12?,2 d to 8?,2 d)and then stored at 3±0.5? to investigate the effects on storage quality and postharvest physiology.The results showed that compared with the control,low temperature conditioning treatment delays the browning of the wampee fruits,improved total soluble solids(TSS)and vitamin C content,and inhibited the accumulation of malondialdehyde(MDA)content,maintained higher activities of superoxide dismutase(SOD)and phenylalanine ammonia lyase(PAL)activity,and lower activities of peroxidase(POD)and polyphenol oxidase(PPO)activity.Moreover,the high total phenol content and antioxidat activity were maintained.Moreover,maintained a high total phenolic and flavonoid content.Thereby delayed the senescence of the wampee fruits post-harvest,it is beneficial to reduce the browning of the wampee fruits and improve the storage quality.In conclusion,LTC ? treatment was the best,followed by HT and LTC ? treatment,LTC ? was the worst.2.The HSPs gene family members related to browning of wampee were screened.The effects of heat treatment(HT)and low temperature conditioning(LTC)(LTC ?)of the 'Dajixin' wampee fruits were studied.Transcriptome sequencing was performed using CK,HT and LTC samples at day 0 and day 6.29 ClHSP70 and 38 ClsHSP differentially expressed genes were screened from the wampee RNA-Seq database,and their gene expressions had different responses to HT and LTC.After NCBI Blast alignment and differential sequence analysis,10 CIHSP70 and 6 ClsHSP genes responding to HT and LTC ? were screened for gene expression verification..3.Members of the HSP gene family involved in postharvest browning were identified.10 HSP70 and 6 sHSP genes were obtained by RNA-Seq database and sequence analysis of wampee,respectively named CIHSP70-1-10 and ClsHSP1-6.The phylogenetic tree analysis showed that the 10 CIHSP70 and 6 ClsHSP belong to different subgroups,in which ClHSP70-1/5 and EjHSP70-1 are in the same group,CIHSP70-7 and AtHSP70-5 are in the same group,CIHSP70-6 and AtHSP70-11/12 are in the same group,CIHSP70-8 and AtHSP70-6/7 are in the same group,CIHSP70-9 and AtHSP70-9/10 are in the same group.CLHSP70-2/3/4/10 has low homology with other groups.ClsHSP2 and EjsHSP4 were in the same group,while ClsHSP6 and EjsHSP6 were in the same group.At the transcriptional level,CIHSP70 and ClsHSP genes showed different response patterns to HT and LTC treatment.In addition to CIHSP70-2 and CIHSP70-7,the expressions of the other 8 CIHSP70 and ClsHSP1/3/4/5/6 genes were up-regulated by LTC treatment,which was negatively correlated with fruit browning,indicating that LTC participated in post-harvest browning of wampee fruits by regulating these HSP genes.CIHSP70-2/3/7/9 and ClsHSP1/2/6 were continuously induced by HT during post-harvest storage,showing a negative correlation with the browning index,indicating that HT was involved in the post-harvest browning regulation of wampee fruits by regulating these HSP genes.In this paper,the study found that HT and LTC treatment can effectively delay the wampee fruit postharvest browning,further study found that 10 CIHSP70 and 6 ClsHSP gene family members were involved in the browning of wampee fruits,two classes of genes involved in wampee fruit browning mechanism of each are not identical,HT may reduce browning by regulating CIHSP70-2/3/7/9 and ClsHSP 1/2/6 genes.LTC may reduce browning by regulating CIHSP70 and ClsHSP 1/3/4/5/6 genes.The effect of LTC treatment on browning was better than that of HT treatment.According to the correlation between fruit browning index,PPO enzyme activity and HSP gene expression,CIHSP70-4/5/6/8/10 and ClsHSP3/4/5/6 may be important genes in response to wampee browning.