猕猴桃PG基因在果实贮藏过程中的表达及其与硬度的关系

Relationship Between PG Gene Expression and Fruit Firmness During Kiwifruit Storage

为鉴定猕猴桃果实贮藏过程中参与果胶降解的关键酶多聚半乳糖醛酸酶(PG)基因,以‘徐香’猕猴桃为试材,利用转录组测序(RNA-seq)和实时荧光定量(q RT-PCR)技术,研究了猕猴桃PG基因在不同成熟进程及外源乙烯诱导后果实中的表达变化。根据RNA-seq结果,可以将37个PG基因在采后不同时期的表达趋势分为4类,Achn325011、Achn240441、Achn071601和Achn100411,分别在采后2、4、6和8 d有表达高峰。鉴于果实硬度在常温贮藏6 d较4 d时急剧下降,因此利用q RT-PCR重点验证了其中的2类14个基因,发现4个基因在采后2 d和4 d明显上调,与果实硬度在6 d时的下降相关。进一步利用外源乙烯处理果实,发现其中1个基因Achn071601在处理与对照果实中的差异表达与同时期果实硬度的变化趋势一致,是猕猴桃关键的PG基因。

RNA-sequence and real-time quantitative polymerase chain reaction（PCR）technique（q RT-PCR）were used to identify the expression of key polygalacturonase（PG）genes involved in pectin degradation in kiwifruit,stored at room temperature at different time periods during storage. The expression pattern of 37 PG genes could be divided into 4 groups according to the RNA-sequence results of different samples stored at room temperature. For example,Achn325011,Achn240441,Achn071601 and Achn100411 genes present a peak expression at 2,4,6 and 8 days after harvest. Fourteen PG genes belonging to groups 1 and 4 were verified using the q RT-PCR as a decrease in fruit firmness on the 6 d after storage was observed. Among these PG genes,the expression of 4 genes was related to the fruit firmness change. Moreover,the expression of these 4 genes was also evaluated in kiwifruits treated with exogenous ethylene. The results of ethylene treatment showed that the expression of a single gene called Achn071601 was consistent with the fruit firmness change during the storage period. Therefore,Achn071601 should be considered as a key PG gene in kiwifruit.