Effect of bagging on expression of crucial structural genes of anthocyanin biosynthesis in ‘Tianyuanhong'kiwifruit based on RNA-seq

LI Yukuo; FANG Jinbao; LIN Miaomiao; LI Zhi; SUN Shihang; QI Xiujuan

doi:10.13925/j.cnki.gsxb.20170127

Abstract：[Objective]The aim of this survey is to explore the effect of bagging on expression of crucial structural genes of anthocyanin biosynthesis of different parts of kiwifruit fruits in different stages of growth and development and provide evidence for the impacts of illumination on anthocyanin synthesis.[Methods] Full red-flesh fruits of kiwifruit ‘Tianyuanhong'were selected as materials for bagging treatments.According to the RNA-seq,12 differential expression genes (DEGs) were screened.These 12 selected DEGs were conducted to analysis on the expression rule in the seven stages using quantitative realtime poIymerase chain reaction (qRT-PCR).Finally,the crucial candidate genes were confirmed based the results of qRT-PCR and cluster analysis.And then the relative quantitative analysis of expression level of the crucial candidate genes in different treatments,different periods and different parts of fruits was conducted by the qRT-PCR,and furthermore,the correlation analysis between expressions of genes and anthocyanin contents was also conducted.[Results]The expressions of 12 structural genes presented regular change rules although their expressions were different.The expression levels of F3H,LDOX and F3GT 110 days after full bloom (DAFB) when the flesh turned to be red were higher than those in other stages.The results of cluster analysis showed that LDOX and F3GT were respectively clustered into one class and were obviously separated from other genes.The expression level of LDOX of epicarp of treatment 1 displayed an increase trend and reached peak on 110 d during the growth and development of fruits.While the levels of LDOX of epicarp of treatment 2 and treatment 3 were lower than that of treatment 1,especially on 100 d and 110 d.This indicated that bagging treatment and bagging-debagging treatment could decrease the expression level of LDOX in epicarp when the flesh turned to be red.The changing rule of LDOX expression level of sarcocarp of treatment 1 was similar to the trend of epicarp.As the developing of fruit,the expression level of LDOX increased and reached its maximum value on 110 d and it was evidently higher than those in other stages.While the expression level of expression LDOX of treatment 2 and treatment 3 was obviously lower than that of treatment 1.This phenomenon suggested that bagging treatment and bagging-debagging treatment could decrease the expression level of LDOX in sarcocarp.There was no obvious changing rule for the expression of LDOX of columella of treatment 1 and treatment 2.However,the expression level of LDOX of treatment 3 was higher than that of treatment 1 and treatment 2 on 110 d,which hinted that bagging treatment promoted the expression of LDOX in columella.The expression level of F3GT in epicarp of treatment 1,treatment 2 and treatment 3 displayed a similar changing rule during the period of growth and development of fruit.The expression level of F3GT increased from 90 d to 110 d,but the expression level of F3GT of treatment 1 was higher than that of treatment 2 and treatment 3,especially on 110 d.And the expression level of F3GT of treatment 2 was higher than that of treatment 3.These phenomenon indicated that bagging-debagging treatment could increase the level of F3GT in epicarp.The expression level of F3GT in sarcocarp of treatment 1 displayed an increase trend and reached peak on 100 d,which was the same as the expression level of LDOX in sarsocarp.The expressing of F3GT in columella of treatment 1,treatment 2 and treatment 3 had no obvious rule.The expression level of LDOX in sarcocarp of treatment 1 and treatment 2 and the expression level of LDOX in columella of treatment 3 had a very significant correlation with anthocyanin content.And the correlation between expression level of LDOX in epicarp and sarcocarp of treatment 3 and anthocyanin content was statistically significant.The expression level of F3GT in sarcocarp of treatment 1 and the expression level of LDOX in columella of treatment 3 had a very significant correlation with anthocyanin content.And the correlation between expression level of LDOX in epicarp of treatment 3 and the expression level of LDOX in sarcocarp of treatment 2 and anthocyanin content were also statistically significant.[Conclusion] LDOX and F3GT might be the crucial structural genes of anthocyanin biosynthesis in the fruits of ‘Tianyuanhong'kiwifruit.Bagging treatment inhabited the expression of LDOX in epicarp and sarcocarp,while it promoted the expression of LDOX in columella.Bagging-debagging treatment promoted the expression of F3GT in epicarp while it suppressed the expression of F3GT in sarsocarp,which was consistent with the expression rule of LDOX in sarcocarp.Bagging treatment had no obvious impact on expression of F3GT in columella.