热空气处理对靖安椪柑幼果柠檬酸代谢的影响

Effects of Hot Air Treatment on Citric Acid Metabolism In Jing'an Ponkan Fruitlet

为探究柑橘果实柠檬酸的降解机制,以盛花后120 d的靖安椪柑果实为材料,研究了40℃热空气处理48 h对椪柑果实有机酸含量变化及柠檬酸代谢相关基因表达的影响。结果表明:靖安椪柑幼果有机酸以柠檬酸为主,热处理能显著促进果实柠檬酸含量的下降。同时,热处理诱导CitCS1和CitCS2基因表达上调,其中CitCS1表达与对照达显著性差异水平;热处理后CitAcos基因家族成员表达量均得到促进,CitIDH2被短暂诱导表达,热处理对CitIDH3基因表达也有促进作用;热处理还能显著促进CitGAD4和CitGAD5两个基因表达,但对CitGS基因表达无显著性影响。以上结果说明,热空气处理能促进靖安椪柑幼果中柠檬酸的降解,使果实有机酸含量下降,这种变化和柠檬酸代谢相关基因表达密切相关,其中CitAcos、CitIDH1/3和CitGAD4基因表达上调可能是导致果实有机酸下降的主要原因。

To explore the decomposition mechanism of citric acid in citrus fruit,Jing’an ponkan fruitlet were used to investigate the effects of hot air(40℃,48 h)treatment(HAT)on organic acid content and citric acid metabolism-related gene expression.The results showed that citric acid was the main organic acid in Jing’an ponkan fruitlet,and decreased significantly faster in HAT fruits than in the control.Meanwhile HAT could induce the expression of CitCS1 and CitCS2,which had significantly different levels in CitCS1 expressions.The expression levels of CitAcos were also promoted by HAT.HAT could induce temporary CitIDH2 expression and promoted the expression of CitIDH3.In addition,HAT also significantly up-regulated CitGAD4 and CitGAD5 expression,but had no significant effect on CitGS.These results suggested that HAT could promote the degradation of citric acid in Jing’an ponkan fruitlet,then the organic acid contents decreased,which was guided by the changes of citric acid metabolism-related gene expression,and the up-regulation of CitAco1,CitIDH1,CitIDH3 and CitGAD4 expression maybe the major cause of organic acid decline in Jing’an ponkan fruit during maturation.