中华猕猴桃(Actinidiachinensis Planch)果实香气成分及相关基因表达

Volatile components and their corresponding synthetic gene expression profile in the fruits of Actinidia chinensis

为了解中华猕猴桃（Actinidia chinensis Planch）不同品种果实挥发性香气成分差异及其相关生物合成基因的表达模式，采用顶空-固相微萃取结合气相色谱-质谱仪（Head Space-Solid Phase Micro Extraction/Gas Chromatography-Mass Spectrometry，HS-SPME/GC-MS）方法，分析6个品种（‘翠玉’、‘金桃’、‘金艳’、‘楚红’、‘东红’、‘西选2号’）成熟果实的挥发性香气成分组成，并通过实时定量PCR（RT-qPCR）检测醇酰基转移酶基因（AcATs16）、脂氧合酶基因（AcLox2）和萜烯合酶基因（AcTPS1）在果实后熟过程中的表达量动态变化. 在6个检测猕猴桃品种中共鉴定了92种香气化合物. ‘翠玉’、‘金桃’、‘金艳’、‘楚红’、‘东红’、‘西选2号’猕猴桃品种分别有35、32、30、44、28、17种香气成分. ‘翠玉’、‘金桃’和‘金艳’中香气成分主要是酯类化合物，‘楚红’和‘东红’的香气成分分别以醛类和萜类为主，而‘西选二号’的香气成分由醛类和萜类组成. 随着猕猴桃果实的成熟度增加，AcATs16和AcLox2的表达量先增加后降低. AcATs16的表达量在‘翠玉’、‘金艳’中显著高于其他品种，而在‘翠玉’和‘楚红’中AcLox2的表达量显著高于其他品种. AcTPS1的表达量在‘金桃’、‘东红’、‘西选2号’果实后熟过程中逐渐升高，但在‘翠玉’、‘金艳’、‘楚红’中未见表达. 本研究表明猕猴桃果实中挥发性化合物种类和相对含量不同导致了香气的差异；AcATs16、AcLox2和AcTPS1在猕猴桃后熟过程中的差异表达与香气成分的合成密切相关；结果可为猕猴桃品种识别、果实质量评价和分子辅助育种提供依据. （图1 表4 参38）

This study aimed to identify the difference in volatile aromatic components and the relationship with the expression pattern of their corresponding bio-synthesis genes in six kiwifruit （Actinidia chinensis） varieties （Cuiyu, Jintao, Jinyan, Chuhong, Donghong, and Xixuan）. To provide a foundation for kiwifruit variety recognition, fruit quality evaluation, and molecular-assisted breeding, the volatile aromatic components in the ripe fruits of six kiwifruit varieties were evaluated by head space-solid phase micro extraction/gas chromatography-mass spectrometry. The aroma-synthesis-related genes, including acyltransferases （AcAT16）, lipoxygenase （AcLox2）, and terpene synthase genes （AcTPS1）, were detected by the real time-quantitative polymerase chain reaction （qPCR） during the postharvest stage of fruits. Ninety-two aroma chemicals were identified in the tested kiwifruit cultivars. There were 35, 32, 30, 44, 28, and 17 of aromatic compounds in Cuiyu, Jintao, Jinyan, Chuhong, Donghong, and Xixuan, respectively. Esters were the main aroma components in Cuiyu, Jintao, and Jinyan. The major aromatic compounds of Chuhong, Donghong, and Xixuan were aldehydes and terpenoids. The expression level of AcATs16 and AcLox2 increased, and then decreased during the ripening of kiwifruit fruits. The expression of AcATs16 was significantly higher in Cuiyu and Jinyan than in other varieties. AcLox2 indicated significant abundance in Cuiyu and Chuhong. AcTPS1 was up-regulated in Jintao, Donghong, and Xixuan with fruit ripening; however, this was not observed in Cuiyu, Chuhong, and Jinyan. The difference in the composition and content of volatile aromatic components contributes to the difference in aroma in different kiwifruit cultivars. The diverse expression of AcATs16, AcLox2, and AcTPS1 might be closely related to the synthesis of ethyl butyrate, （E）-2-hexenal, and eucalyptol, respectively.