草莓9–顺式–环氧类胡萝卜素双加氧酶基因FaNCED的克隆及表达分析

 采用RT-PCR和RACE技术从草莓果实中克隆ABA合成途径中关键基因FaNCED，该cDNA全长2 228 bp，具有完整的开放阅读框（ORF），共1 827个碱基，编码609个氨基酸。序列分析表明，FaNCED编码的氨基酸序列与其他植物的NCED蛋白有很高的同源性。系统进化树分析显示，草莓NCED与同为蔷薇科的湖北海棠聚为一类，与橙、柠檬、温州蜜柚、葡萄等非跃变型果实NCED蛋白亲缘关系较近。实时荧光定量PCR分析发现，FaNCED基因在草莓根、茎、叶、花萼和果实中都有表达；在果实成熟过程中FaNCED的表达出现两次高峰，分别在大白果期和红果期，且在红果期表达量最高，并与ABA积累相吻合；FaNCED在果实采后1 d表达略有下降，之后急剧上升，ABA含量变化与FaNCED基因的表达基本一致。FaNCED可能参与调控ABA的合成并在草莓成熟中起一定作用。

Cloning and Expression Analysis of 9-cis-epoxycarotenoid Dioxygenase Gene FaNCED in Strawberry

The FaNCED gene cDNA sequence was cloned from strawberry fruit(Fragaria× ananassa)using RT-PCR and RACE techniques.The cDNA sequence consists of 2 228 bp with an intact open reading frame of 1 827 bp,encoding a polypeptide of 609 amino acids.Homology analysis showed that the deduced NCED protein was highly homologous to other NCED proteins from different plant species.Phylogenetic analysis indicated that FaNCED and NCED of Malus hupehensis was gather to a same group and was more related to other NCED of nonclimacteric fruits including orange,lemon, Wenzhou pomelo and grape.Real-time PCR analysis revealed FaNCED could be expressed in different strawberry tissues including root,stem,leaf,calyx and fruit.The expression level of FaNCED has two peak during the whole period of strawberry fruit development and reached the maximum at the red ripening stage.The expression level of FaNCED gene decreased 1 d after harvest,but sharply increased later on.ABA content was consistent with the expression level of FaNCED.FaNCED may participate in ABA biosynthesis and play a role in the fruit ripening.