茶树类防御素CsDEF2基因的克隆与序列及表达分析

Cloning,Sequence and Expression Analysis of Defensin-like CsDEF2 Gene in Camellia sinensis

防御素(Defensin)是一类广泛存在动植物中的阳离子短肽,具有多种防御功能。本研究利用转录组数据库,从茶树叶片中克隆了一个类防御素基因CsDEF2并对该基因进行了生物信息学分析,CsDEF2的开放阅读框(ORF)全长246 bp,编码81个氨基酸,蛋白分子量8.68 kD,等电点9.12.序列比对和系统发育分析表明,CsDEF2是防御素家族中的新成员。此外,本研究对病原真菌(茶树镰刀菌)侵染后的茶树叶片中该基因的表达水平进行半定量分析。结果表明,茶树镰刀菌侵染的叶片CsDEF2基因的表达量相较未侵染叶片明显上调,说明CsDEF2基因可能在防御真菌侵染发挥作用。以上研究结果为提高茶树及其它作物的生物抗性提供了新的靶基因,同时也为探讨茶树生物抗性奠定了基础,具有重要的理论与应用价值。

Defensins are small cationic proteins that are ubiquitously present in both plants and animals and they play significant roles on the bio-resistance. In this study, the coding sequences of Camellia sinensis defensins-like gene(CsDEF2) was cloned and identified. The open reading frame of CsDEF2 consisted of 246 bp and polypeptides encoded 81 amino acids with a deduced molecular weight of 8.6 kD and the theoretical isoelectric point of9.12. Multiple alignments and phylogenetic analysis strongly suggested that CsDEF2 was a new member of the defensin family. Additionally, the expression level of Cs DEF2 was studied in leaves of tea plant inoculated with Fusarium roseum. The expression level of CsDEF2 in leaf was significantly upregulated after infection by pathogenic fungus. The results suggested that CsDEF2 might play a role of positive regulation in the response to fungus infection. The above findings provided a new target gene for enhancing the biotic resistance in tea plants and other crops, and also laid a foundation for exploring the biological resistance of tea plants, with an important theoretical and practical value.