桑树乳汁蛋白基因MLX56的克隆及生物学功能分析

Cloning and Biological Function Analysis of Mulberry Latex Protein Gene MLX56

MLX56是一种分子质量为56 k D,对多种鳞翅目昆虫具有毒性的桑树韧皮部汁液蛋白。利用PCR技术从桑品种湖桑32号的桑树叶片中克隆了MLX56基因,命名为Ma MLX56(Gen Bank登录号:JX432966)。该基因编码区全长为1 203 bp,编码蛋白质含有400个氨基酸,有3个典型的保守结构域,具有信号肽序列,是一种分泌型蛋白质。将克隆得到的Ma MLX56编码区片段插入植物表达载体p BI121,构建植物表达载体p BI121-Ma MLX56,并转化拟南芥获得了转基因植株。转基因拟南芥分别接种甘蓝蚜(Brevicoryne brassicae)和丁香假单胞菌番茄致病变种(Pseudomonas syringae pv.Tomato DC3000,Pst DC3000)后,植株呈现出较强的抗虫性和抗Pst DC3000侵染能力,推测Ma MLX56在桑树响应生物胁迫过程中具有重要作用。

MLX56 is a latex protein with molecular weight of 56 k D which shows toxicity to many lepidopteran insects. MLX56 gene was cloned from mulberry leaf of Husang 32 using PCR technology and designated as Ma MLX56（ Gen Bank accession No. JX432966）. The ful-length coding region of Ma MLX56 was 1 203 bp which encodes a 400 amino acid protein with three typically conserved domains and a signal peptide,showing that it is a secretory protein. The coding region of Ma MLX56 was inserted into plant expression vector p BI121 to construct recombinant expression vector p BI121-Ma MLX56 which was then transformed into Arabidopsis thaliana to generate transgenic plants containing Ma MLX56 gene. The transgenic plants showed strong resistance to Brevicoryne brassicae and Pseudomonas syringae pv. Tomato DC3000（ Pst DC3000） invasion,indicating that Ma MLX56 plays an important role in response of mulberry to biotic stress.