苹果类甜味蛋白编码基因Mdtl2克隆及功能的初步验证

Cloning and characterization of Mdtl2 gene encoding a thaumatin like protein in Malus domestica cv. Fuji

植物类甜味蛋白(Thaumatin like proteins, TLPs)是一类具有抗菌活性和抗非生物胁迫作用的病程相关蛋白。本研究克隆获得富士苹果(Malus domestica cv. Fuji)TLPs家族蛋白Mdtl2编码基因,该基因开放阅读框全长为912 bp,编码303个氨基酸。生物信息学分析显示Mdtl2含有多个保守的半胱氨酸及TLPs家族保守序列片段,且具有TLPs典型的三维结构,属于TLPs家族的糖苷水解酶64家族(GH64-TLP-SF Superfamily)。在烟草中过表达Mdtl2能够显著抑制疫霉(Phytophthora infestans)的侵染。在苹果中过表达Mdtl2显著抑制苹果树腐烂病菌(Valsa mali)的侵染,并且能够诱导胼胝质的积累。上述结果表明,Mdtl2作为糖苷水解酶家族蛋白,能够通过诱导胼胝质的积累,提高植物对病原菌的抗性。

Thaumatin like proteins(TLPs) are a class of pathogenesis-related proteins with antifungal activities and resistance to abiotic stress. In this study, we cloned a TLP, named Mdtl2, which contains an open reading frame of 912 bp, a protein of 303 amino-acid residues. Bioinformatics analysis showed that Mdtl2 contains several conserved cysteines, TLPs family conserved signature sequence, and a typical three-dimensional structure of TLPs. Based on these messages, we speculate that Mdtl2 belongs to GH64-TLP-SF superfamily of TLPs family. Overexpression of Mdtl2 distinctly inhibited the infection of Phytophthora infestans in Nicotiana benthamiana leaves and Valsa mali in apple leaves, respectively. Besides, overexpression of Mdtl2 induced accumulation of callose in apple leaves. Taken together, Mdtl2, as a member of glycoside hydrolase superfamily, enhanced plant resistance to pathogens by inducing the production of callose.