关键词: 猕猴桃, D–半乳糖醛酸还原酶, 原核表达, Western 杂交, 维生素C

Abstract: In present study，D-galacturonate reductase（GalUR）cDNA were cloned from young fruit of Actinidia deliciosa‘Qinmei’，expressed it in E. coli，and prepared the specific antibody，then we analyzed the relationship between its transcript level and AsA level during fruit development and among different tissues of kiwifruit. The results showed that cDNA of GalUR from young fruit of kiwi had an 990 bp open reading frame（ORF） and encoded a protein of 329 amino acid residues with a putative molecular mass of 37 kD. Its accession No. in GenBank is GU339035. Both of its cDNA and amino acid sequence showed high similarity with GalUR genes reported in other plants，e.g. strawberry. After it was heterologously expressed in E. coli，the fusion protein GalUR-His（His is about 21 kD）was about 58 kD，and existed mainly as inclusion body. Western blotting showed that the antibody prepared in rabbit reacted specifically with protein extracted from kiwifruit tissues，and the size of GalUR protein in kiwifruit was also about 37 kD. Although GalUR expression levels had a good consistency with AsA content during fruit development and among different tissues of kiwi，the ratio of AsA produced from D-galacturonate was much lower than that from L-galactose by feeding experiment. These results suggest that GalUR in kiwifruit，as a monomer protein，has a good correlation with AsA content，but it is not a main controlling point in regulating AsA accumulation in kiwifruit. 　　

Key words: kiwifruit, D-galacturonate reductase, prokaryotic expression, Western blotting, vitamin C