甘薯肌醇-1-磷酸合成酶基因的克隆及序列分析

甘薯(Ipomoea batatas (L.) Lam.)新品系农大603是从感茎线虫(Ditylenchus destructor)病品种徐薯18的辐照后代中获得的一个抗茎线虫病的突变体。以农大603和徐薯18块根的mRNA为模板，根据植物抗线虫病基因NBS保守氨基酸序列设计引物，进行 RT-PCR分析，发现农大603的肌醇-1-磷酸合成酶(Myo inositol-1-phosphate synthase , MIPS)基因的表达量高于徐薯18。采用3'RACE技术扩增出MIPS基因的3'末端cDNA。根据植物MIPS基因 5'端一段保守的氨基酸序列设计兼并引物，并与3'端的特异引物组合，扩增出该基因的5'端cDNA序列。DNA序列比对表明，甘薯MIPS基因与大豆(Glycine max)、番茄(Lycopersicon esculentum )的MIPS基因同源性较高，分别达83.63 %和83.89 %。甘薯MIPS基因全长cDNA的克隆，有利于进一步研究该基因与抗甘薯茎线虫病的关系。

Cloning and Sequence Analysis of Myo Inositol-1-phosphate Synthase Gene in Sweetpotato

Nongda 603, a mutant resistant to sweetpotato stem nematode (Ditylenchus destructor), was obtained from the gamma-irradiated progenies of sweetpotato (Ipomoea batatas (L.) Lam.) cv. Xushu 18 susceptible to the stem nematode. Primers were designed from the NBS (nucleotide-binding site) conserved amino acid sequence of plant nematode resistance genes. The mRNAs of storage roots of Nongda 603 and Xushu 18 were used as temple. RT-PCR analysis indicated that the mRNA abundance of Myo inositol-1-phosphate synthase (MIPS) gene in Nongda 603 was higher than that in Xushu 18. The 3' cDNA of MIPS gene was amplified using 3' RACE and the 5' cDNA of MIPS gene was amplified by PCR using the specific primer of 3' cDNA and the degenerate primer designed based on the conserved amino acid sequence of the 5' end of plant MIPS genes. The DNA sequence alignment showed that sweetpotato MIPS gene had high homology to MIPS genes of soybean (Glycine max) and tomato (Lycopersicon esculentum ) with the identities of 83.63 % and 83.89 %, respectively. The cloning of sweetpotato MIPS gene is useful for the further research of the relationship between sweetpotato MIPS gene and sweetpotato stem nematode resistance.