Abstract：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.
