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甘薯新品系农大603是从感茎线虫病品种徐薯18的辐照后代中获得的一个抗茎线虫病的突变体。根据已报道的植物线虫抗性基因的核苷酸结合位点(NBS)保守氨基酸序列设计兼并引物,用自行改进的SSAP(modified sequence-specific amplification polymorphisms)方法,对农大603和徐薯18的基因组进行PCR扩增,从农大603中扩增出含有抗性基因NBS保守序列的差异片段2个(片段54和片段72)。在GenBank上序列搜索和比对发现,克隆序列与已报道的植物抗病基因之间同源性较低。根据克隆片段的DNA序列设计引物,以抗、感茎线虫病的甘薯品种的基因组DNA为模板进行PCR扩增,结果显示由片段72设计的引物在抗、感品种上没有扩增出多态性带;由片段54设计的引物在抗病品种和感病品种之间扩增出多态性带,推测片段54是与甘薯抗茎线虫病有关的RGA。
A new sweet potato line, Nongda 603, was a mutant against Somnathrix nematophila obtained from the irradiated progeny of Xushu 18, a Stem-nematode species. Based on the published nucleotide sequence of NBS (NBS) conserved amino acid sequence of the plant nematode resistance gene, a series of primers were designed to amplify the genome of Nongda 603 and Xushu 18 by using modified sequence-specific amplification polymorphisms (SSAP) Two PCR products were amplified from Nongda 603, and two different fragments (fragment 54 and fragment 72) containing the NBS conserved sequence of resistance gene were amplified. Sequence search and alignment in GenBank revealed that the homology between the cloned sequence and the reported plant disease resistance gene was low. According to the DNA sequence of the cloned fragment, primers were designed to amplify the genomic DNA of the sweetpotato cultivars with resistant and sensitized stem nematodes. The results showed that the primers designed by the fragment 72 did not amplify the polymorphism ; Primers designed by fragment 54 amplified polymorphic bands between susceptible and susceptible cultivars, suggesting that fragment 54 is an RGA associated with anti-stem nematode disease in sweet potato.