野生大豆抗胞囊线虫基因SHMT的序列多样性

Sequence diversity of resistance gene SHMT to soybean cyst nematode among wild soybeans

大豆丝氨酸羟基转移酶(serine hydroxymethyltransferase)基因(SHMT)是Rhg4位点的抗胞囊线虫基因。本研究根据基因序列设计PCR引物对92份野生大豆进行了扩增,并对扩增产物测序,研究了其遗传多样性及其与大豆对胞囊线虫抗性的关系,旨在为野生大豆资源的合理利用提供参考。在供试的92份野生大豆SHMT序列(2 430bp)中,共发现了13个SNP位点(7个转换,6个颠换)和4个Indel(均发生在非编码区),其中11个为简约信息位点;SHMT序列多样性为π=0.000 61和θ=0.001 06;多态性位点形成16个单倍型,其中9个单倍型的分布频率>2%,单倍型多样性为0.855;Tajima’s D、Fu and Li’s D和Z检验发现野生大豆SHMT不存在选择压力;卡方测验表明野生大豆SHMT与大豆对胞囊线虫的抗性没有直接关联;采用UPGMA法构建的SHMT分子进化树表明,供试92份野生大豆被聚类在6个类群,并表现出种质间的遗传关系与其生态区有一定的联系。

SHMT was cloned from soybean variety Forrest and reported as an SCN resistance gene at Rhg4 lo- cus. SHMT of 92 wild soybean accessions were sequenced and their sequence diversity was analysed. A total of 13 SNPs （7 transitions and 6 transversions） and 4 Indels （all in the noneoding region） were identified, 11 of them were parsimony informative sites. Sequence diversity analysis among 92 wild soybean genotypes showed π = 0.000 61 and 0 = 0. 001 06 for SHMT. The 17 DNA variations formed 16 haplotypes, of which 9 haplotypes existed in 2 or more wild soybeans, haplotype diversity was 0.855. 3 neutrality tests （ Tajima＇ s D, Fu and Li＇ s F, and Z test） were not significant for the gene in these 92 wild soybean genotypes, suggesting there was no selection pressure on it. X2 text for distribution of alleles in resistant and susceptible accessions indicated that SHMT had no correlation with wild soybean resistance to soybean cyst nematode. 92 wild soybeans were grouped into 6 clusters using UPGMA method, some relationship was found between their origin and their genetic relationship.