基于叶绿体基因trnL-trnFtrnH-psbAtrnT-trnL序列的甘薯种质遗传多样性分析

Genetic diversity analysis of sweet potato based on chloroplast genes trnL-trnF, trnH-psbA and trnT-trnL sequences

  • 摘要: 【目的】利用叶绿体基因组(cpDNA)的间隔区序列(trnL-trnFtrnH-psbAtrnT-trnL)对甘薯种质进行遗传多样性分析,为其种质保护及开发利用提供理论依据。【方法】以从我国12个省份收集的52份甘薯种质为材料,从10个cpDNA间隔区序列的引物中筛选出能扩增单一、清晰明亮且稳定的序列引物,利用其PCR扩增筛选出间隔区序列,并进行测序及序列拼接。利用DnaSP 5.0进行序列特征分析,采用MEGA X计算52份甘薯种质材料的遗传距离,并构建系统发育进化树。【结果】筛选获得7对扩增结果较理想的引物,其PCR扩增产物经测序分析,共获得3个有效标记(trnL-trnFtrnH-psbAtrnT-trnL)。三者的拼接序列长度为2239 bp,共有7个变异位点,2个单一突变位点,5个简约信息位点,11个插入/缺失位点。在52份甘薯种质材料中,trnL-trnFtrnH-psbAtrnT-trnL序列的变异位点数量(Vs)分别为1、1和5个,单倍型数目(H)分别为2、4和5个,拼接序列的单倍型数目为10个;核苷酸多样性(π)和单倍型多样性(Hdπ)最高的序列分别为trnT-trnLπ=0.00052)和trnH-psbAHd=0.535)。trnL-trnFtrnH-psbAtrnT-trnL序列的Tajima’s D、Fu and Li’s D*和Fu and Li’s F*均无显著差异(P>0.05),符合中性进化模式。基于拼接序列构建的系统发育进化树显示,52份甘薯种质材料的遗传距离为0~1.1848,平均遗传距离0.1018,其分为五大类,其中第Ⅰ类~Ⅳ类仅含有少量种质,其余41份种质归为第Ⅴ类。【结论】52份甘薯种质材料的遗传变异较为丰富,但种质材料间的遗传多样性低,与cpDNA特性和甘薯遗传背景狭窄有关。基于trnL-trnFtrnH-psbAtrnT-trnL的拼接序列更能准确分析甘薯种质的遗传多样性,且有效划分不同类群,为甘薯集团育种提供候选材料。

     

    Abstract: 【Objective】Genetic diversity of sweet potato germplasm was analyzed based on chloroplast genome DNA spacer sequences(trnL-trnF, trnH-psbA and trnT-trnL), to provide theoretical basis for the protection, development and utilization of sweet potato germplasm.【Method】Taking 52 sweet potato materials from 12 different regions in China as the research object. From 10 primers of cpDNA spacer sequence, single, clear, bright and stable sequence primers were selected, and the selected spacer sequences were amplified by PCR, and sequenced and sequence spliced. The sequence features were analyzed by DnaSP 5.0 software. Using MEGA X software to calculate the genetic distance of 52 sweet potato germplasms and build phylogenetic tree.【Result】Seven pairs of primers with ideal amplification results were screened. The PCR amplified products were sequenced and analyzed, and a total of three effective markers(trnL-trnF, trnH-psbA and trnT-trnL) were obtained. The splicing sequence length of the three was 2239 bp, which contained 7 mutation sites, 2 singleton variable sites, 5 parsimony information sites, and 11 insertion/deletion sites. Among the 52 sweet potato materials, the number of variable sites(Vs) of trnL-trnF, trnH-psbA, and trnT-trnL sequences were 1, 1 and 5, respectively. The number of haplotypes(H) for the three were 2, 4 and 5, respectively. The number of haplotypes were 10 after three sequences being merged. The sequences with the highest nucleotide diversity(π) and haplotype diversity(Hdπ) were trnT-trnL(π=0.00052) and trnH-psbA(Hd=0.535). Tajima's D and Fu and Li's D*, Fu and Li's F* values of trnL-trnF, trnH-psbA and trnT-trnL sequences did not reached the level of significant difference(P>0.05), respectively, which indicated that variation of those chloroplast regions followed neutral theory of molecular evolution. Phylogenetic tree constructed based on combination sequences showed that genetic distance of 52 sweet potato varieties was 0-1.1848, and the average genetic distance was 0.1018. The combination sequences divided the test sweet potato varieties into 5 categories.There are only a small amount of germplasms in Type I to Type IV, and the remaining 41 germplasms were classified as Type V.【Conclusion】The genetic variation of 52 sweet potato germplasm materials is relatively rich, but the genetic diversity among germplasm materials is low, which is related to the cpDNA characteristics and the narrow genetic background of sweet potato. The trnL-trnF, trnH-psbA and trnT-trnL combination sequences can be used for sweet potato genetic diversity analysis, and the combination of the three sequences can distinguish the test materials into different groups and provide candidate materials for the next group breeding.

     

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