基于叶绿体DNA分析的辽宁省梨属种质遗传多样性研究

Studies on Genetic Diversity of Pear Germplasm Resources in Liaoning Province of China Based on Chloroplast DNA Analysis

从32对叶绿体DNA通用引物中筛选出8对引物用于评价辽宁省梨属种质的遗传多样性,其中4对引物所扩增的叶绿体DNA片段存在突变位点。合并后的叶绿体基因片段(3 688 bp)含有单一突变位点9个、简约信息性位点3个以及插入/缺失(INDEL)2个。在37个样品中,trnL-trnF-487区域、trnL-trnF-413区域、rbcL区域和trnS-psbC区域的单倍型分别为2个、4个、2个和3个,合并之后的叶绿体基因片段的单倍型为4个。非编码区trnL-trnF-413多态性最高,具有最高的单倍型数、最高的单倍型(基因)多样性、最高的核苷酸多样性、最高的单倍型多样性方差和最高的单倍型多样性标准差。辽宁省37份梨种质的单倍型(基因)多样性(Hd)、核苷酸多样性(Pi)分别为0.577、0.00055。Tajima’s D检验中除了rbcL区域的D值在P<0.05水平上显著外,其余区域的D值未达显著水平,表明自然选择对rbcL区域的突变位点产生了作用。秋子梨和白梨种质共有单倍型HAP_1、HAP_2和HAP_3,显示出一定的亲缘关系;西洋梨则单独共享HAP_5。运用中介邻接网络(Median-Joining network,MJ)算法绘制的中介网络图显示HAP_1与HAP_2、HAP_3的亲缘关系较远,而HAP_5则与上述3个单倍型的亲缘关系较远。

Eight chloroplast DNA(cpDNA)primers were selected from 32 universal primer pairs to assess the genetic diversity of 37 pear accessions in Liaoning Province. Among these primer amplification products,four cpDNA fragments possessed variation sites. Nine singleton variable sites,three parsimony informative sites and two INDELS were obtained from the combined cpDNA fragments(3 688 bp). Two trnL-trnF-487 haplotypes,four trnL-trnF-413 haplotypes,two rbcL haplotypes and three trnS-psbC haplotypes were identified among the 37 pear accessions,respectively,and four haplotypes were identified based on the combined fragments. Non-coding region trnL-trnF-413 exhibited highest polymorphism with the most number of haplotypes,the most abundant haplotype(gene)diversity and nucleotide diversity,the most variant of haplotype diversity and the highest standard deviation of haplotype diversity. Values of haplotype(gene)diversity(Hd)and nucleotide diversity(Pi)of 37 pear accessions in Liaoning Province are 0.577 and 0.00055,respectively. Tajima's test showed all Tajima's D values are not statistical significant except for the rbcL fragment in P < 0.05,indicating that natural selection has an effect on mutations of this fragment. Both P. ussuriensis and P. bretschneideri accessions contained haplotypes HAP_1,HAP_2 and HAP_3,showing a close relationship between them;While HAP_5 is shared by P. communis accessions independently. The network constructed with Median-Joining network calculation exhibited that HAP_1 has a far relationship with HAP_2 and HAP_3,whereas HAP_5 has a far relationship with those three haplotypes mentioned above.