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利用398对BNL、JESPR、TMB等SSR引物,对不同亲本来源、不同选育时期、不同种植生态区的43份陆地棉基础种质进行了遗传多样性的SSR分子标记分析。扩增产物用8%的非变性聚丙烯酰胺凝胶检测,银染观察并照相。遗传多样性带型分析按位点多态信息量(PIC),Shannon-weaver多样性指数(H’)等方法,利用NTSYSpc2.1软件计算品种间的遗传相似系数(Jaccard系数),并用类平均法(UPGMA)进行聚类。结果表明所选择多态性引物分布在棉花基因组的第3、4、5、8、9、10、16、18、20、23号等染色体上,36对多态性引物在基础种质中扩增等位基因130个,其中多态性等位基因占80%,每个引物扩增等位基因2～8个,平均3.6个,PIC为0.278～0.865,平均0.62,基因型多样性(H’)为0.451～2.039,平均1.102,基础种质间SSR遗传相似系数平均为0.610,变幅为0.409～0.865,这说明所选基础种质基因组水平的多样性较丰富,变化范围大、代表性强。按品种不同选育时期来讲,第一、二、三期基础种质的SSR分子标记平均遗传相似系数分别是0.587、0.630、0.630,说明现代基础种质比早期基础种质在基因组水平的差异呈下降的趋势,可能是由于育种者偏重于使用优质高产性状的亲本品种,致使我国棉花的育种基础逐渐变窄。不同棉区基础种质SSR标记性状差异大,北部特早熟棉区基础种质间的SSR标记的多样性大于黄河、长江棉区,主要原因是长江、黄河棉区的育种过分强调高产、优质品种选育,品种间的差异变小;基础种质中的国内品种SSR相似系数(0.624)比引进品种(0.585)高,说明国内品种在遗传多样性上目前还没有超越国外品种。总之,我国棉花现代基础种质比早期基础种质的遗传多样性呈下降的趋势,黄河、长江主产棉区基础种质的遗传多样性还没有超过国外基础种质,品种间的遗传背景较为狭窄,还必须采用多种途径丰富我国棉花种质资源的遗传多样性。
Using SSR primers such as BNL, JESPR and TMB, 398 SSR markers were used to analyze the genetic diversity of 43 upland cotton germplasms from different parental origins, different breeding periods and different planting ecological zones. Amplification products were detected with an 8% non-denaturing polyacrylamide gel and silver staining was observed and photographed. Genetic diversity banding analysis The genetic similarity coefficient (Jaccard coefficient) among cultivars was calculated by NTSYSpc2.1 software according to PIC, Shannon-weaver diversity index (H ’ Method (UPGMA) for clustering. The results showed that the selected polymorphic primers were distributed on chromosomes 3, 4, 5, 8, 9, 10, 16, 18, 20 and 23 of the cotton genome, and 36 pairs of polymorphic primers were amplified in the basic germplasm 130 alleles were amplified, of which 80% were polymorphic alleles. The average number of alleles per primer ranged from 2 to 8, with an average of 3.6. The PIC ranged from 0.278 to 0.865 with an average of 0.62. The genotype diversity (H ’) Ranged from 0.451 to 2.039 with an average of 1.102. The average SSR genetic similarity coefficient of basic germplasm was 0.610 and the amplitude ranged from 0.409 to 0.865, which indicated that the diversity of selected basic germplasm genomes was rich, the range of variation was large, Strong. The average genetic similarity coefficient of the SSR markers of the first, second and third basic germplasms according to the different breeding periods of the cultivars were 0.587, 0.630 and 0.630, respectively, indicating that the difference of the modern basic germplasm at the genome level The declining trend may be due to the breeders favoring the use of high-yielding traits of parental varieties, resulting in a gradual narrowing of the breeding base for cotton in China. The SSR markers of basic germplasms differ greatly in different cotton regions. The diversity of SSR markers in basic germplasm in North precocious cotton regions is greater than that in Yellow River and Yangtze River cotton regions. The main reason is that the breeding of the Yangtze River and Yellow River cotton regions overemphasizes the high-yielding and high-quality varieties The difference of SSR among breeds was less than that of other breeds. The SSR similarity coefficient (0.624) of domestic breeds was higher than that of introduced breeds (0.585) in basic germplasm, which indicated that domestic breeds did not surpass foreign breeds in genetic diversity at present. In short, the genetic diversity of modern Chinese cotton base germplasm is lower than that of the early basic germplasm. The genetic diversity of the basic germplasm in the main cotton producing areas of the Yellow River and Yangtze River has not exceeded the basic germplasm of foreign countries, and the genetic background among the varieties is relatively Narrow, but also must use a variety of ways to enrich the genetic diversity of China’s cotton germplasm resources.