利用RAPD、叶绿体和线粒体基因组PCR-RFLP标记系统评价了大花蕙兰20个品种的遗传多样性.在50个RAPD引物分析中,有36个引物(72.0%)能揭示材料间的多态性,材料间遗传相似系数为0.503~0.765,平均0.598,根据遗传相似系数进行聚类分析表明,RAPD标记能将所有材料区分开.在7个叶绿体基因组(cpDNA)的PCR-RFLP分析中,6个标记(87.5%)可扩增出1至多条清晰的谱带;扩增产物经7种限制性内切酶消化后,6个标记的19种引物/酶组合共检测到53条DNA片段,其中多态性片段有37条,占69.8%;材料间遗传相似系数变化范围为0.571~0.949,平均值为0.766.在8个线粒体基因组(mtDNA)的PCR-RFLP标记分析中,只有3个(37.5%)标记能得到1条清晰的谱带;利用7种限制性内切酶对3个标记的扩增产物消化后,在10种标记/酶组合中,共检测到33条酶切片段,其中21条(63.6%)具有多态性;遗传相似系数为0.634~1.000,平均0.829.这些结果表明,RAPD标记揭示的大花蕙兰遗传多样性最高,其次为cpDNA PCR-RFLP标记,而mtDNA PCR-RFLP标记揭示的遗传多样性最低.
The genetic diversity among 20 Cymbidium accessions was investigated by RAPD markers and PCR-RFLP analyses of organellar DNAs. In RAPD analyses, the amplified products of 36 primers (72. 0% ) were polymorphic. The RAPD-based genetic similarity (GS) among 20 Cymbidium accessions ranged from 0. 503 to 0. 765, with the mean of 0. 598. Based on genetic similarity matrix resulting from RAPD makers, the genetic relationships among 20 Cymbidium accessions were estimated by UPGMA (unweighted pair group method with arithmetic means) clustering analysis. It was found that all 20 Cymbidium accessions could be distinguished by RAPD markers. In cpDNA PCR-RFLP analyses, 6 out of 7 markers (87. 5% ) could produce one or more than one distinct bands by direct electrophoresis in 2% agrose gels. After the amplified products were digested by 7 restriction enzymes, a total of 53 bands were detected in 19 cpDNA PCR-RFLP marker/enzyme combinations, among which 37 bands (69. 8% ) were polymorphic. The cpDNA PCR-RFLP-based genetic similarity (GS) among 20 Cymbidium accessions ranged from 0. 571 to 0. 949, with the mean of 0. 766. Of the 8 mtDNA PCR-RFLP markers, 3 markers (37. 5% ) could produce one distinct band with no polymorphism detected by direct electrophoresis in 2% agrose gels. After the amplified products were digested by 7 restriction enzymes, a total of 33 bands were detected in 10 mtDNA PCR-RFLP marker/enzyme combinations, among which 21 bands (63.6%) were polymorphic. The mtDNA PCR-RFLP-based genetic similarity (GS) among 20 Cymbidium accessions ranged from 0. 634 to 1. 000, with the mean of 0. 829. These results suggested that relatively higher level of genetic polymorphism in Cymbidium could be detected by RAPD markers, whereas relatively lower level genetic polymorphism could be estimated by mtDNA PCR-RFLP markers.