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RAPD-PCR to detect genomic polymorphisms among geographically-dispersed populations of Cephus cinctus.

机译：RAPD-PCR检测在地域分布的Cephus cinctus人群中的基因组多态性。

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摘要

Wheat stem sawfly, Cephus cinctus Norton, is the most destructive chronic insect pest of wheat in the northern Great Plains. However, little is known about the extent and distribution of genetic variability in the species. Over the past 20 years in Montana, C. cinctus has changed from an insect pest exclusive to spring wheat to a pest which causes major economic damage in both spring and winter wheat. Preliminary examination suggests that phenology and maturity of wheat cultivars grown in Montana has not changed enough over this period to account for the difference in insect virulence. Knowledge of the genetic variability within endemic populations of C. cinctus is important for developing management and resistance-breeding strategies. Our objective in this study was to assay the genomic variability within and among geographically-dispersed collections of C. cinctus from the northern U.S. Great Plains using RAPD-PCR markers. Overwintering sawfly larvae were collected from wheat stubble at eight sites in Montana, six sites in North Dakota, and one site in Wyoming. DNA was extracted and evaluated from individual larvae from each collection site. Sixty-two random decamer primers were screened and 20 of them consistently produced well-amplified and reproducible polymorphic bands. The size of amplified DNA fragments produced by these primers ranged from 200-1900 bp, with individual primers generating from two to nine bands. Genetic distances among 186 individuals based on 60 RAPD loci were calculated using similarity index, 1-M (where M is the fraction of matches). Each sawfly individual was a unique RAPD multiband phenotype. Based on UPGMA cluster analysis all Montana sawflies clustered separately from all North Dakota and Wyoming sawflies. Principal coordinate analysis based on the band frequency within each population showed a similar result. Analysis of molecular variance partitioned the RAPD variation into the among- and within-population components. The within-population component accounted for 71.6% of the variation and was significantly different from zero at the 1% probability level. The among-population and among-region components accounted for 6.3% and 22.1% of the total variation, respectively. Subset analyses of MT and ND populations showed that there were significant differences among populations in MT but not in ND. Pairwise tests for the homogeneity of the RAPD variance between populations suggested significant divergences among 81 of the 105 (77%) population pairs including all but three of the MT pairwise comparisons. A dendrogram based on the Euclidean distance among populations showed that all the Montana populations were grouped together, with all North Dakota populations in another group. The high degree of structuring in Montana populations suggests the high degree of reproductive isolation among geographically-separated populations is contributing to development of geographic and/or host races due to adaptation to local environment conditions and/or host differences.
机译：小麦茎锯蝇Cephus cinctus Norton是北大平原北部最具破坏性的小麦慢性害虫。但是，人们对该物种遗传变异的程度和分布知之甚少。在过去的20年中，蒙大拿州的C. cinctus已经从春季小麦专用的害虫变成了对春季和冬季小麦造成重大经济损失的害虫。初步检查表明，在此期间，蒙大拿州种植的小麦品种的物候和成熟度变化不大，不足以解释昆虫毒力的差异。对C. cinctus特有种群内的遗传变异性的了解对于制定管理和抗性育种策略很重要。这项研究的目的是使用RAPD-PCR标记分析美国北部大平原地区C. cinctus地理上分散的集合内及其之间的基因组变异性。从蒙大拿州八个地点，北达科他州六个地点和怀俄明州一个地点的麦茬中收集了越冬的锯蝇幼虫。从每个收集部位的幼虫中提取DNA并进行评估。筛选了62条随机的decamer引物，其中20条一致产生了扩增良好且可再现的多态性条带。这些引物产生的扩增DNA片段大小在200-1900 bp之间，单个引物产生2至9个条带。使用相似性指数1-M（其中M是匹配的分数）来计算基于60个RAPD基因座的186个个体之间的遗传距离。每个锯fly个体都是独特的RAPD多带表型。根据UPGMA聚类分析，所有蒙大拿州锯齿动物与所有北达科他州和怀俄明州锯齿动物分别聚类。基于每个人群中的频带频率的主坐标分析显示了相似的结果。分子变异分析将RAPD变异分为种群内和种群内成分。人口内部因素占变异的71.6％，在1％的概率水平下与零显着不同。人口中和区域中的分量分别占总变异的6.3％和22.1％。对MT和ND人群的子集分析表明，MT人群之间存在显着差异，而ND人群之间没有显着差异。群体间RAPD方差的同质性的成对检验表明，在105个群体（77％）的群体对中，有81个（77％）群体之间存在显着差异，其中包括除MT配对之外的所有三个群体。根据人口之间的欧几里得距离进行的树状图显示，所有蒙大拿州的人口都分组在一起，而北达科他州的所有人口都属于另一组。蒙大拿州种群的高度结构化表明，由于适应当地环境条件和/或宿主差异，地理上分离的种群之间的高度生殖隔离正在促进地理和/或寄主种族的发展。

著录项

  • 作者

    Lou, Kuifu.;

  • 作者单位

    Montana State University.;

  • 授予单位 Montana State University.;
  • 学科 Biology Molecular.;Biology Genetics.;Biology Entomology.
  • 学位 Ph.D.
  • 年度 1997
  • 页码 98 p.
  • 总页数 98
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类
  • 关键词

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