摘要
The objectives of this study were to isolate and characterize microsatellites from a heat tolerant variety of snap bean (Phaseolus vulgaris L.) in order to generate polymorphic genetic markers linked to quantitative trait loci for heat tolerance. A genomic library contained 400-800 bp inserts was constructed and screened for the presence of (GA/CT) n and (CA/GT) n repeats. The proportion of positive clones yielded estimated of 3.72×10 4 such dinucleotide repeats per genome, roughly comparable to the abundance reported in other eukaryotic genomes. Twenty_six positive clones were sequenced. In contrast to mammalian genomes, the (GA/CT) n motif was much more abundant than the (CA/GT) n motif in these clones. The (GA/CT) n repeats also showed longer average repeat length (mean n =10.4 versus 6.5), suggesting that they are better candidates for yielding polymorphic genetic markers in the snap bean genome.
从耐高温型菜豆 (PhaseolusvulgarisL .)品种“Haibushi”基因组分离微卫星DNA ,可以提供与耐热性QTL(quantitativetraitlocus)连锁的多态遗传标记。为此 ,利用lambdaZAPⅡ载体构建了一个包含 40 0～ 80 0bp插入片段的菜豆基因组文库。利用地高辛末端标记寡聚核苷酸 (GA) 10 和 (CA) 10 作为探针筛选该文库 ,并对部分阳性克隆进行测序分析 ,结果如下 :获得了一个含 1.12 5× 10 6pfu (plaqueformingunit)的基因组文库 ,其中约有 3.72× 10 4 pfu含(GA) n 或 (CA) n 微卫星DNA ,即 16 .7kb菜豆基因组DNA就含有一个 (GA) n 或 (CA) n 微卫星DNA。测序分析了 2 6个阳性克隆 ,每个克隆含有 1个或 1个以上的微卫星DNA ,一共得到 35个微卫星DNA。其中 17个为单一重复子 ,18个为复合重复子。在 35个微卫星DNA中 ,2 6个为 (GA) n 重复子 ,占 81%。表明在菜豆基因组中 (GA) n 比 (CA) n的丰度要高得多。其中 13个 (GA) n 的长度等于或大于 2 0bp ,相当于每 33.4kb基因组DNA含 1个。 (GA) n 重复子的平均长度n =10 .4,明显高于 (CA) n 重复子的平均长度n =6 .5 ,表明 (GA) n 重复子更适合于用作遗传标记。
基金
AGrantfromJapanInternationalResearchCenterforAgriculturalSciences
fundpartlyfromtheBioorientedTechnologyResearchAdvancement
