Tommasini L, Yahiaoui N, Srichumpa P, Keller B
Plant Molecular Biology Department, Institute of Plant Biology, University of Zürich, Zollikerstr. 107, 8008, Zürich, Switzerland.
Theor Appl Genet. 2006 Dec;114(1):165-75. doi: 10.1007/s00122-006-0420-1. Epub 2006 Oct 25.
In the ideal case, molecular markers used for marker-assisted selection are allele-specific even if the alleles differ only by a few nucleotide polymorphisms within the coding sequence of target genes. Such 'perfect' markers are completely correlated with the trait of interest. In hexaploid wheat (Triticum aestivum L.) the Pm3 locus encodes seven alleles (Pm3a-Pm3g) conferring resistance to different races of Blumeria graminis f.sp. tritici, the agent of powdery mildew, a major disease of bread wheat. All Pm3 alleles are known at the molecular level. Here, we generated specific markers for the Pm3 alleles based on nucleotide polymorphisms of coding and adjacent non-coding regions. The specificity of these markers was validated in a collection of 93 modern or historically important cultivars and breeding lines of wheat and spelt (Triticum spelta L.). These markers confirmed the presence of the predicted Pm3 alleles in 31 varieties and lines known to carry Pm3 resistance alleles. In a few varieties, Pm3 alleles different from alleles previously described based on pathogenicity tests or tightly linked markers were observed. In all these cases, the identity of the marker-detected Pm3 alleles was confirmed by DNA sequence analysis. Pm3 markers confirmed the absence of known Pm3 resistance alleles in 54 European wheat and spelt varieties in which Pm3 alleles had not been previously identified. These results indicate that the developed markers are highly diagnostic for specific Pm3 resistance alleles in a wide range of varieties and breeding lines, and will be useful (1) for identifying Pm3 alleles in the wheat gene pool, (2) for efficient marker-assisted selection of these genes, and (3) for combining multiple Pm3 alleles within a single cultivar through transgenic approaches.
在理想情况下，用于标记辅助选择的分子标记即使等位基因仅在目标基因编码序列内存在少数核苷酸多态性，也是等位基因特异性的。这种“完美”标记与目标性状完全相关。在六倍体小麦（普通小麦）中，Pm3位点编码七个等位基因（Pm3a - Pm3g），赋予对小麦白粉病菌（小麦白粉病的病原菌，是面包小麦的一种主要病害）不同生理小种的抗性。所有Pm3等位基因在分子水平上都是已知的。在此，我们基于编码区和相邻非编码区的核苷酸多态性，为Pm3等位基因生成了特异性标记。这些标记的特异性在93个现代或具有历史重要性的小麦和斯佩尔特小麦（斯佩尔特小麦）品种及育种系中得到了验证。这些标记证实了在已知携带Pm3抗性等位基因的31个品种和品系中存在预测的Pm3等位基因。在少数品种中，观察到了与先前基于致病性测试或紧密连锁标记所描述的等位基因不同的Pm3等位基因。在所有这些情况下，通过DNA序列分析证实了标记检测到的Pm3等位基因的身份。Pm3标记证实了在54个欧洲小麦和斯佩尔特小麦品种中不存在已知的Pm3抗性等位基因，这些品种此前未鉴定出Pm3等位基因。这些结果表明，所开发的标记对于广泛的品种和育种系中的特定Pm3抗性等位基因具有高度诊断性，并且将有助于（1）在小麦基因库中鉴定Pm3等位基因，（2）对这些基因进行高效的标记辅助选择，以及（3）通过转基因方法在单个品种中组合多个Pm3等位基因。
