Brooks Steven A, Huang Li, Herbel Marie N, Gill Bikram S, Brown-Guedira Gina, Fellers John P
Plant Science and Entomology Unit, Department of Plant Pathology, USDA-ARS, Manhattan, KS, 66506, USA.
Theor Appl Genet. 2006 Feb;112(4):618-26. doi: 10.1007/s00122-005-0160-7. Epub 2006 Jan 10.
Genetic mapping and sequencing of plant genomes have been useful for investigating eukaryotic chromosome structural organization. In many cases, analyses have been limited in the number of representatives sampled from specific groups. The degree of intraspecific genome diversity remains in question. The possibility exists that a single model genome may have limited utility for identifying genes in related members of the species or genus. Crop improvement programs have particular interests in disease resistance genes that are harbored by wild relatives of modern cultivated crops. These genes are evolutionarily dynamic and under selective pressure by a broad range of pathogenic organisms. Using resistance gene analogs as models for gene evolution, intraspecific genome comparisons were made among populations of wild diploid wheat (Aegilops tauschii). We observed that deletion haplotypes are occurring frequently and independently in the genome. Haplotypes are geographically correlated and maintenance of gene complements in localized populations indicates selective advantage. Furthermore, deletion haplotypes are not detrimental to plant health, since genes without adaptive value in alternate environments are eliminated from the genome. Deletion haplotypes appear to be a common form of allelic variation in plants, and we address the consequences on genome restructuring and gene evolution.
植物基因组的遗传图谱绘制和测序对于研究真核生物染色体结构组织很有帮助。在许多情况下，分析所选取的特定群体代表性样本数量有限。种内基因组多样性的程度仍有待探讨。单个模式基因组在识别物种或属的相关成员中的基因时，其效用可能有限。作物改良计划尤其关注现代栽培作物野生近缘种所携带的抗病基因。这些基因在进化上具有动态性，且受到多种致病生物的选择压力。以抗病基因类似物作为基因进化模型，对野生二倍体小麦（节节麦）群体进行了种内基因组比较。我们观察到缺失单倍型在基因组中频繁且独立地出现。单倍型与地理因素相关，局部群体中基因互补的维持表明具有选择优势。此外，缺失单倍型对植物健康并无损害，因为在其他环境中没有适应性价值的基因会从基因组中被淘汰。缺失单倍型似乎是植物等位基因变异的一种常见形式，我们探讨了其对基因组重组和基因进化的影响。
