Bechsgaard Jesper, Jorgensen Tove Hedegaard, Schierup Mikkel Heide
Department of Bioscience, Aarhus University, 8000 Aarhus C, Denmark
Department of Bioscience, Aarhus University, 8000 Aarhus C, Denmark.
G3 (Bethesda). 2017 Aug 7;7(8):2677-2683. doi: 10.1534/g3.117.043984.
The generation and maintenance of functional variation in the pathogen defense system of plants is central to the constant evolutionary battle between hosts and parasites. If a species is susceptible to a given pathogen, hybridization and subsequent introgression of a resistance allele from a related species can potentially be an important source of new immunity and is therefore expected to be selected for in a process referred to as adaptive introgression. Here, we survey sequence variation in 10 resistance (-) genes and compare them with 37 reference genes in natural populations of the two closely related and interfertile species: and The -genes are highly polymorphic in both species and show clear signs of -species polymorphisms. We show that and A. have had a history of limited introgression for the reference genes. For the -genes, the introgression rate has been significantly higher than for the reference genes, resulting in fewer fixed differences between species and a higher sharing of identical haplotypes. We conclude that -genes likely cross the species boundaries at a higher rate than reference genes and therefore also that some of the increased diversity and -specific polymorphisms in -genes is due to adaptive introgression.
植物病原体防御系统中功能变异的产生和维持是宿主与寄生虫之间持续进化斗争的核心。如果一个物种对特定病原体敏感，那么来自相关物种的抗性等位基因的杂交及随后的渐渗可能是新免疫的重要来源，因此有望在一个被称为适应性渐渗的过程中被选择。在此，我们调查了10个抗性（-）基因的序列变异，并将它们与两个密切相关且可育的物种自然种群中的37个参考基因进行比较： 和 。-基因在两个物种中都高度多态，并显示出明显的-物种多态性迹象。我们表明， 和 对参考基因的渐渗历史有限。对于-基因，渐渗率显著高于参考基因，导致物种间固定差异较少，相同单倍型的共享率更高。我们得出结论，-基因跨越物种边界的速率可能高于参考基因，因此-基因中一些增加的多样性和-特异性多态性也是由于适应性渐渗。
