Rye Pm8 and wheat Pm3 are orthologous genes and show evolutionary conservation of resistance function against powdery mildew
Rye Pm8 and wheat Pm3 are orthologous genes and show evolutionary conservation of resistance function against powdery mildew
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DOI：
10.1111/tpj.12345
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发表时间：
2013-12-01
期刊：
影响因子：
7.2
通讯作者：
Keller, Beat
中科院分区：
文献类型：
--
作者：
Hurni, Severine;Brunner, Susanne;Keller, Beat
通过育种改良小麦在很大程度上依赖于利用相关野生和驯化牧草物种的遗传物质。来自黑麦的1RS染色体臂被导入小麦，并与许多小麦品系杂交，以提高产量和对真菌病害的抗性。Pm8是1RS上的一个白粉病抗性基因，经过广泛的农业栽培，现在已被适应的白粉病小种广泛克服。在这里，我们通过基于同源性的克隆和随后的物理和遗传作图表明，Pm8是小麦抗白粉病基因Pm3等位基因系列的黑麦同源基因。通过瞬时、单细胞表达分析和稳定转化，证实克隆的基因为Pm8。序列分析显示，来自小麦科不同成员的Pm3和Pm8类似基因之间存在着复杂的古代单倍型镶嵌。这些结果表明，这两个基因在750万年前物种分化后独立进化，并保持了它们的抗霉变功能。在这段很长的时间里，共同进化的病原菌没有克服这些基因，这与Pm8自70年前引入商业小麦以来的抗性崩溃形成了强烈的对比。序列比较表明，进化压力作用于两个同源基因相同的亚区和序列特征。这表明它们直接或间接识别在小麦和黑麦的白粉病中保守的相同的病原体效应物。
The improvement of wheat through breeding has relied strongly on the use of genetic material from related wild and domesticated grass species. The 1RS chromosome arm from rye was introgressed into wheat and crossed into many wheat lines, as it improves yield and fungal disease resistance. Pm8 is a powdery mildew resistance gene on 1RS which, after widespread agricultural cultivation, is now widely overcome by adapted mildew races. Here we show by homology-based cloning and subsequent physical and genetic mapping that Pm8 is the rye orthologue of the Pm3 allelic series of mildew resistance genes in wheat. The cloned gene was functionally validated as Pm8 by transient, single-cell expression analysis and stable transformation. Sequence analysis revealed a complex mosaic of ancient haplotypes among Pm3- and Pm8-like genes from different members of the Triticeae. These results show that the two genes have evolved independently after the divergence of the species 7.5 million years ago and kept their function in mildew resistance. During this long time span the co-evolving pathogens have not overcome these genes, which is in strong contrast to the breakdown of Pm8 resistance since its introduction into commercial wheat 70years ago. Sequence comparison revealed that evolutionary pressure acted on the same subdomains and sequence features of the two orthologous genes. This suggests that they recognize directly or indirectly the same pathogen effectors that have been conserved in the powdery mildews of wheat and rye.