Recent emergence of the wheat Lr34 multi-pathogen resistance: insights from haplotype analysis in wheat, rice, sorghum and Aegilops tauschii
Recent emergence of the wheat Lr34 multi-pathogen resistance: insights from haplotype analysis in wheat, rice, sorghum and Aegilops tauschii
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DOI：
10.1007/s00122-012-2009-1
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发表时间：
2013-03-01
影响因子：
5.4
通讯作者：
Lagudah, Evans S.
中科院分区：
文献类型：
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作者：
Krattinger, Simon G.;Jordan, David R.;Lagudah, Evans S.
自发的序列变化和有益突变的选择是基因多样化的驱动力和进化的关键因素。在高度动态的共同进化过程中，如植物与病原体的相互作用，植物快速适应新出现的病原体的能力是至关重要的。六倍体小麦基因Lr34编码一个三磷酸腺苷结合盒(ABC)转运蛋白，对四种真菌病害具有持久的田间抗性。尽管它在育种和农业中被广泛使用，但在过去的一个世纪里，对Lr34的毒力没有增加的描述。小麦基因库包含两个主要的Lr34等位基因，其中只有一个赋予小麦抗病能力。这两个等位基因位于染色体7DS上，仅有两个外显子多态性不同。在小麦、水稻和高粱的B基因组中发现了Lr34的功能同源基因和直系同源基因，而在玉米、大麦和苔藓中则没有。在这项研究中，我们对小麦、水稻和高粱材料的遗传和地理多样性选择中的同源和直源Lr34基因进行了详细的单倍型分析。我们发现，抗性Lr34单倍型是小麦D-基因组所特有的，在小麦的B-基因组中没有发现，在水稻和高粱中也没有。此外，我们仅在一组252个Ae中发现了易感Lr34等位基因。节节麦基因，小麦D-基因组的祖先。这些数据提供了令人信服的证据，表明Lr34多病原菌抗性是大约8000年前六倍体小麦形成后最近基因多样化的结果。
Spontaneous sequence changes and the selection of beneficial mutations are driving forces of gene diversification and key factors of evolution. In highly dynamic co-evolutionary processes such as plant-pathogen interactions, the plant's ability to rapidly adapt to newly emerging pathogens is paramount. The hexaploid wheat gene Lr34, which encodes an ATP-binding cassette (ABC) transporter, confers durable field resistance against four fungal diseases. Despite its extensive use in breeding and agriculture, no increase in virulence towards Lr34 has been described over the last century. The wheat genepool contains two predominant Lr34 alleles of which only one confers disease resistance. The two alleles, located on chromosome 7DS, differ by only two exon-polymorphisms. Putatively functional homoeologs and orthologs of Lr34 are found on the B-genome of wheat and in rice and sorghum, but not in maize, barley and Brachypodium. In this study we present a detailed haplotype analysis of homoeologous and orthologous Lr34 genes in genetically and geographically diverse selections of wheat, rice and sorghum accessions. We found that the resistant Lr34 haplotype is unique to the wheat D-genome and is not found in the B-genome of wheat or in rice and sorghum. Furthermore, we only found the susceptible Lr34 allele in a set of 252 Ae. tauschii genotypes, the progenitor of the wheat D-genome. These data provide compelling evidence that the Lr34 multi-pathogen resistance is the result of recent gene diversification occurring after the formation of hexaploid wheat about 8,000 years ago.