病害是影響作物高產(chǎn)穩(wěn)產(chǎn)的重要因素之一,。植物抗病基因 (Plant disease resistance gene,，簡(jiǎn)稱(chēng)R基因)在長(zhǎng)期的進(jìn)化過(guò)程中表現(xiàn)出復(fù)雜的進(jìn)化模式。很多研究表明,，植物R基因是以基因家族的形式存在,，通常成簇排列從而形成復(fù)雜結(jié)構(gòu)。經(jīng)由旁系同源抗病基因間頻繁的序列重組和交換的一類(lèi)抗性基因叫I型R基因,，而較少或沒(méi)有經(jīng)過(guò)旁系同源基因序列重組和交換的基因?yàn)镮I型R基因,。
中國(guó)科學(xué)院植物種質(zhì)創(chuàng)新與特色農(nóng)業(yè)重點(diǎn)實(shí)驗(yàn)室、武漢植物園植物應(yīng)用基因組學(xué)學(xué)科組首席科學(xué)家彭俊華研究員與華中農(nóng)業(yè)大學(xué)長(zhǎng)江學(xué)者匡漢暉教授開(kāi)展合作研究,，通過(guò)分析21個(gè)禾本科物種R基因RP1的序列,，揭示其進(jìn)化模式及在長(zhǎng)期進(jìn)化過(guò)程中的分化機(jī)理。
該研究發(fā)現(xiàn),，RP1基因在禾本科物種中存在著復(fù)雜的復(fù)制,、刪除等遺傳事件，在不同的物種中存在不同的拷貝數(shù),，其祖先物種中僅存在2個(gè)RP1位點(diǎn),，在現(xiàn)有物種中卻存在1-5個(gè)拷貝。在長(zhǎng)期進(jìn)化過(guò)程中因旁系同源基因的重組和交換造成了玉米和小麥基因組中存在多個(gè)RP1同源基因,。頻繁的序列交換和重組并沒(méi)有導(dǎo)致玉米屬不同物種間RP1基因的協(xié)同進(jìn)化,，卻在玉米和高粱屬間存在協(xié)同進(jìn)化的現(xiàn)象。I型和II型R基因很可能在水稻祖先種中已經(jīng)分化,。水稻大部分抗病功能基因家族與其旁系同源基因間存在頻繁的序列交換,，其中Pi37由2個(gè)相鄰的旁系同源基因不對(duì)稱(chēng)交換造成了4個(gè)點(diǎn)突變。
該研究為R基因克隆,、作用機(jī)理及植物R基因工程育種奠定了基礎(chǔ),。相關(guān)研究論文Contrasting Evolutionary Patterns of the Rp1 Resistance Gene Family in Different Species of Poaceae近期發(fā)表于國(guó)際期刊《分子生物學(xué)與進(jìn)化》 Mol. Biol. Evol. （(2011) 28 (1): 313-325）,。（生物谷Bioon.com）
生物谷推薦原文出處：
Mol Biol Evol (2011) 28 (1): 313-325. doi: 10.1093/molbev/msq216
Contrasting Evolutionary Patterns of the Rp1 Resistance Gene Family in Different Species of Poaceae
Sha Luo,1, Junhua Peng?,2, Kunpeng Li1, Min Wang1 and Hanhui Kuang*,1
Abstract
Disease-resistance genes (R-genes) in plants show complex evolutionary patterns. We investigated the evolution of the Rp1 R-gene family in Poaceae, and 409 Rp1 fragments were sequenced from 21 species. Our data showed that the common ancestor of Poaceae had two Rp1 loci, but the number of Rp1 locus in extant species varies from one to five. Some wheat and Zea genotypes have dozens of Rp1 homologues in striking contrast to one or two copies in Brachypodium distachyon. The large number of diverse Rp1 homologues in Zea was the result of duplications followed by extensive sequence exchanges among paralogues, and all genes in maize have evolved in a pattern of Type I R-genes. The high frequency of sequence exchanges did not cause concerted evolution in Zea species, but concerted evolution was obvious between Rp1 homologues from genera Zea and Sorghum. Differentiation of Type I and Type II Rp1 homologues was observed in Oryza species, likely occurred in their common ancestor. One member (Type II R-gene) in the Oryza Rp1 cluster did not change sequences with its paralogues, whereas the other paralogues (Type I R-genes) had frequent sequence exchanges. The functional Pi37 resistance gene in rice was generated through an unequal crossover between two neighboring paralogues followed by four point mutations. The Rp1 homologues in wheat and barley were most divergent, probably due to lack of sequence exchanges among them. Our results shed more light on R-gene evolution, particularly on the differentiation of Type I and Type II R-genes.
