A novel model system to study the rapid diversification of R genes

研究 R 基因快速多样化的新模型系统

• 批准号: 22657015
• 负责人: TASAKA Masao
• 金额: $ 2.27万
• 依托单位: Nara Institute of Science and Technology
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Challenging Exploratory Research
• 财政年份: 2010
• 资助国家: 日本
• 起止时间: 2010 至 2011
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-22657015/
• 关键词: シロイヌナズナ; R遺伝子; UNI遺伝子; 遺伝子内変異; 変異率; uni-1D; サプレッサー; 変異頻度; EMS; サリチル酸; ATR; ATM; Rタンパク質; UNI; 2重鎖切断

Plants use disease resistance(R) genes, most of which encode nucleotide-binding leucine-rich repeat(NB-LRR) protein, to recognize pathogens. Each R protein recognizes the specific effector protein. To counter the rapid diversification of pathogen effector genes, it thought that R genes also evolve rapidly. This idea is supported that high degree of polymorphism is observed in R-genes. However, little is known about the mechanisms underlying the R-gene diversification. We analyzed Arabidopsis uni-1D mutant, harbors a semi-dominant and gain-of-function allele of UNI gene, an R gene that has a NB-LRR-related structure. The uni-1D has a constitutively active R protein to induce resistance responses without any pathogen infection. Furthermore, uni-1D heterozygous mutant(hereafter uni1D/+) shows rapidly consume stem cells in the shoot apical meristem of the inflorescence stem, resulting in formation of very short stem. Interestingly, under normal growth condition, we infrequently but repeate … More dly observed that uni-1D/+produced chimeric sectors display the morphology of wild-type-like long inflorescence stem. When we checked nucleotide sequences in this chimeric stem, we always found additional mutations, which presumably disrupted the uni-1D protein function. This reversion event occurs less than 0. 5% of individuals among the population. When we tried with EMS, an alkylating agent, we succeeded to increase the reversion frequency about 30%. Furthermore, when we treated uni-1D/+with zeocin, which causes DNA double-strand breaks, or hydroxyurea(HU), which induces defects of DNA repair and replication by depletion by depleting deoxynucleotide triphosphate pools, the reversion frequency significantly increased. These suggest that the uni-1D systems can easily and efficiently detect various types of nucleotide alterations in the uni-1D gene. Currently, we are analyzing molecular mechanisms underlying the rapid diversification of R genes using this system and our preliminary results imply the involvement of DNA repair machinery in this phenomenon. Less

植物利用抗病基因（R）识别病原体，其中大部分基因编码核苷酸结合富亮氨酸重复序列（NB-LRR）蛋白。每个R蛋白识别特定的效应蛋白。为了应对病原体效应基因的快速多样化，它认为R基因也在快速进化。这一观点支持了在R基因中观察到高度多态性的观点。然而，对R基因多样化的机制知之甚少。我们分析了拟南芥uni-1D突变体，该突变体含有UNI基因的一个半显性和功能获得性等位基因，UNI基因是一个具有NB-LRR相关结构的R基因。uni-1D具有组成型活性R蛋白，可诱导抗性反应，而无需任何病原体感染。此外，uni 1D杂合突变体（以下简称uni 1D/+）表现出快速消耗花序茎的茎尖分生组织中的干细胞，导致形成非常短的茎。有趣的是，在正常的生长条件下，我们很少但重复 ...更多信息 dly观察到单1D/+产生的嵌合区段显示野生型样长花序茎的形态。当我们检查这个嵌合茎中的核苷酸序列时，我们总是发现额外的突变，这可能会破坏uni-1D蛋白的功能。此还原事件发生的时间小于0。占人口的5%。当我们尝试使用EMS（一种烷基化剂）时，我们成功地将回复频率提高了约30%。此外，当我们用博莱霉素（其导致DNA双链断裂）或羟基脲（HU）（其通过消耗脱氧核苷酸三磷酸池而通过消耗诱导DNA修复和复制缺陷）处理uni-1D/+时，回复频率显著增加。这些表明，uni-1D系统可以容易和有效地检测uni-1D基因中的各种类型的核苷酸改变。目前，我们正在使用该系统分析R基因快速多样化的分子机制，我们的初步结果表明DNA修复机制参与了这一现象。少

项目成果

A novel model system to study the diversification of R genes

研究 R 基因多样化的新模型系统

• 发表时间: 2012
• 作者: Uchida N.;Ogawa T.;Igari K.;Tasaka M.
• 通讯作者: Tasaka M.