Functional Differentiation in the Leucine-Rich Repeat Domains of Closely Related Plant Virus-Resistance Proteins That Recognize Common Avr Proteins
Functional Differentiation in the Leucine-Rich Repeat Domains of Closely Related Plant Virus-Resistance Proteins That Recognize Common Avr Proteins
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DOI：
10.1094/mpmi-11-11-0289
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发表时间：
2012-09-01
影响因子：
3.5
通讯作者：
Kobayashi, Kappei
中科院分区：
文献类型：
--
作者：
Sekine, Ken-Taro;Tomita, Reiko;Kobayashi, Kappei
烟叶的N′基因和辣椒的L基因在烟叶病毒外壳蛋白（CP）诱导的超敏反应（HR）中具有抗性反应，但具有不同的病毒特异性。在这里，我们报道了N'基因的鉴定。我们利用L基因序列设计的聚合酶链反应引物扩增并克隆了一个N'候选基因。N'候选基因是一个4143碱基对的单片段，编码1,380个氨基酸的卷曲核苷结合富亮氨酸重复（LRR）型抗性蛋白。候选基因诱导的HR是对多巴病毒CP共表达的响应，其特异性与报道的N′相同。对含N′和对烟叶病毒敏感的烟草植株的分析支持了候选基因是N′基因本身的假设。对N′和L-3的嵌合体分析表明，它们的LRR结构域决定了它们的乙型病毒CP识别谱。对N'和L-3的缺失和突变分析表明，它们c端区域的保守序列在识别常见的无毒蛋白方面具有重要作用，但贡献不同。这些结果共同表明，烟草N'和辣椒L基因很可能从一个共同的祖先进化而来，它们的识别特异性是通过LRR功能结构需求的变化而分化的。
The N' gene of Nicotiana sylvestris and L genes of Capsicum plants confer the resistance response accompanying the hypersensitive response (HR) elicited by tobamovirus coat proteins (CP) but with different viral specificities. Here, we report the identification of the N' gene. We amplified and cloned an N' candidate using polymerase chain reaction primers designed from L gene sequences. The N' candidate gene was a single 4143 base pairs fragment encoding a coiled-coil nucleotide-binding leucine-rich repeat (LRR)-type resistance protein of 1,380 amino acids. The candidate gene induced the HR in response to the coexpression of tobamovirus CP with the identical specificity as reported for N'. Analysis of A N'-containing and tobamovirus-susceptible N. tabacum accessions supported the hypothesis that the candidate is the N' gene itself. Chimera analysis between N' and L-3 revealed that their LRR domains determine the spectrum of their tobamovirus CP recognition. Deletion and mutation analyses of N' and L-3 revealed that the conserved sequences in their C-terminal regions have important roles but contribute differentially to the recognition of common avirulence proteins. The results collectively suggest that Nicotiana N' and Capsicum L genes, which most likely evolved from a common ancestor, differentiated in their recognition specificity through changes in the structural requirements for LRR function.