Zhao Lina, Zhang Qijun, Gao Rongchao, Yang Sihai, Liu Haoxuan, Zhang Xiaohui
State Key Laboratory of Pharmaceutical Biotechnology, School of Life Sciences, Nanjing University, Nanjing, 210000, China.
Jiangsu Academy of Agricultural Sciences, Nanjing, 210000, China.
BMC Evol Biol. 2015 Sep 30;15:215. doi: 10.1186/s12862-015-0493-z.
Three NBS-LRR genes, Rpi-blb2, Mi-1.2, and Cami, constitute a very special plant resistance gene family. These genes confer resistance against 4 distantly related pathogen species in 3 different Solanaceae hosts. To characterize this noted resistance, we conducted a series of studies on this gene family.
First, homologs of this gene family were identified in the pepper, tomato and potato genomes. This revealed a large variation in copy number within this gene family among species and a great divergence was found both between and within species. To gain more information pertaining to gene resistance within this family, 121 LRR regions were cloned in 16 different wild/cultivated potato accessions. Again, frequent copy number variations and a high level of divergence between homolog were observed common among accessions. The divergence within species was so high that it reaches the level of divergence between species. Also, frequent frameshift mutations and abundant gene conversion events were identified in these LRR regions.
Our findings suggest that this family harbors an unusually high level of genetic abundance, making it of particular interest. Together with other reported examples, our study also provides evidence that multi-resistance is a common trait in R gene families like this.
三个NBS-LRR基因，即Rpi-blb2、Mi-1.2和Cami，构成了一个非常特殊的植物抗性基因家族。这些基因赋予了三种不同茄科宿主对4种远缘病原体物种的抗性。为了表征这种显著的抗性，我们对这个基因家族进行了一系列研究。
首先，在辣椒、番茄和马铃薯基因组中鉴定出了这个基因家族的同源物。这揭示了该基因家族在物种间拷贝数的巨大差异，并且在种间和种内都发现了很大的分歧。为了获得更多关于该家族内基因抗性的信息，在16个不同的野生/栽培马铃薯种质中克隆了121个LRR区域。同样，在种质中普遍观察到频繁的拷贝数变异和同源物之间的高度分歧。种内的分歧如此之高，以至于达到了种间分歧的水平。此外，在这些LRR区域中还鉴定出了频繁的移码突变和丰富的基因转换事件。
我们的研究结果表明，这个家族具有异常高的遗传丰度水平，这使其特别引人关注。与其他已报道的例子一起，我们的研究还提供了证据，证明多抗性是像这样的R基因家族的一个共同特征。
