背景回顾：Nucleotide-binding leucine-rich repeat (NLR) genes comprise the largest family of plant disease resistance genes. Angiosperm NLR genes are phylogenetically divided into the TNL, CNL, and RNL subclasses. NLR copy numbers and subclass composition vary tremendously across angiosperm genomes. 

提出问题：However, the evolutionary associations between genomic NLR content and ecological adaptation, or between NLR content and signal transduction components, are poorly characterized due to limited genome availability.

主要研究：Here, we established an angiosperm NLR atlas (ANNA, https://biobigdata.nju.edu.cn/ANNA/), which includes NLR genes from over 300 angiosperm genomes. 

结果1-NLR基因含量变异：Using ANNA, we revealed that NLR copy numbers differ up to 66-fold among closely related species due to rapid gene loss and gain.

结果2-NLR基因收缩与植物生活方式相关：Interestingly, NLR contraction was associated with adaptations to aquatic, parasitic, and carnivorous lifestyles. The convergent NLR reduction in aquatic plants resembles the lack of NLR expansion during the long-term evolution of green algae before the colonization of land. 

结果3-TNL类丢失与信号转导组分丢失有关：A co-evolutionary pattern between NLR subclasses and plant immune-pathway components was also identified, suggesting that immune pathway deficiencies may drive TNL loss. Finally, we recovered a conserved TNL lineage that may function independently of the EDS1-SAG101-NRG1 module. 

结论：Our findings provide new insights into the evolution of NLR genes in the context of ecological adaptation and genome content variation.

 摘 要 

核苷酸结合富含亮氨酸重复序列（NLR）基因是植物疾病抗性基因的最大基因家族。被子植物的NLR基因从系统发育角度可以分成三个亚支，分别为TNL、CNL和TNL。NLT拷贝数和亚支组成在不同被子植物物种的基因组中变异巨大。但是，由于缺少足够代表性的被子植物基因组，基因组NLR含量和生态适应性或者NLR含量和信号转导组分之间的演化关联还不清楚。本文中，作者收集了300个被子植物基因组，鉴定了其中的NLR基因，建立了被子植物NLR图谱数据库ANNA（网址：https://biobigdata.nju.edu.cn/ANNA/）。利用ANNA，作者发现，由于基因的快速丢失和获得，近缘植物物种之间NLR的数目差异可以达到60倍左右。有趣的是，NLR收缩与适应水生、寄生和肉食性生活方式具有相关性。水生植物趋同的NLR基因数目减少，类似于在陆地定殖之前的长期演化过程中，藻类植物NLR基因从未发生过显著的扩张。作者还鉴定了NLR亚支和植物免疫途径组分之间的协同演化模式，结果表明植物免疫途径的缺陷可能驱动了TNL类NLR基因的丢失。最终，作者揭示了一个保守的TNL支系，独立作用于EDS1-SAG101-NRG1模块。本文的研究为NLR基因在生态适应和基因组含量变异中的演化提供了新的视野。