根瘤感受样基因的进化:结构歧异与功能分化  

Evolution of the Nodule Inception-like Genes: Structural Divergence and Functional Differentiation

作　　者：朱新宇[1] 吕万胜[1] 余春梅[1] 汪保华[1] 

机构地区：[1]南通大学生命科学学院,南通226019

出　　处：《植物学报》2013年第5期519-530,共12页Chinese Bulletin of Botany

基　　金：国家自然科学基金(No.31000729);江苏省高校自然科学基金(No.09KJB180006);南通市应用研究计划(No.BK2012062)

摘　　要：豆科植物百脉根(Lotus japonicus)的根瘤感受基因Nin与根瘤的早期发育有关。Nin的同源基因(Nin-like基因)功能上涉及氮代谢过程。从完成测序的豆科和非豆科植物基因组中获取Nin-like基因并进行系统发育分析。在此基础上,追踪基因和蛋白质结构的歧异式样,尝试建立结构歧异和功能分化的联系。通过比较,新的Nin-like基因被鉴别。系统发育分析不仅重现了以前分辨的直系同源群(分支I、II和III),且识别了它们之间的姐妹群关系。Nin-like基因的结构呈现多样性,支持系统发育分析的结果。水稻OsNLP5基因缺乏内含子,可能起源于基因返座事件。NIN-like蛋白结构域组织和功能位点在不同分支中存在差异,提示它们的功能发生了分化。根瘤固氮植物NIN-like蛋白的GAF结构域中存在一个显著变异区,三级建模分析显示这个变异区对应于百脉根非固氮NIN-like蛋白的一段保守构象,这一变异可能使豆科植物具有根瘤固氮能力。研究结果为阐明Nin-like基因的功能提供了新的研究思路。The nodule inception gene Nin is related to early stages of root nodule formation in the model plant Lotus japonicus. Functionally, its homologs, Nin-like genes, are also involved in N metabolism. In this study, Nin-like gene data were retrieved from completely sequencing genomes of legume and non-legume plants for investigating phylogeny to trace the divergence of genes and proteins and build relationships between structural divergence and functional differen- tiation. We revealed novel Nin-like genes; previously resolved orthologous groups were recovered and their sister rela- tionships resolved. Nin-like genes showed a diversity of structures, which supports the results of phylogenetic and func- tional studies; OsNLP5 from Oryza sativa was found to be intronless, which probably originated from a gene retroposition event. We found discrepancies in domain organizations and functional sites among NIN-like proteins, which indicates possible functional differentiation. 3-D structural analysis revealed the occurrence of significant conformational changes in GAF domains of NIN-like proteins from nodule legume plants, which could become the basis of recruitment as nodule inception genes. Our findings will contribute to the design of further experimental studies.

关 键 词：进化 功能分化。Nin—like基因 根瘤共生 结构歧异 

分 类 号：Q943[生物学—植物学]