Evolutionary History and Complementary Selective Relaxation of the Duplicated PI Genes in Grasses

作     者：Ruo-Xun Wei Song Ge 

作者机构：State Key Laboratory of Systematic and Evolutionary Botany Institute of Botany the Chinese Academy of Sciences Beijing 100093 China Graduate University of the Chinese Academy of Sciences Beijing 100049 China 

出 版 物：《Journal of Integrative Plant Biology》 (植物学报（英文版）)

年 卷 期：2011年第53卷第8期

页      面：682-693页

核心收录：

学科分类：0710[理学-生物学] 071001[理学-植物学] 0907[农学-林学] 07[理学] 08[工学] 0829[工学-林业工程] 09[农学] 

基　　金：supported by the National Natural Science Foundation of China(30990242 and 30121003) the State Key Basic Research and Development Plant of China(9732007CB815704) 

主　　题：evolution selective relaxation duplication PI genes grasses. 

摘      要：Gene duplication plays an important role in the evolution of organisms by allowing functional innovation and the divergence of duplicate genes. Previous studies found two PI-like genes in grass species, sug- gesting functional divergence between the paralogous copies. Here, we reconstructed the evolutionary history of two PI genes from major lineages of grasses and other monocot species, and demonstrated that two PI genes （PI1 and PI2） arose from a whole genome duplication that occurred in a common ancestor of extant grasses. Molecular evolutionary analyses at the family and tribal levels found strong purifying selection acting on two genes in grasses, consistent with the conserved class B function of the PI genes. Importantly, we detected different patterns of selective relaxation between the duplicated PI genes although no signature of positive selection was found. Likelihood ratio tests revealed that the ω ratio for M domain is significantly higher in PI1 than in PI2 but that for K domain is significantly higher in PI2 than in PI1. These findings imply that complementary selective relaxation occurs in two PI genes after duplication, and provide additional molecular evidence for the subfunctionalization of the duplicated PI genes in grasses.