title: Distinct patterns of natural selection in Na+/H+antiporter genes inPopulus euphraticaandPopulus pruinosa.
abstract: Salt tolerance genes constitute an important class of loci in plant genomes. Little is known about the extent to which natural selection in saline environments has acted upon these loci, and what types of nucleotide diversity such selection has given rise to. Here, we surveyed genetic diversity in three types of Na+/H+antiporter gene (SOS,NhaD,andNHX, belonging to the cation/proton antiporter 1 family), which have well-characterized essential roles in plant salt tolerance. Ten Na+/H+antiporter genes and 16 neutral loci randomly selected as controls were sequenced from 17 accessions of two closely related members of the genusPopulus,Populus euphraticaandPopulus pruinosa, sectionTuranga, which are native to northwest China. The results show that salt tolerance genes are common targets of natural selection inP. euphraticaandP. pruinosa.Moreover, the patterns of nucleotide variation across the three types of Na+/H+antiporter gene are distinctly different in these two closely relatedPopulusspecies, and gene flow fromP. pruinosatoP. euphraticais highly restricted. Our results suggest that natural selection played an important role in shaping the current distinct patterns of Na+/H+antiporter genes, resulting in adaptive evolution inP. euphraticaandP. pruinosa.
authors.affiliation: State Key Laboratory of Grassland Agro-Ecosystem School of Life Sciences Lanzhou University Lanzhou Gansu China.
authors.forename: Yuxia
authors.initials: Y
authors.lastname: Wu
authors.affiliation: State Key Laboratory of Grassland Agro-Ecosystem School of Life Sciences Lanzhou University Lanzhou Gansu China.
authors.forename: Kuibin
authors.initials: K
authors.lastname: Meng
authors.affiliation: State Key Laboratory of Grassland Agro-Ecosystem School of Life Sciences Lanzhou University Lanzhou Gansu China.
authors.forename: Xiaohui
authors.initials: X
authors.lastname: Liang
keywords: Na+/H+ antiporter; Populus euphratica; Populus pruinosa; natural selection; nucleotide diversity