title: Identification of 4CL Genes in Desert Poplars and Their Changes in Expression in Response to Salt Stress.
abstract: 4-Coumarate:CoA ligase (4CL) genes are critical for the biosynthesis of plant phenylpropanoids. Here we identified 20 4CL genes in the genomes of two desert poplars (Populus euphratica and P. pruinosa) and salt-sensitive congener (P. trichocarpa), but 12 in Salix suchowensis (Salix willow). Phylogenetic analyses clustered all Salicaceae 4CL genes into two clades, and one of them (corresponding to the 4CL-like clade from Arabidopsis) showed signals of adaptive evolution, with more genes retained in Populus than Salix and Arabidopsis. We also found that 4CL12 (in 4CL-like clade) showed positive selection along the two desert poplar lineages. Transcriptional profiling analyses indicated that the expression of 4CL2, 4CL11, and 4CL12 changed significantly in one or both desert poplars in response to salt stress compared to that of in P. trichocarpa. Our results suggest that the evolution of the 4CL genes may have contributed to the development of salt tolerance in the two desert poplars.
authors.affiliation: State Key Laboratory of Grassland Agro-Ecosystem, School of Life Sciences, Lanzhou University, No.222, Tianshui Southern Road, Lanzhou 730000, China. chzhang13@lzu.edu.cn.
authors.forename: Cai-Hua
authors.initials: CH
authors.lastname: Zhang
authors.affiliation: State Key Laboratory of Grassland Agro-Ecosystem, School of Life Sciences, Lanzhou University, No.222, Tianshui Southern Road, Lanzhou 730000, China. matao.yz@gmail.com.
authors.forename: Tao
authors.initials: T
authors.lastname: Ma
authors.affiliation: State Key Laboratory of Grassland Agro-Ecosystem, School of Life Sciences, Lanzhou University, No.222, Tianshui Southern Road, Lanzhou 730000, China. wchluo2011@gmail.com.
authors.forename: Wen-Chun
authors.initials: WC
authors.lastname: Luo
authors.affiliation: State Key Laboratory of Grassland Agro-Ecosystem, School of Life Sciences, Lanzhou University, No.222, Tianshui Southern Road, Lanzhou 730000, China. xujianmei131412@126.com.
authors.forename: Jian-Mei
authors.initials: JM
authors.lastname: Xu
authors.affiliation: State Key Laboratory of Grassland Agro-Ecosystem, School of Life Sciences, Lanzhou University, No.222, Tianshui Southern Road, Lanzhou 730000, China. liujq@lzu.edu.cn.
authors.forename: Jian-Quan
authors.initials: JQ
authors.lastname: Liu
authors.affiliation: State Key Laboratory of Grassland Agro-Ecosystem, School of Life Sciences, Lanzhou University, No.222, Tianshui Southern Road, Lanzhou 730000, China. wandsh@lzu.edu.cn.
authors.forename: Dong-Shi
authors.initials: DS
authors.lastname: Wan
keywords: 4CL gene family; adaptive evolution; desert poplars; expression divergence; salt stress