title: Transcriptomic analysis reveals importance of ROS and phytohormones in response to short-term salinity stress in Populus tomentosa.
abstract: Populus tomentosa (Chinese white poplar) is well adapted to various extreme environments, and is considered an important species to study the effects of salinity stress on poplar trees. To decipher the mechanism of poplar's rapid response to short-term salinity stress, we firstly detected the changes in H2O2 and hormone, and then profiled the gene expression pattern of 10-week-old seedling roots treated with 200 mM NaCl for 0, 6, 12, and 24 h (h) by RNA-seq on the Illumina-Solexa platform. Physiological determination showed that the significant increase in H2O2 began at 6 h, while that in hormone ABA was at 24 h, under salt stress. Compared with controls (0 h), 3991, 4603, and 4903 genes were up regulated, and 1408, 2206, and 3461 genes were down regulated (adjusted P ≤ 0.05 and |log2Ratio|≥1) at 6, 12, and 24 h time points, respectively. The Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway annotation revealed that the differentially expressed genes (DEGs) were highly enriched in hormone- and reactive oxygen species-related biological processes, including "response to oxidative stress or abiotic stimulus," "peroxidase activity," "regulation of transcription," "hormone synthetic and metabolic process," "hormone signal transduction," "antioxidant activity," and "transcription factor activity." Moreover, K-means clustering demonstrated that DEGs (total RPKM value>12 from four time points) could be categorized into four kinds of expression trends: quick up/down over 6 or 12 h, and slow up/down over 24 h. Of these, DEGs involved in H2O2- and hormone- producing and signal-related genes were further enriched in this analysis, which indicated that the two kinds of small molecules, hormones and H2O2, play pivotal roles in the short-term salt stress response in poplar. This study provides a basis for future studies of the molecular adaptation of poplar and other tree species to salinity stress.
authors.affiliation: State Key Laboratory of Tree Genetics and Breeding, Research Institute of Forestry, Chinese Academy of Forestry Beijing, China.
authors.forename: Lingyu
authors.initials: L
authors.lastname: Zheng
authors.affiliation: College of Landscape and Travel, Agricultural University of Hebei Baoding, China.
authors.forename: Yu
authors.initials: Y
authors.lastname: Meng
authors.affiliation: State Key Laboratory of Tree Genetics and Breeding, Research Institute of Forestry, Chinese Academy of Forestry Beijing, China.
authors.forename: Jing
authors.initials: J
authors.lastname: Ma
authors.affiliation: State Key Laboratory of Tree Genetics and Breeding, Research Institute of Forestry, Chinese Academy of Forestry Beijing, China.
authors.forename: Xiulian
authors.initials: X
authors.lastname: Zhao
authors.affiliation: College of Biology and the Environment, Nanjing Forestry University Nanjing, China.
authors.forename: Tielong
authors.initials: T
authors.lastname: Cheng
authors.affiliation: State Key Laboratory of Tree Genetics and Breeding, Research Institute of Forestry, Chinese Academy of Forestry Beijing, China.
authors.forename: Jing
authors.initials: J
authors.lastname: Ji
authors.affiliation: State Key Laboratory of Tree Genetics and Breeding, Research Institute of Forestry, Chinese Academy of Forestry Beijing, China.
authors.forename: Ermei
authors.initials: E
authors.lastname: Chang
authors.affiliation: Chair of Proteomics and Bioanalytics, Technische Universität München Freising, Germany.
authors.forename: Chen
authors.initials: C
authors.lastname: Meng
authors.affiliation: State Key Laboratory of Tree Genetics and Breeding, Research Institute of Forestry, Chinese Academy of Forestry Beijing, China.
authors.forename: Nan
authors.initials: N
authors.lastname: Deng
authors.affiliation: Institute of Apicultural Research, Chinese Academy of Agricultural Sciences Beijing, China ; Risk Assessment Laboratory for Bee Products, Quality and Safety of Ministry of Agriculture Beijing, China.
authors.forename: Lanzhen
authors.initials: L
authors.lastname: Chen
authors.affiliation: State Key Laboratory of Tree Genetics and Breeding, Research Institute of Forestry, Chinese Academy of Forestry Beijing, China.
authors.forename: Shengqing
authors.initials: S
authors.lastname: Shi
authors.affiliation: State Key Laboratory of Tree Genetics and Breeding, Research Institute of Forestry, Chinese Academy of Forestry Beijing, China.
authors.forename: Zeping
authors.initials: Z
authors.lastname: Jiang
keywords: H2O2; Populus tomentosa; differentially expressed genes; hormone; salt stress; transcriptomic analysis