NaCl stress-induced transcriptomics analysis of Salix linearistipularis (syn. Salix mongolica)

Abstract

Background

Salix linearistipularis (syn. S. mongolica) is a woody halophyte, which is distributed naturally in saline-alkali soil of Songnen plain, Heilongjiang, China. It plays an important role in maintaining ecological balance and in improving saline soil. Furthermore, S. linearistipularis is also a genetic resource; however, there is no available information of genomic background for salt tolerance mechanism. We conducted the transcriptome analysis of S. linearistipularis to understand the mechanisms of salt tolerance by using RNA-seq technology.

Results

The transcription profiles of both the salt stress (SLH-treated) and the control (SLH-control) sample for S. linearistipularis were obtained by using RNA-seq in this study. By comparative analysis, only 3034 of 53,362 all-unigenes between two samples were expressed differently at more than 1.5-fold ( \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\left| {fold - change} \right| \ge 1.5$$\end{document} , FDR ≤ 0.05), including 1397 up-regulated genes and 1637 down-regulated genes. In total, 2199 genes were classified into 50 Gene Ontology (GO) terms and 1103 genes were involved in 116 biological pathways. To find salt stress related genes, all-unigenes of S. linearistipularis were classified into three categories according to their degree of the differentially expressed genes (DEGs) at 0–1.5-fold (non differently expressed genes, N-DEGs), at 1.5–4.0-fold and more than 4.0-fold. The pathways of three categorized genes were compared with the DEGs of Arabidopsis thaliana, showing that 22, 10 and 1 pathway of S. linearistipularis were overlapped with A. thaliana. Degree of the overlapping was categorized as 0–1.5-fold, 1.5–4.0-fold and more than 4.0-folds.

Conclusion

Our study revealed that the N-DEGs of 22 pathways in S. linearistipularis were overlapped with the DEGs of A. thaliana. This result suggests that those overlapped genes that contrasted with the up- or down-regulated genes in A. thaliana were possibility evolved into housekeeping genes in S. linearistipularis under salt stress.

Electronic supplementary material

The online version of this article (doi:10.1186/s40709-016-0038-7) contains supplementary material, which is available to authorized users.