Transcriptome profiles identify the common responsive genes to drought stress in two Elymus species.

Elymus, the largest genus of the Triticeae Dumort, is a forage grass in the Qinghai-Tibetan Plateau, where the climate has gradually become increasingly dry in recent years. To understand the mechanisms of the response to drought stress in Elymus species, we first investigated physiological and biochemical responses to polyethylene glycol (PEG-6000) simulated drought stress in two Elymus species, Elymus nutans and Elymus sibiricus, and found that E. nutans was more tolerant to drought stress than E. sibiricus. De novo transcriptome analysis of these two Elymus species treated with or without 10 % PEG-6000 revealed that a total of 1695 unigenes were commonly regulated by drought treatment in these two Elymus species, with 1614 unigenes up-regulated and 81 unigenes down-regulated. The coexpressed differentially expressed genes (DEGs) were enriched in regulation of transcription and gene expression in the GO database. KEGG pathway analysis indicated plant hormone signaling transduction were mostly enriched in co-expressed DEGs. Furthermore, genes annotated in the plant hormone signaling transduction were screened from co-expressed DEGs, and found that abscisic acid plays the major role in the drought stress tolerance of Elymus. Meanwhile, transcription factors screened from co-expressed DEGs were mainly classified into the ERF subfamily and WRKY, DREB, and HSF family members. Our results provide further reference for studying the response mechanism and culturing highly tolerant grasses of the Elymus species under drought stress.