De novo Transcriptome Analysis in Leymus mollis to Unveil Genes Involved in Salt Stress Response

Leymus mollis,a wild relative of wheat,is very tolerant to salt stress,and has been considered as a valuable genetic resource for wheat breeding.However,the genetic basis for salt tolerance of this species is still largely unknown.In this study,de novo sequencing,assembly and analysis of L.mollis transcriptome in response to salt stress was performed.A total of 110,323 and 112,846 unigenes were generated for the NaCl-free(CK)and 180 mM NaCl-treated(CT)library,respectively.For the two libraries,73,414 unigenes were successfully annotated in five common protein databases,and 7521 differentially expressed genes(DEGs)between CK and CT libraries were identified.GO enrichment analysis of the DEGs showed that the significantly enriched GO terms were predominantly involved in environmental adaptation(including“response to abiotic stimulus”,“response to water deprivation”),regulation of signaling pathway(such as“regulation of abscisic acid mediated signaling pathway”,“regulation of cell communication”),and photosynthesis(including“response to light stimulus”,“photosynthesis,light harvesting”and“chlorophyll metabolic process”).KEGG pathway enrichment analysis showed that“mRNA surveillance pathway”,“RNA transport”and“plant hormone signal transduction”were predominantly enriched pathways,followed by several secondary metabolic pathways,photosynthesis,carbohydrate metabolism and lipid metabolism.In addition,DEGs related to osmotic stress,ion homeostasis and oxidative stress,including four dehydrins,five aquaporins,an LmNHX2 and several antioxidant enzymes or proteins genes,were found to be up-regulated in response to salt stress.These results will be helpful for further studies on the molecular mechanisms of salt responses in L.mollis.