Transcriptomic and proteomic analyses of drought responsive genes and proteins in Agropyron mongolicum Keng

Agropyron mongolicum Keng is a drought-tolerant perennial forage grass. To elucidate the underlying mechanisms in response to drought stress, we performed transcriptomic and proteomic profiling analyses under mild and severe drought conditions. After de novo assembly, 92,752 unigenes were obtained with an average size of 791 bp and N50 of 1303 bp. 70,732 (76.26%) unigenes showed high sequence similarity with genes in the Nr database. Among the differentially expressed genes, 446 and 418 genes were up- and down-regulated under drought stress, respectively. Using isobaric tags for relative and absolute quantitation technology, we identified 4105 unique proteins. Among them, 255 and 280 proteins were up- and down-regulated, respectively. We selected top 45 genes and proteins that are abundantly expressed yet significantly up- or down-regulated under drought stress. Among the up-regulated genes and proteins, storage proteins and dehydrins dominated the list. Cell wall structural proteins, amylase, and trypsin inhibitors were also up-regulated by drought stress. Chloroplast function-related proteins accounted for the majority of the significantly down-regulated proteins. Pathway analysis indicated that galactose hydrolysis, proline biosynthesis, pentose phosphate pathway and antioxidant systems were significantly up-regulated, whereas pathways of chlorophyll biosynthesis, aromatic amino acid biosynthesis, flavonoid and isoflavonoid biosynthesis were all down-regulated. This study provides both transcriptomic and proteomic profiles in response to drought stress, which are valuable resources for future functional genomics studies in A. mongolicum Keng.