Molecular responses of amaranth species to abiotic stresses
Abiotic stress triggered by Drought or soil salinity impacts  negatively on crop production. To better understand amaranth responses to those environmental stresses, transcriptomics approaches were applied to investigate changes at molecular level in leaves of two Amaranthus species: A. hybridus, a wild species that grows in saline soils and A. hypochondriacus, the most cultivated species for grain production. Under control conditions, A. hybridus showed up-regulation of organic hydroxyl and sulfur compound processes, while A. hypochondriacus showed up-regulation of genes related to photosynthetic process, amino acids, fatty acids, and secondary metabolism. Under salt stress, significantly fewer DEGs were observed in A. hybridus, interestingly those were related to phosphonate and phosphinate metabolism, phosphorous mobilization, and steroid biosynthesis. In contrast, A. hypochondriacus response to salt stress was characterized by starch, sucrose, and trehalose metabolism, porphyrin, monoterpenoid and organonitrogen compounds biosynthetic process.Under water deficit, both species showed similar transcriptional response by up-regulation of LEAs, dehydrins, and genes related to the biosynthesis of Raffinose Family Oligosaccharides. A. hypochondriacus better adaptation to grow under drought and salt stress could be due to its fast response observed by the up-regulation of MAPK signaling pathways, ABC transporters, and production of defense compounds such as glucosinolates. The common response in both amaranth species to both type of stresses was observed by modulation of secondary metabolism, which was directed towards cell wall modification, cuticle and wax metabolism, and the production of antimicrobial and antifungal metabolites Overall design: RNAseq of A. hybridus or A. hypochondriacus plants well watered (Control) or subjected to saline (salinity stress) or water stress (drought) were sequenced by triplicate. Differentially expressed genes were obtained from stress vs control treatments in each amaranth species.