Comparative transcriptome and tolerance mechanism analysis in the two contrasting wheat (Triticum aestivum L.) cultivars in response to drought and salinity stresses

Drought and salinity are the two important and commonly co-occurring abiotic stresses affecting plant growth and productivity worldwide. Here, we compared the genome-wide transcriptome in the two contrasting wheat cultivars (JM22, drought/salt tolerant; YM20, salt sensitive) in response to drought (10% soil moisture) and salinity (100 mM NaCl) stresses. A total of 295 and 94 genes were characterized as drought and salinity responsive according to their different expression profile between JM22 and YM20 in response to drought and salinity stresses, respectively. Of these, 193 and 67 genes, up-regulated in JM22 while down-regulated/unchanged in YM20 and 103 and 27 genes unchanged in JM22 but down-regulated in YM20, under drought and salinity, respectively. Functional enrichment analysis showed that, JM22 recorded higher expression for genes related to ROS detoxification and defense, in response to drought (e.g. phenolic glucosidemalonyltransferase and anthocyanidin 5,3-O-glucosyltransferase-like) and salinity (flavonoid 3′-monooxygenase and heat shock 70 kDa protein). Meanwhile, genes encoding phytohormone and signal transduction (e.g. cytokinin, LRR receptor kinase and LRK14) were prominently up-regulated in JM22 under drought. F-type H+/Na+-transporting ATPase subunit beta, and Ca2+ signal transduction sensors and key regulatory genes responsible, including zinc finger, NAC and WRKY were showed higher expression in JM22 in salinity stress. Further analysis of genotypic difference in transcriptome in response to drought and salinity, we identified 10 DEGs, annotated to cellular process, metabolic process, osmotic regulation, and MAPK signaling pathway, being co-identified as drought and salinity tolerance associated DEGs. Our results suggest that the co-expression of these genes was important for tolerating and adapting to drought and salinity stresses in JM22. This finding increases our knowledge and understanding of the wheat drought and salinity tolerance mechanism and provides molecular bases in breeding potential under drought and salinity stresses.