IDENTIFICATION OF KEY GENES AND CONSERVED REGULATORY PATHWAYS INVOLVED IN DROUGHT TOLERANCE IN FOUR GRAMINEAE SPECIES THROUGH A TRANSCRIPTOMIC META-ANALYSIS

Drought negatively affects plant growth and development. The ability to tolerate abiotic stresses varies among species, and among genotypes within species. Unrevealing the molecular mechanisms behind drought response is essential to identify the genes involved in tolerance. A meta-analysis on RNA-Seq data of four Gramineae species was performed to identify the genes representing common key players in response to drought, as well as the regulatory pathways in which these genes are involved. Four available RNA-Seq datasets were selected, representing the transcriptomic response to drought in the leaf of two contrasting genotypes (tolerant and sensitive) in brachypodium, barley, maize and rice. We re-analysed the transcriptomic data with a unique pipeline and detected the differentially expressed genes (DEGs) in both genotypes of the four experiments. The drought-induced variation in DEG expression was compared between tolerant and susceptible genotypes of each species. We assumed that the genes whose expression regulation differs between the two contrasting genotypes represent key players in the differentiation between the tolerant and the sensitive response to drought. The putative rice orthologues of the selected genes were identified to obtain comparable datasets. We found 69 common genes that are putatively involved in drought tolerance in the four species, and protein-protein interaction were predicted. The DEGs encoding transcription factors that may play a role in drought tolerance were also identified. Gene co-expression networks were constructed to reveal common regulatory pathways that putatively differentiate the response of tolerant and susceptible genotypes in the four Gramineae species.