Genome Wide Identification and Analysis of the R2R3-MYB Transcription Factor Gene Family in the Mangrove Avicennia marina

Drought and salinity stress have become the major factors for crop yield loss in recent years. Drastically changing climatic conditions will only add to the adverse effects of such abiotic stresses in the future. Hence, it is necessary to conduct extensive research to elucidate the molecular mechanisms that regulate plants’ response to abiotic stress. Halophytes are plants that can grow in conditions of high salinity and are naturally resistant to a number of abiotic stresses. Avicennia marina is one such halophyte, which grows in tropical regions of the world in areas of high salinity. In this study, we have analysed the role of R2R3-MYB transcription factor gene family in response abiotic stress, as a number of transcription factors have been reported to have a definite role in stress manifestation. We identified 185 R2R3 MYB genes at genome-wide level in A. marina and classified them based on the presence of conserved motifs in the protein sequences. Cis-regulatory elements (CREs) present in the promoter region of these genes were analysed to identify stress responsive elements. Comparative homology with genes from other plants provided an insight into the evolutionary changes in the A. marina R2R3 MYB genes. In silico expression analysis revealed 34 AmR2R3 MYB genes that were differentially regulated in the leaves and root tissue of A. marina subjected to drought and salinity stress. This study is the first report of the R2R3 MYB gene family in the A. marina genome and will help in selecting candidates for further functional characterisation.