Genome-wide identification and expression analysis of MYB gene family in oil palm (Elaeis guineensis Jacq.) under abiotic stress conditions

The MYB transcription factors are one of the largest gene families in plants and known to play critical roles in regulating various responses including abiotic stresses. Currently, a few of MYB family genes have been identified and characterized in various plants. In this study, we identified a set of 159 MYB genes in oil palm via genome-wide screening. The 159 identified oil palm MYB genes belong to two subfamilies (R2R3-MYB and 3R-MYB type), and were divided into 25 subgroups based on phylogenetic analysis. These EgMYB genes were mapped on the 16 chromosomes of the oil palm genome with the co-linearity relationship among them. The intron/exon organization and motif compositions were conserved among the EgMYB genes. Gene duplication analysis also proved that EgMYB genes experienced strong purifying selection and tandem duplications during evolution. Expression profile analysis revealed the constitutive expression of EgMYB genes in different tissues of oil palm. Quantitative PCR analysis of 21 EgMYB genes under different abiotic stress conditions (cold, salt, and drought) proved their differential expression. A total of 20, 19, and 18 EgMYB genes were significantly up-regulated under cold, salt, and drought stress conditions respectively. In addition, none of the analyzed EgMYB genes were down-regulated under any of these stress conditions. Our study elucidated the role of EgMYB genes in abiotic stress conditions and can be used as prominent candidate genes for improving abiotic stress tolerance in this important oil yielding crop.