Genome-wide identification of the R2R3-MYB gene family in olive and its association with fatty acid biosynthesis.

MYB transcription factors play an important role in the biosynthesis of fatty acids in plants. Olive (Olea europaea L.) is one of the woody plants that has been used the longest for the production of oil. However, their functions in fatty acid metabolism of Olive fruit is not well defined. This study identified 212 OLR2R3 MYB genes from the olive genome, which were unevenly distributed across 23 chromosomes. A phylogenetic analysis revealed that they are clustered into six subgroups, and the OLR2R3 MYB gene members in different subgroups have similar gene structures and conserved motifs. A collinearity analysis revealed 17 pairs of segmentally duplicated OLR2R3 MYB genes. The levels of expression of each OLR2R3 MYB gene in the fruit, flower, and bud tissues from various varieties of olive were analyzed. This revealed that 50 genes may be involved in the development of olive fruit. A co-expression network analysis showed that OLMYB185 is co-expressed with the genes for the biosynthesis of fatty acids. The overexpression of OLMYB185 in Arabidopsis seeds significantly increased the seed size compared to the wild type. These results further elucidate the role of OLR2R3 MYB in the biosynthesis of fatty acids in olive fruit and provide new insights into the function of these genes in olive plants.