Identification And Evolutionary Analysis Of MYB Gene Family In Flowering Plants

The MYB superfamily of transcription factors are key regulators of plant development and responding to the environment change.The diversity of lifestyles and morphological characteristics is potentially associated with the genomic dynamics of the MYB superfamily.However,a comprehensive phylogenomic analysis of the MYB superfamily across viridiplantae is lacking.In order to gain an in-depth understanding of the role of the MYB gene family on the evolution of plants,especially flowering plants,we performed genome-wide identification and subsequent analysis of the MYB gene family in 437 plant species in 22 categories.The main results were as follows:1.MYB family members identified in 437 species and found that the average number of MYB genes in flowering plants was 6 times higher than in non-flowering plants.In flowering plants,members of the 2R-MYB subfamily were more abundant,while in nonflowering plants,members of the 1R-MYB subfamily were more abundant.Compared with flowering plants,the number of MYB genes in non-flowering plants has a larger coefficient of variation.2.MYB collinear gene pairs within species were identified,and flowering plants were found to possess more MYB collinear gene pairs.The Ka and Ks values of these gene pairs were subsequently calculated,and the distribution of Ks values indicated that most flowering plants had undergone the recent MYB gene doubling,and that there were more gene pairs with Ka/Ks > 1 in flowering plants,indicating that flowering plants generally facing greater environmental selection pressure.In addition,through comparative genomics analysis with fungi,we identified a potential MYB gene that may have undergone a horizontal gene transfer event between plants and fungi.3.A total of 53 plants from 22 categories were selected for neo-/sub-functionalization analysis.Expression data showed that more genes(RPKM > 5)were expressed in roots,stems,leaves and flowers of plants compared to other tissues.Subsequently,we analyzed the co-expression patterns of MYB gene pairs in flowering plants and found the highest number of asymmetrically expressed duplicates.4.Multiple MYB subclades show highly conserved patterns of copy number and synteny across flowering plants,while others are more dynamic and show distinct lineagespecific patterns.As examples of lineage-specific morphological divergence due to MYB subclade dynamics,we hypothesize that gain of subclades OG0000000 and OG0000008 correlates with the emergence of flowering plants.In addition,neo-/sub-functionalization of MYB gene duplicates has contributed to the environmental adaptation and speciesspecific neo-/sub-functionalization has contributed to phenotype divergence in different species.This study is the first to reveal the evolutionary differences of the MYB superfamily between flowering species and non-flowering species from the pan-plant scale,preliminary discussion the evolutionary mechanism of species-specificity and conservation of the MYB gene family,and indicating the role of the MYB family in plant adaptation to the environment and key roles in species phenotypic differentiation.This study provides a certain reference for the evolution of plants,and also provides a data basis for the subsequent construction of a database.