AUTHOR=Zeng Qiangcheng , Liu Hanyu , Chu Xiaonan , Niu Yonggang , Wang Caili , Markov Gabriel V. , Teng Linhong 

TITLE=Independent Evolution of the MYB Family in Brown Algae

JOURNAL=Frontiers in Genetics

VOLUME=Volume 12 - 2021

YEAR=2022

URL=https://www.frontiersin.org/journals/genetics/articles/10.3389/fgene.2021.811993

DOI=10.3389/fgene.2021.811993

ISSN=1664-8021

ABSTRACT=MYB proteins represent one of the largest families of eucaryotic transcription factors and regulate important processes in growth and development. Studies on MYBs have mainly focused on animal and plants, however, comprehensive analysis across other supergroups, such as SAR is lacking. This study characterized the structure, evolution, and expression of MYBs in four brown algae, which comprise the biggest multicellular lineage of SAR. Subfamily 1R-MYB comprised heterogeneous proteins, with fewer conserved motifs found outside the MYB domain. Unlike SHAQKY subgroup of plant 1R-MYB, THAQKY comprised the largest subgroup of brown algal 1R-MYBs. Unlike the expansion of 2R-MYBs in plants, brown algae harbored more 3R-MYBs than 2R-MYBs. At least ten 2R-MYBs, fifteen 3R-MYBs, and one 6R-MYB orthologs existed in the common ancestor of brown algae. Phylogenetic analysis showed that brown algal MYBs have ancient origin and diverged evolution. They showed strong affinity with stramenopile species, while not with red algae, green algae or animals, suggesting brown algal MYBs did not come from the secondary endosymbiosis of red and green plastids. Sequence comparison among all repeats of the three types of MYB subfamilies revealed that the repeat of 1R-MYBs showed higher sequence identity with R3 of 2R- and 3R-MYBs, which supports the idea that the 1R-MYB was derived from loss of the first and second repeats of the ancestor MYB. Compared with other species of SAR, brown algal MYB proteins exhibited higher proportion of intrinsic disordered regions, which might contribute to multicellular evolution. Expression analysis showed that many MYB genes are responsive to different stress conditions and developmental stages. The evolution and expression analysis provide comprehensive analysis about the phylogeny and functions of MYBs in brown algae.