Positive Selection and Functional Divergence of R2R3-MYB Paralogous Genes Expressed in Inflorescence Buds of Scutellaria Species (Labiatae)

International Journal of Molecular Sciences

Bing-Hong Huang³  Erli Pang¹  Yi-Wen Chen²  Huifen Cao¹  Yu Ruan⁴  Pei-Chun Liao³ 

[1] Laboratory of Computational Molecular Biology, College of Life Sciences, Beijing Normal University, Beijing 100875, China; E-Mails:;Department of Biological Science and Technology, National Pingtung University of Science and Technology, 1, Shuefu Rd., Neipu, Pingtung 912, Taiwan; E-Mail:;Department of Life Science, National Taiwan Normal University, 88, Ting-Chow Rd., Sec. 4, Taipei 116, Taiwan; E-Mail:;School of Life Science and Engineering, Chongqing Three Gorges University, Chongqing 404001, China; E-Mail:

关键词: anthocyanin;    evolutionary rate;    functional divergence;    phylogenetic analysis;    positive selection;    R2R3-MYB;    Scutellaria;   

DOI  :  10.3390/ijms16035900

来源: mdpi

【 摘 要 】

Anthocyanin is the main pigment forming floral diversity. Several transcription factors that regulate the expression of anthocyanin biosynthetic genes belong to the R2R3-MYB family. Here we examined the transcriptomes of inflorescence buds of Scutellaria species (skullcaps), identified the expression R2R3-MYBs, and detected the genetic signatures of positive selection for adaptive divergence across the rapidly evolving skullcaps. In the inflorescence buds, seven R2R3-MYBs were identified. MYB11 and MYB16 were detected to be positively selected. The signature of positive selection on MYB genes indicated that species diversification could be affected by transcriptional regulation, rather than at the translational level. When comparing among the background lineages of Arabidopsis, tomato, rice, and Amborella, heterogeneous evolutionary rates were detected among MYB paralogs, especially between MYB13 and MYB19. Significantly different evolutionary rates were also evidenced by type-I functional divergence between MYB13 and MYB19, and the accelerated evolutionary rates in MYB19, implied the acquisition of novel functions. Another paralogous pair, MYB2/7 and MYB11, revealed significant radical amino acid changes, indicating divergence in the regulation of different anthocyanin-biosynthetic enzymes. Our findings not only showed that Scutellaria R2R3-MYBs are functionally divergent and positively selected, but also indicated the adaptive relevance of regulatory genes in floral diversification.

【 授权许可】

CC BY   
© 2015 by the authors; licensee MDPI, Basel, Switzerland.