Slow evolution of sex‐biased genes in the reproductive tissue of the dioecious plant Salix viminalis

• Published in: Molecular ecology Vol. 27; no. 3; pp. 694 - 708
• Main Authors: Darolti, Iulia, Wright, Alison E., Pucholt, Pascal, Berlin, Sofia, Mank, Judith E.
• Format: Journal Article
• Language: English
• Published: England Blackwell Publishing Ltd 01.02.2018; John Wiley and Sons Inc
• Subjects: Angiosperms; Biological evolution; Codon - genetics; codon usage bias; dioecious angiosperms; Evolution, Molecular; Evolutionary Biology; Evolutionary genetics; Evolutionsbiologi; Gene expression; Gene Expression Regulation, Plant; Genes; Genes, Plant; Molecular evolution; Original; ORIGINAL ARTICLES; Plant Leaves - genetics; Pollen; Reproduction; Salix - anatomy & histology; Salix - genetics; Salix - physiology; Salix viminalis; Selection, Genetic; Sex; Sex Characteristics; sex-biased gene expression; sexual selection; dioecious angiosperms; codon usage bias; sexual selection; sex-biased gene expression
• ISSN: 0962-1083; 1365-294X; 1365-294X
• DOI: 10.1111/mec.14466

The relative rate of evolution for sex‐biased genes has often been used as a measure of the strength of sex‐specific selection. In contrast to studies in a wide variety of animals, far less is known about the molecular evolution of sex‐biased genes in plants, particularly in dioecious angiosperms. Here, we investigate the gene expression patterns and evolution of sex‐biased genes in the dioecious plant Salix viminalis. We observe lower rates of sequence evolution for male‐biased genes expressed in the reproductive tissue compared to unbiased and female‐biased genes. These results could be partially explained by the lower codon usage bias for male‐biased genes leading to elevated rates of synonymous substitutions compared to unbiased genes. However, the stronger haploid selection in the reproductive tissue of plants, together with pollen competition, would also lead to higher levels of purifying selection acting to remove deleterious variation. Future work should focus on the differential evolution of haploid‐ and diploid‐specific genes to understand the selective dynamics acting on these loci.