| Soybean (Glycine max) has undergone several rounds of polyploidization and subsequent diploidization. Thus, the present day genome is a paleopolyploid mosaic of homeologous regions derived from whole genome duplications. To reveal the impact of these evolution events on the structure and function of homeologous regions, structural and functional analyses were done for two ∼1mb euchromatic homeologous regions of soybean and an orthologous region from common bean (Phaseolus vulgaris). One of the soybean homoelogous regions (Gm15) underwent more severe structural changes (one inversion ∼0.6 mb and two deletions ∼50 kb and ∼150 kb), more extensive gene movement, and biased accumulation and deletion of LTR retrotransposons. Functional analyses of the two soybean homeologous regions revealed decreases in gene expression and biases in synonymous substitution rates for the same homeologous region. Subfunctionalization of homeologs after duplication was also analyzed by looking at divergent expression patterns among different tissues and developmental stages. Our results indicate asymmetric evolution between homeologous regions after duplication via structural changes and functional changes in gene activity. |
