Parallel Domestication, Convergent Evolution and Duplicated Gene Recruitment in Allopolyploid Cotton

A putative advantage of allopolyploidy is the possibility of differential selection of duplicated (homoeologous) genes originating from two different progenitor genomes. In this note we explore this hypothesis using a high-throughput, SNP-specific microarray technology applied to seed trichomes (cotton) harvested from three developmental time-points in wild and modern accessions of two independently domesticated cotton species, G. hirsutum and G. barbadense. We show that homoeolog expression ratios are dynamic both developmentally and over the several-thousand year period encompassed by domestication and crop improvement, and that domestication increased the modulation of homoeologous gene expression. In both species, D-genome expression was preferentially enhanced under human selection pressure, but for non-overlapping sets of genes for the two independent domestication events. Our data suggest that human selection may have operated on different components of the fiber developmental genetic program in G. hirsutum and G. barbadense, leading to convergent rather than parallel genetic alterations and resulting morphology.

Key Words: Cotton, Domestication, Fiber, Gene expression, Polyploidy

Online ISS 1091-6490
Copyright 2008 by the Genetics Society of America
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