Analysis of EST sequences suggests recent origin of allotetraploid colonial and creeping bentgrasses

Advances in plant genomics have permitted the analysis of several members of the grass family, including the major domesticated species, and provided new insights into the evolution of the major crops on earth. Two members, colonial bentgrass (Agrostis capillaris L.) and creeping bentgrass (A. stolonifera L.) have only recently been domesticated and provide an interesting case of polyploidy and comparison to crops that have undergone human selection for thousands of years. As an initial step of characterizing these genomes, we have sampled roughly 10% of their gene content, thereby also serving as a starting point for the construction of their physical and genetic maps. Sampling mRNA from plants subjected to environmental stress showed a remarkable increase in transcription of transposable elements. Both colonial and creeping bentgrass are allotetraploids and are considered to have one genome in common, designated the A2 genome. Analysis of conserved genes present among the ESTs suggests the colonial and creeping bentgrass A2 genomes diverged from a common ancestor approximately 2.2 million years ago (MYA), thereby providing an enhanced evolutionary zoom in respect to the origin of maize, which formed 4.8 MYA, and tetraploid wheat, which formed only 0.5 MYA and is the progenitor of domesticated hexaploid wheat.