Homeology Between the Chromosomes of Avena macrostachya and the Avena C Genome

To gain more information about the widely unknown genome constitution of the taxonomically and agronomically interesting wild oat Avena macrostachya, this tetraploid species was crossed (as the pollinator) with several diploid Avena species. Hybridization failed with A. strigosa (A_s A_s), A. hirtula (A_s A_s), and A. longiglumis (A₁ A₁), but succeeded with A. atlantica (A_s A_s), A. prostrata (A_p A_p), and A. pilosa (C_p C_p). The output of hybrids and the vitality of the F: plants were highest in the combination A. pilosa×A. macrostachya. Hybrids from this cross relatively frequently showed trivalents at metaphase I as compared to the nearly consistent formation of seven univalents and seven bivalents in hybrids with the A genome species A. atlantica and A. prostrata. Altogether, the results confirm an auto-ploid origin of A. macrostachya and demonstrate that among the two known basic genomes A and C of the genus Avena only the latter exhibits considerable homeology to the A. macrostachya genome.