Origin of the Common Wild Oat, Avena fatua L.

Abstract

IT is generally considered that differentiation of the hexaploid species of oats has resulted primarily from structural changes and gene mutations involving a small group of chromosomes more or less common to all the species. The different species hybridize readily, giving highly fertile progenies, which indicates considerable homology of the chromosomes of any one species with the others. Indeed, it would be difficult to discover a closer chromosome affinity in any group of polyploids than that indicated by Nishiyama¹ for the four hexaploid oat species Avena byzantina, A. fatua, A. sterilis and A. sativa. With complete affinity between any two species represented as 1.000 and no affinity as 0.000, values obtained by Nishiyama from crosses involving the above-mentioned species ranged from 0.983 to 0.998. More recently, however, cytological studies conducted by Joshi and Howard² show that meiotic irregularities are found in fairly high frequencies in hybrids with A. byzantina as one parent, which implies that at least some of the corresponding chromosomes of the various species are not completely homologous.