CHROMOSOMAL INTERCHANGES IN 6 HEXAPLOID OAT GENOTYPES

Intercultivar chromosomal interchanges in oat, 2n = 6x = 42, Avena sativa L., have not been extensively investigated. The objective of this research was to determine the occurrence of chromosomal interchanges among several cultivars of spring oat. Five oat cultivars (Andrew, Gopher, Hazel, Ogle, Otee) and experimental breeding line (PA12422) included in this study carried expected 2n = 6x = 42 chromosomes, showed diploidlike meiosis with 21II and set normal seeds. All the intercultivar F1 hybrids were vigorous and completely pollen- and seed-fertile. Meiotic chromosome pairing at diakinesis of F1 hybrids revealed the following information: (i) Gopher and Otee contain similar chromosome structures and are differentiated from Andrew by a single chromosomal interchange; (ii) Hazel and Ogle possess identical chromosome structure and differ from Gopher and Otee by a single chromosomal interchange and by double interchanges from Andrew; and (iii) breeding line PA12422 differs from Hazel and Ogle by two different interchanges, but the two interchanges involve the same chromosome giving a 1V1 + 18II chromosome configuration. Thus, multivalents occurred frequently in the hexaploid spring oat F1 hybrids studied.