Meiotic irregularities in hexaploid oats: II. A cytological survey of the variety Picton

Abstract

SUMMARY: 1. Picton, a winter-hardy variety of oats selected from the cross Argentine x Grey Winter, contains plants which have irregular meiotic divisions.2. Two types of irregularities were observed: first, univalents and the products of their division; and secondly, bridges and fragments at both first and second divisions.3. Plants selected for a low frequency of irregularities produced offspring with a low frequency of irregular divisions. On the other hand, plants with regular divisions were also obtained from parents which had a high frequency of irregularities.4. It is pointed out that the genetical effects of bridge chromatid formation and breakage is the production of gametes deficient for chromosome segments. There is some evidence that chlorotic plants are produced when such deficiencies become homozygous.5. It is suggested that the meiotic irregularities produce a certain degree of heterozygosity which may make Picton more adaptable, and at the same time give it a certain degree of hybrid vigour.