STUDIES ON THE RELATIONSHIP OFAVENA SATIVA(6x) ANDAVENA HIRTULA(2x)

Abstract

Chromosome pairing in the 8x amphiploid between Avena hirtula and A sativa shows a lower frequency of multivalents than that expected based on accepted genomic designation. In the 1st back-cross hybrids to A sativa the observed pairing was 21II + 7I. The results are discussed in relation to differential affinity between the chromosomes of the common A.genome of A hirtula and A sativa and also to the possibility of the presence of a genetic system controlling regular bivalent pairing in A sativa. The amphiploid plants and the back-cross hybrids were morphologically similar, the hirtula genes being expressed in both homozygous and hemizygous condition. The mean fertility of both the amphiploid plants and the BC1 hybrids was 85%, however, the variation in chromosome number in later generations of the amphiploids would make plant breeding at this level of ploidy impracticable unless more complete chromosome pairing could be achieved.