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Progressive Differentiation of Spikelet Types in Relation to Ploidy in the Genus Avena
Author(s) -
Nishiyama I.
Publication year - 1987
Publication title -
plant breeding
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.583
H-Index - 71
eISSN - 1439-0523
pISSN - 0179-9541
DOI - 10.1111/j.1439-0523.1987.tb01158.x
Subject(s) - synapsis , biology , ploidy , meiosis , genetics , chromosome pairing , chromosome , genome , avena , gene , hybrid , loss of heterozygosity , botany , allele
In the study of interspecific and interploidy hybrids of Avena the order of spikelet types in the recessive < dominance sequence was found to be as follows: N 1 (naked type) < C 1,2 (cultivated, type) < W 1,2 (wild type) < S 1,2 (subwild type) < W 3 < S 3 < C 3 < N (1)3 , where superscripts 1, 2 and 3 indicate the spikelet type of diploid, tetraploid and hexaploid species, respectively. Nullisomic studies of hexaploid species showed that chromosome MK‐9 of the 3rd genome controlled multiple alleles W 3 , S 3 and C 3 types, except N (1)3 type, and synapsis of meiotic chromosomes. Its homoeologous chromosomes of the 1st and 2nd genomes appeared to affect the W type (probably introduction of W 1 and W 2 ) as well as meiotic asynapsis. The asynapsis might be induced by deficiency of a synapsis‐gene(s) in a primary hexaploid form or species. The N (1)3 type probably occurred by dominant or epistatic mutation of the W 1 type in A. sativa , and the C 3 type hidden was present. The maintenance of such a heterozygosity system may be mainly due to diploid‐like pairing of chromosomes on the balance between the synaptic and asynaptic gene functions.