Meiotic behavior in progeny of tissue culture regenerated oat plants (Avena sativa L.) carrying near-telocentric chromosomes

Abstract

Meiotic behavior was analyzed in 69 progeny of two regenerated oat plants (Avena sativa L.) containing different heteromorphic pairs of chromosomes to evaluate the behavior of the altered chromosomes in succeeding generations after regeneration from tissue culture. Heteromorphic bivalents separated prematurely and lagged during anaphase I in about 9% of the cells. Univalents often divided equationally during the first division, were usually not included in the telophase nuclei during the second meiotic division, and ultimately resulted in micronuclei at the quartet stage. Heteromorphic pairs were found in some progeny plants that behaved either more stably or less stably than the progenitor heteromorphic pairs. These variants may have been due to changes in the deficient chromosomes, which possibly arose from bridges during the previous meiosis. Higher than normal frequencies of bridges were seen at anaphase I in microsporocytes of plants containing heteromorphic pairs. Meiotic behavior of heteromorphic pairs involving a SAT chromosome was compared with that of the respective monosome that had been recovered in progeny of a plant carrying the heteromorphic pair. Quartet micronuclei frequencies indicated that chromosomes from the heteromorphic bivalent were included in microspores at a much higher rate than was the respective monosome. Key words: meiotic behavior, heteromorphic chromosome pair, oats, tissue culture, telocentric chromosomes, variation.