Effective homologous pairing behavior of a tetrasomic chromosome segment in an unusual B-A rearrangement constitution in maize

Abstract

An unexpected nondisjunction event from a cross which involved a BA reciprocal translocation hyperploid as male parent gave rise to a plant which carried two copies of the B10 chromosome in addition to two normal chromosomes 10. An element normally thought to be necessary for a nondisjunction event was apparently lacking. The frequency, in microsporocytes from this plant, of pairing which is effective for crossing over in the chromosome segment present in quadruplicate approached random expectation, suggesting that there is little or no pairing advantage for chromosomes which match throughout theirt length. High overall apparent chiasma frequency in quadrivalents lends support to earlier reports that presence of B chromosome material tends to enhance effective pairing capacity. © 1985 Taylor & Francis Group, LLC.