Meiotic pairing control in wheat–rye hybrids. II. Effect of rye genome and rye B-chromosomes and interaction with the wheat genetic system

Several hybrid combinations between rye and wheat ditelosomic for homoeologous group 3 or 5 chromosomes or mutant ph2b were used to analyze the effects of the rye genome and rye B-chromosomes on meiotic pairing. The results indicated that the rye Bs have an effect on bound-arm frequency, which varies with the wheat genotype. If wheat suppressors are absent, pairing decreases when Bs are added; whereas if wheat promoters are lacking, a pairing increase is observed in some hybrids with two rye Bs. There was thus an interaction between the genetic systems of the two parents, with the wheat parent being the main determinant of the pairing level in the hybrids. The rye genome tends to decrease pairing in the absence of wheat suppressors and increase it when wheat promoters are lacking, and the rye Bs tend to reinforce this primary rye action.Key words: Triticum aestivum, Secale cereale, homoeologous pairing, B-chromosomes, promoter–suppressor interaction.