Adjustment of Lateral Element Lengths in Hybrids of Lolium Temulentum x L. Multiflorum

Lateral element lengths and synaptic behaviour of meiotic chromosomes are compared in Lolium temulentum, L. multiflorum and their disomic and trisomic interspecific F1 hybrids. The 45 % difference in nuclear DNA amounts between the parents translates into a 66% difference in lateral element lengths at meiotic prophase. Despite the large length disparities, homoeologues form bivalents at meiotic prophase in the disomic hybrid, which are morphologically and functionally very similar to those of both parents. The relative lengths of the lateral elements of the trivalent of the trisomic hybrid do not conform to expectations. They are longer than expected compared with the rest of the complement, and cannot in many cases be identified as belonging to L. temulentum or L. multiflorum. The possible reasons for this anomaly are considered.