The relationship between synapsis, recombination nodules and chiasmata in tomato translocation heterozygotes

Abstract

Spreads of synaptonemal complexes (SCs) were made from five different reciprocal translocation heterozygotes in tomato (Lycopersicon esculentum). Patterns of synapsis and distribution of recombination nodules (RNs) and chiasmata were analysed. Translocated chromosomes usually synapsed to form quadrivalents. By measuring the length of synapsed arms, we estimated the positions of the breaks for translocations 2-10b (both breaks in euchromatin), 9-12 (both breaks in heterochromatin), and 2-10a, 1-3 and 1-12 (one break in euchromatin and one break in heterochromatin). The distribution of RNs indicates that interference occurs within arms of quadrivalents. If interference occurs between arms it is transferred to opposite and adjacent arms equally. We found no significant difference between the distribution of RNs and chiasmata. These results support a one RN: one crossover: one chiasma relationship. © 1993 The Genetical Society of Great Britain.