TRANSLOCATIONS IN LINKAGE MAPPING AND QTL ANALYSIS

¹ Dept. of Agronomy, Univ. of Wisconsin, Madison, WI

² Agriculture Canada, Saskatoon, SK

³ Dept. of Botany, Univ. of Cambridge, UK

Reciprocal translocations can occur as the result of pairing and recombination between homoeologous chromosome regions, and they can subsequently become fixed in sub-populations of a species. In Brassica napus (n=19), the amphidiploid species of B. oleracea (n=9) and B. rapa (n=10), a reciprocal translocation between linkage groups N7 and N16 has been found in several spring oilseed rape cultivars. The translocation was discovered in doubled haploid progenies derived from crosses of winter and spring oilseed rape cultivars which had aberrant segregation of RFLP markers on N7 and N16. Results from cytogenetic analyses of meioses in spring – winter F1 hybrids also provide evidence for the translocation. Segregation of the translocation was significantly associated with variation in seed yield in populations of doubled haploid lines and inbred backcross lines derived from different spring – winter crosses. The highest yields were associated with the balanced configuration of the translocation, providing evidence for the importance of intergenome heterozygosity in contributing to seed yield.