Effect of trisomy 6 on recombination in chromosome 9 of maize.

The effect of an additional chromosome 6 upon recombination in chromosome 9 was investigated in maize. Trisomic 6 plants and their disomic sibs, heterozygous for three loci of chromosome 9 (yg, sh and wx), were testcrossed, and recombination in the regions yg-sh and sh-wx was analyzed. Single exchanges in the sh-wx region and double exchanges were more frequent in trisomics, particularly in female flowers.--In reciprocal testcrosses, higher male crossover rates were found for the sh-wx region, and the difference was enhanced in trisomic 6 plants.