Genetic analysis has shown that three recessive genes d (dwarf),e (enlarged trunk) and f (fine leaf) are all found on chromosome #1of apple. When a plant that was heterozygous for each of thesemarkers was testcrossed, the following 1000 progenies wereobtained:
wild type- 130 (+++)
fine leaf- 19 (++f)
enlarged trunk- 2 (+e+)
enlarged trunk, fine leaf – 350 (+ef)
dwarf -362 (d++)
dwarf, fine leaf -1 (d+f)
dwarf, enlarged trunk -16 (de+)
dwarf, enlarged trunk, fine leaf- 120 (def)
a) Determine the central gene.
b) Calculate recombination frequencies between each of thesethree pairs of genes.
c) Draw a genetic map for the location of these 3 genes onchromosome #1 of apple. Show the map distances (cM or m.u.) betweeneach loci.
d) Determine the interference among crossover events within theregion of the chromosome containing the three genes.
