Epistasis analysis: map distances from tetrad analysis

Map distance (cM)
RM97Wild type38.323.139.861.222.254.0
RM99 msh4 12.84.513.214.69.825.5
RM98 zip1 7.97.911.825.512.630.8
RM1000 zip1 msh4

For each interval, 80–100 tetrads containing four viable spores were analyzed. The exception is the HIS3ADE2 interval in strains RM97 and RM98, for which 63 and 78 tetrads were analyzed, respectively. Recombination frequencies for msh4 and zip1 are significantly different (P < 0.05) from those in wild type, except for the HOM3TRP2 interval in the zip1 mutant (P = 0.126). In no case is the recombination frequency in the msh4 zip1 double mutant significantly different from that in the msh4 or zip1 single mutant.