Kerr, E. A., J. W. Potter and
Z. A. Patrick Linkage
relations of Cf-2 and Mi.
Langford (Can. J. Res. C, 15:108-128,
1937) reported that Cf-2 - the Vetomold
type of resistance to Cladosporium
fulvum - was linked with c at a distance
of 43 crossover units.
His data also show 43.1 units between Cf-2-and j. Gilbert (TGC 8:15-17,
1958) has shown that nematode resistance Mi is about 2 units from yv and
about 40 units from c. From these data it has been assumed that Cf-2 and
Mi are near each other on chromosome 6.
In 1962 we began a minor but continual experiment to combine these
economically desirable genes into one stock by growing up to 48 populations
twice a year. In the spring crop of 1972 we succeeded in getting a line that
was homozygous resistant for Cf-2. The following season a line homozygous
for both resistances was obtained. Small backcross populations with rvt and
c were produced. Those that could be reliably scored for Cf-2 and Mi gave
the results shown in the table.