Cucurbit Genetics Cooperative Report 1:11 (article 9) 1978
R. W. Robinson
New York Agricultural Experiment Station, Geneva, NY 14456
The F1 of powdery mildew tolerant ‘Ashley’ x susceptible ‘Lemon’ was susceptible to Sphaerotheca fuliginea. The F2 segregated 193 susceptible; 248 tolerant, in a good agreement (p = .5 -.7) with the 27:37 ratio expected if tolerance were governed by three complementary recessive factors.
The F2 data gave no indication of linkage between genes for tolerance to powdery mildew and B, l, pr, yg, or genes for fasciation, leaf size, leaf arrangement (opposite vs. alternate), fruit position (on main stem and laterals vs. only on laterals), spine size and number, and fruit netting. Significant deviations from contingency expected was obtained between powdery mildew genes and m (p = .02-.05) and fruit striping (p = .01-.02). However, this deviation is attributed to chance, since there was a deficiency, not an excess, of paternal phenotypes. The F2 segregation from the repulsion phase cross was 152 + susceptible: 42 msusceptible: 166 + tolerant: 74 m tolerant and 150 nonstriped susceptible: 42 striped susceptible: 166 nonstriped tolerant: 81 striped tolerant.
Other F2 populations involving ‘Ashley’ as the powdery mildew tolerant parent segregated for a chlorosis that appeared to be related to manganese deficiency. Complete linkage or pleiotropy occurred between the interveinal chlorosis and susceptibility to powdery mildew.