Cucurbit Genetics Cooperative Report 2:8 (article 4) 1979
A. F. Iezzoni and C. E. Peterson
Department of Horticulture, University of Wisconsin, Madison, WI 53706
Cucumber lines resistant to bacterial wilt caused by Erwinia tracheiphila were established for each of the four sex types (gynoecious, monoecious, hermaphrodite, and andromonoecious) to investigate a possible linkage between the gene for bacterial wilt resistance and the genes controlling sex expression. From the backcross data, a strong linkage was detected between the gene B for bacterial wilt resistance and the gene M for pistillate vs. perfect flowers (Table 1). Similar results were obtained from F2 data from populations in which the M and B alleles were in coupling phase (Table 2). A linkage intensity of .011 ± .0032 was calculated by the product method. Bacterial wilt segregation was consistent with a single monogenic gene as has previously been reported. However, the poor fit of the M / m locus to a 3:1 ratio in the F2 data is unexpected and is being investigated.
Table 1. BC1 data from populations in which the M and B alleles were in coupling phase
Backcross coupling phase |
Mm Bb |
Mm bb |
mm Bb |
mm bb |
Total |
% Recomb |
| MB / mb x mb / mb | 102 | 0 | 0 | 111 | 213 | 0 |
¹M:1m probability 50-60%
¹B:1b probability 50-60%
Table 2. F2 data from populations in which the M and B alleles were in coupling phase.
F2 coupling phase |
M- B- |
M- bb |
mm B- |
mm bb |
Total |
% Recomb |
| MB / mb selfed | 311 | 1 | 10 | 132 | 454 | 1.1±0.32 |
3M:1m probability approx. 0%
3B:1b probability 1-5%