Cucurbit Genetics Cooperative Report 1:12 (article 10) 1978
Gene Linkage in the 'Lemon' Cucumber
R. W. Robinson
New York Agricultural Experiment Station, Geneva, NY 14456
The 'Lemon' cucumber is an interesting novelty. Named after its round, yellow fruit, it was apparently introduced in the early 1890's. The slight resemblance of its fruit to a citrus gave a rise to an ingenious prevarication in the year 1909. A huckster announced that he had plucked an orange blossom from his daughter's bridal bouquet and used it to pollinate a cucumber plant. The result of this bizarre union was, he claimed, a cucumber plant with fruit like an orange. He offered to sell seed of this marvelous creation for the not inconsiderable sum of a dollar per seed. It was, of course, not an interfamilial cross, but rather high priced seed of the 'Lemon' cucumber.
The 'Lemon' cucumber is still grown today by home gardeners, not only for its novelty value but also for its lack of bitterness and its sweet taste. In my refractometer tests of fruit soluble solids, 'Lemon' was higher than all other cultivars.
The 'Lemon' cucumber was introduced to Russia from the U.S. There it was considered so distinctive that it was classified as a new species, Cucumis sphaerocarpus. However, the relatively few genes that distinguish 'Lemon' from other cucumbers, and the complete fertility of crosses between 'Lemon' and other cucumbers, leaves no doubt but that 'Lemon' is a cultivar of Cucumis sativus.
A surprisingly large number of the characters that distinguish 'Lemon' are linked on the same chromosome. Linkage was evident in the F2 of 'Lemon' x 'Ashley' for genes governing sex expression (m), fruit locule number (l), leaf position (alternate vs. opposite at lower nodes of the main stem), fruit position (on main stem and laterals vs. only on laterals), fruit spine size and number (fine and many vs. coarse and few), fruit shape (round vs. elongated), fruit striping, and ovary shape (pr). Monogenic Mendelian ratios were obtained for m, l, pr, spine size and number, fruit shape, and fruit striping, but not for the other characters of this linkage complex. B, yg, and genes for powdery mildew tolerance segregated independently of this linkage group and of each other.
Complete linkage was noted for m, pr, fruit shape, and spine size and number. It is likely that some or all of these characters are due to the same pleiotropic gene. Crossover types were observed between m and the other linked characters, but pleiotropy cannot be excluded because of the possibility of incomplete penetrance or misclassification. Not all associations were due to pleiotropy, however, and the l locus appears to be distinct from but linked to the m locus.
Pleiotropy would, in part, explain the occurrence of multiple linked factors in 'Lemon'. It is unresolved, however, why so many genes not present in other cucumber cultivars, some linked and others independent, should accumulate in the 'Lemon' cucumber. I would appreciate receiving any information on the origin of the 'Lemon' cultivar.