Inheritance of a New Trait—Twin Fused Fruit—in Cucumber

Abstract

A new trait, twin fused fruit, was discovered in gynoecious cucumber (Cucumis sativus L.) line B 5263. Plants with the twin fused fruit trait had two fruit fused into a single unit. In addition to having the twin fused fruit trait, line B 5263 had fruit with necks, large tubercles (warts), and dark green skin. The inheritance of twin fused fruit was studied in populations resulting from crosses between gynoecious line B 5263 (twin fused fruit) and monoecious line B 5404 (single fruit). Research was done in 1999 to 2001 in the greenhouses of the Research Institute of Vegetable Crops, Skierniewice, Poland. The F1 progeny developed single fruit in all cases. The observed distribution of plant phenotypes in the F2 fitted the expected ratio of 3 with single fruit: 1 with twin fused fruit. The observed distribution of plant phenotypes in the BC1A fitted the expected ratio of 1 with single fruit: 1 with twin fused fruit. Twin fused fruit occurred only in gynoecious plants, and never in monoecious plants of the cross. In the F2 progeny, the ratio of twin fused fruit within gynoecious plants fitted the expected ratio but the gene was not expressed in monoecious plants. In the F2 generation, the observed distribution of plant phenotypes fitted the expected ratio of 9 gynoecious single: 4 monoecious single: 3 gynoecious twin fused: 0 monoecious twin fused, indicating that there was epistasis, with twin fused fruit hypostatic to monoecious. The new gene will be named tf (twin fused fruit).