2-GENE INTERACTION AND LINKAGE FOR BITTERFREE FOLIAGE IN CUCUMBER

A second gene for bitterfree foliage in cucumber (Cucumis sativus L.) was discovered. In a cross between two inbred lines having bitterfree foliage (NCG-093 and WI 2757), the F-1 progeny were bitter, the F-2 pr ogeny segregation frequency fit a ratio of 9 bitter : 7 bitterfree, an d the BC1 segregation frequencies fit a ratio of I bitter : 1 bitterfr ee. Thus, a second factor nonallelic to the previous bitterfree gene, bi, controls the bitterfree trait. When F-2 and BC1 progeny resulting from crosses of bitterfree NCG-093 with other bitter lines were studie d, the second factor for bitterfree in NCG-093 fit a recessive, single -gene model. The existence of a second, recessive bitterfree gene was confirmed in additional crosses, and the gene was designated bi-2. Fur ther analysis of two crosses indicated that bi-2 was linked with the s hort petiole (sp) gene (map distance = 11 cM).