Two-gene interaction and linkage for bitterfree foliage in cucumber

Abstract

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 W12757), the F1 progeny were bitter, the F2 progeny segregation frequency fit a ratio of 9 bitter: 7 bitterfree, and the BC1 segregation frequencies fit a ratio of 1 bitter: 1 bitterfree. Thus, a second factor nonallelic to the previous bitterfree gene, bi, controls the bitterfree trait. When F2 and BC1 progeny resulting from crosses of bitterfree NCG-093 with other bitter lines were studied, the second factor for bitterfree in NCG093 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. Further analysis of two crosses indicated that bi-2 was linked with the short petiole (sp) gene (map distance = 11 cM).