Characterization of the Blunt Leaf Apex (bla) Trait in Cucumber

Abstract

A further characterization of the cucumber (Cucumis sativus L.) mutant `Wisconsin SMR-18' bla (blunt leaf apex) revealed a new character associated with the previously described leaf phenotype. The attachment of the blade to the petiole of bla plants is flat across, as opposed to the cordate or indented attachment in the wild-type `Wisconsin SMR-18' plants. The new character (truncate leaf base) was easier to score and becomes distinctive earlier in development than previously described leaf apex characters. It was expressed consistently in homozygous bla plants. Segregation analysis of 1159 F2 seedlings arising from self-pollinated `Wisconsin SMR-18' × `Wisconsin SMR-18' bla F1 plants suggested that the leaf base and leaf apex character were controlled by a single locus or two tightly linked ones with a maximum distance between the two of 0.03 cM. In a field study of growth and fitness characteristics, the two genotypes did not differ significantly for flower or fruit count. The similar flowering and fruiting characteristics, along with the reliable early occurring truncate character, likely will make the two genotypes useful for pollination and gene movement studies.