The inheritance of gynoecy in muskmelon

Abstract

The gynoecious Cucumis melo (muskmelon) GY-4 (derived from WI-998 after four generations of selfing and selection) was crossed with the monoecious PI124111F or the andromonoecious '36'. The F1 progeny plants from both crosses were all monoecious. The F2 progeny plants of the cross GY-4 × PI12411 IF (gynoecious × monoecious) segregated 12 monoecious: 3 gynomonoecious or trimonoecious: 1 gynoecious, indicating a two recessive gene difference between gynoecy and monoecy. The backcross to the monoecious parent gave rise to monoecious plants, whereas the backcross to the gynoecious parent segregated 2 monoecious: 1 gynomonoecious: 1 gynoecious. The F2 progeny plants of the cross GY-4 × '36' (gynoecious × andromonoecious) segregated 36 monoecious: 12 andromonoecious: 9 gynomonoecious or trimonoecious: 4 hermaphrodite: 3 gynoecious, indicating a three recessive gene difference between the parents. The backcross to the andromonoecious parent segregated 1 monoecious: 1 andromonoecious, whereas that to the gynoecious parent segregated 2 monoecious: 1 gynomonoecious or trimonoecious: 1 gynoecious. The F2 gynoecious plants from the cross GY-4 × '36' segregated in F3 into 4 all progeny gynoecious: 10 mixed progeny of gynoecious (¾) and hermaphrodite (¼) plants. The results suggest that the monoecious, andromonoecious, and gynoecious parents carried the genes AAGGMM, aaGGMM, and AAggmm, respectively, for sex expression. The following phenotype–genotype relationships are proposed for sex expression in muskmelon: monoecious, A-G---; andromonoecious, aaG---; trimonoecious or gynomonoecious, AA-ggM-; hemaphrodite, aagg--; and gynoecious, A-ggmm.Key words: Cucumis melo, femaleness, germ plasm, F1 hybrids, cantaloupe, Cucurbitaceae, sex expression.