Modification and Dominance of the Gene Governing Formation of High Concentrations of BETA-Carotene in the Tomato.

ROM the progeny of crosses between normal canning tomatoes, LycoperF sicon esculentum Mill., and the wild species L. hirsutum Humb. and Bonpl., LINCOLN et al. (1943) and KOHLER et al. (1947) isolated a new tomato type which was distinguished from normal tomatoes by producing orange fruits in which most of the carotene produced was beta-carotene. From the study of a cross between the red canning variety Indiana Baltimore and a true breeding, high beta-carotene orange strain, LINCOLN and PORTER (1950) postulated that in high beta-carotene orange tomatoes the shift from red (lycopene) to orange (beta-carotene) depended upon a single gene B which lacked dominance. TOMES et al. (1953) demonstrated t h t the gene B was not an allele of either R / r (red/yellow flesh, high/low total carotene) or T/t (red/tangerine flesh, lycopene/prolycopene, zeta-carotene type) and that in the F1 and F Z generations of crosses involving the beta orange type with yellow-fleshed or tangerine-fleshed types the gene B appeared to behave as originally postulated. These authors noted, however, that considerable evidence was available which inferred that B might actually be a dominant gene and that the F1 and Fz values reported might be accounted for by modification. The purpose of the present paper is to clarify the dominance of the alleles B/b and the mode of inheritance of high concentrations of beta-carotene in the tomato.