A Novel Ditertiary Tetrasomic in Tomato

Cytogenetic studies were carried out on a ditertiary tetrasomic, 2n + 2 (5L.7S), of tomato (Lycopersicon esculentum Mill.). In studies of transmission of the 5L.7S chromosome, male and female rates of 57.1% and 74.5%, respectively, were found-the highest yet reported for any tomato aneuploid. Additionally, two 5L.7S tertiary chromosomes were transmitted through the female gametophyte, the maximum duplication known to be tolerated by this developmental stage. Monotertiary tetrasomics of a novel type, 2n + 5L.5S + 5L.7S, were recovered in the selfed progeny of 2n + 2(5L.7S). The usefulness of the ditertiary tetrasomic for the production of double trisomics and for dosage and experimental evolutionary studies is elaborated.