A new diploid chromosome number for tomato (Lycopersicon esculentum)?

Abstract

The recognized chromosome number of tomato has been 2n = 24. In this paper the chromosome number 2n = 26 is reported in 18 varieties of tomato. One commercial hybrid variety, revealed 25 mitotic chromosomes. This variety, as well as the varieties with 26 chromosomes, appeared to be fully fertile. Different chromosome numbers did not appear to be associated with any morphological differences between the varieties examined. Preliminary meiotic examination of the variety 'Flora-Dade' (2n = 26 mitotic chromosomes) sometimes revealed 12 associations of chromosomes and sometimes 13 associations. Meiotic examination of the variety 'Sunny' (2n = 25 mitotic chromosomes) revealed what appeared to be 12 bivalents. Centric fission may account for the numerical variation of the diploid chromosome number of tomatoes.Key words: Lycopersicon, tomato, chromosome number, centric fusion.