Genetic analysis of tomato [Lycopersicon esculentum Mill.] twin forms

The aim of the study was to determine the origin of additional embryos on the basis of marker characters observed in the phenotype of twin pairs of F2 and F3 generations of two hybrid cultivars of tomato (Alonso and Carmello). The marker characters were the presence/absence of the so-called green back, and the type of growth, which can be indeterminate or determinate. Among 112 F2 twins, differences in marker characters were observed in 24 pairs. In the material derived from Alonso, 9 of 18 observed F3 progenies did not show segregation in marker characters. Progenies of Carmello had higher variability; only 12 of 28 progeny groups showed no recombinants. Analysis of the F3 generation enabled further limitation of the sources of additional embryos. Segregation of any marker character excluded the possibility that a particular F2 twin was formed from a haploid cell of the embryo sac after spontaneous doubling of chromosome number.