DNA isolation, Southern blot and segregation analysis
Total plant DNA was isolated from young tomato leaf material following the method described by Dellaporta et al. (1983) . For Southern blot analysis, approximately 10 μg restricted DNA was subjected to electrophoresis through 0.8% agarose and blotted onto Hybond N+ membranes. Hybridization was performed at 65°C under standard conditions ( Sambrook et al. 1989 ). Segregation analysis between famutation and the deletion found in the TOFL gene of fa plants was performed with genomic DNA from 240 F2 plants segregating for the famutation. DNA of each individual plant was used in a PCR reaction with a set of 33P-labelled TOFL-specific primers (5′-CGC AGA TAT TTC GGT GG-G ACC-3′ and 5′-ATT CCT CCA CCT CCA CCT CCT TGG-3′). The PCR products were run in 5% polyacrylamide gels and exposed to X-ray films.