RIPENING AND CELL-WALL SYNTHESIS IN NORMAL AND MUTANT TOMATO FRUIT

Cell wall synthesis during development of 'Rutgers', rin and nor tomatoes was quantified at different 'ripening' stages by measuring incorporation of C-14 into pericarp cell walls 18 hr after pedicel injection of [U-C-14]sucrose. Colour (Hunter 'a' and 'b' values) and pericarp firmness were also monitored. Incorporation of C-14 into walls continued throughout ontogeny in 'Rutgers' fruit and exhibited a transient increase from late mature-green (36 days post-anthesis; DPA) to the turning stage (41 DPA). Incorporation of C-14 into walls of rin pericarp was similar to immature green 'Rutgers' (20 DPA) but decreased to a level similar to red (46 DPA) 'Rutgers' fruit by 35 DPA. Incorporation of C-14 into nor cell walls was low throughout the experimental period (20 to 75 DPA). In contrast to previous reports, rin and nor pericarp exhibited a decrease in firmness. However, softening was slower than in 'Rutgers'. Pericarp from rin and nor at 70 and 75 DPA, respectively, resisted compression as much as pink (43 DPA) 'Rutgers' pericarp.