Increased Postharvest Life of TomLox B Silenced Mutants of Tomato (Solanum lycopersicum) Var. TA234

Abstract

A healthy lifestyle includes fruits and vegetables consumption. Tomato is one of the most consumed vegetables, although it is susceptible to physical damage through postharvest handling, thus leading to important losses. Softening is an important variable during tomato ripening; excessive softening is undesirable and leads to postharvest losses. TomloxB plays an important role in ripening, mainly in the loss of cellular integrity caused by fatty acids released from the lipid matrix of membranes that initiate oxidative deterioration, which is in turn carried into senescence. In order to increase postharvest life, we produced transgenic tomato plants via Rhizobium radiobacter with tomato lipoxygenase B (TomloxB) antisense constructs under control of the cauliflower mosaic virus (CaMV) 35S promoter. Lipoxygenase activity and firmness were measured in tomato fruit and the fatty acids profile was determined. Transgenic fruits were maintained for 40 days at room temperature in optimal conditions, whereas wild type fruits remained in similar conditions for only six days. Firmness in pink and red stages was significantly lower in wild type fruits than in two transgenic lines. Linolenic acid was the most important fatty acid consumed by lipoxygenase in both turning and pink stages of ripening. Lipoxygenase activity was smaller in transformed fruits in comparison with the wild type. These results suggest that silencing the TomloxB gene promoted significant changes in the physiology of transformed tomatoes, being the increase in postharvest life the most important.

Lipoxygenase and Its Relationship with Ethylene During Ripening of Genetically Modified Tomato (Solanum lycopersicum)

“…1 ). In general, the highest activity was found in the pink stage, as reported by several authors ( 17 , 18 ). However, other authors found the highest activity at the red stage ( 1 , 8 ).…”

“…The decreased LOX activity in the transgenic lines is very likely a direct consequence of the TomloxB gene silencing, as León-García et al . ( 17 ) proved.…”

“…We used previously genetically transformed plant material prepared by León-García et al ( 17 ). These tomato plants ( Solanum lycopersicum var.…”

“…These tomato plants ( Solanum lycopersicum var. TA234) contain tomato lipoxygenase ( TomloxB ) gene in anti-sense constructs ( 17 ). In this study three transgenic lines: A-TR, B-TR and C-TR were used; each transgenic line was evaluated with 20 fruits.…”

“…Furthermore, ethylene is a gaseous plant hormone that triggers the maturation process in climacteric fruits and influences the senescence and abscission of the plant organs ( 14 ). It has also been implicated in developmental processes such as seed germination, cell elongation, root formation, sex determination, pollination and flowering, and it regulates plant responses to biotic and abiotic stress ( 14 , 15 ), and is related to ripening ( 16 , 17 ), as well as the production of fruit metabolites that act as part of defense mechanisms. Griffiths et al ( 1 ) determined that ethylene caused up-regulation of TomloxB expression in fruit but they did not study the effect of LOX on ethylene.…”