Postharvest Analysis of Lowland Transgenic Tomato Fruits Harboring hpRNAi-ACO1Construct
The plant hormone, ethylene, is an important regulator which involved in regulating fruit ripening and flower senescence. In this study, RNA interference (RNAi) technology was employed to silence the genes involved in ethylene biosynthetic pathway. This was achieved by blocking the expression of specific gene encoding the ACC oxidase. Initially, cDNA corresponding toACO1of lowland tomato cultivar (MT1), which has high identity withACO1ofSolanum lycopersicumin GenBank, was cloned through RT-PCR. Using a partial coding region ofACO1, one hpRNAi transformation vector was constructed and expressed ectopically under the 35S promoter. Results showed that transgenic lines harboring the hpRNA-ACO1construct had lower ethylene production and a longer shelf life of 32 days as compared to 10 days for wild-type fruits. Changes in cell wall degrading enzyme activities were also investigated in cases where the transgenic fruits exhibited reduced rates of firmness loss, which can be associated with a decrease in pectin methylesterase (PME) and polygalacturonase (PG) activities. However, no significant change was detected in both transgenic and wild-type fruits in terms ofβ-galactosidase (β-Gal) activity and levels of total soluble solid, titratable acid and ascorbic acid.