Molecular Breeding of Tomato Lines for Mass Production of Miraculin in a Plant Factory

A transgenic tomato line (56B, Moneymaker) that expresses the miraculin gene driven by the CaMV 35S promoter was crossed with a dwarf tomato (Micro-Tom) for the molecular breeding of cultivars that are suitable for miraculin production in a closed cultivation system. Plant size, miraculin accumulation, and self-pruning growth were used as selection indicators for F-2 plants. Two lines were chosen for further analysis, bred to the F-6 or F-7 generation and cultivated in a closed cultivation system. In 56B and the two crossed lines, the concentrations of miraculin in the pericarp were 140, 367, and 343 mu g/g FW, respectively. We also estimated that 26.2, 73.6, and 45.9 kg FW/m(2) of tomatoes and 2.2, 16.6, and 9.8 mg/m(2) of miraculin in the pericarp, respectively, could be harvested per year. These two crossed lines will be useful for the mass production of miraculin, especially in a closed cultivation system.