Isolation of New Parthenocarpic Mutants and Pistil-Specific Promoter for Production of Parthenocarpic Cultivars in Tomato (Solanum lycopersicum)

Parthenocarpy is a valuable trait for farmers and consumers in fruit production. Mutations in genes associated with induction of pathenocarpic fruit formation often has pleiotropic effects and are associated with unfavorable characteristics, such as male or female sterility. Therefore, isolation of new parthenocapic mutants without them and pistil-specific promoters for genetic engineering would be useful in production of parthenocarpic cultivars. However, little is known about the mechanism by which parthenocarpy is induced in fruit bearing crops.

 In order to get insight into the mechanism, a comprehensive mutant population was generated in the background of ‘Micro-Tom’, small size, short life cycle and easy transformability variety. For six years effort, a family including 16,000 M2 mutagenized lines has been produced by ethylmethan sulfonate treatment and gamma-ray irradiation, and six mutants with parthenocarpic fruit development were isolated.

 With the aim to identify pistil-specific genes, RNA-Seq was carried out. Of 1,714 genes expressing in pistil, 79 highly expressed were selected in comparison of genes expressing in pistil with those in other tissues. It also proved in RT-PCR analysis that seven of the 79 genes were specifically expressed in pistil.  In the future, we are planning to use promoters of these pistil-specific genes as possible genetic tools to produce parthenocarpic cultivars without undesirable characteristics.

 This project is supported by the Programme for Promotion of Basic and Applied Researches for Innovations in Bio-oriented Industry and Grant-in-Aid for Scientific Research on Innovative Areas “Genome Science from Ministry of Education, Culture, Sports, Science and Technology of Japan (No.221S0002).