Regulatory change in cell division activity and genetic mapping of a tomato (Solanum lycopersicum L.) elongated-fruit mutant

抄録

Tomato elongated-fruit mutants have proven useful for elucidation and mapping of genes that regulate fruit elongation. We previously identified a novel tomato mutant, Solanum lycopersicum elongated fruit1 (Slelf1), which exhibits an elongated fruit shape caused by increased cell layers in the ovary proximal region, and located the causal genes on the long arm of chromosome 8. In this study, we isolated and characterized two independent tomato mutants, Solanum lycopersicum elongated fruit2 and 3 (Slelf2 and Slelf3). Histological analysis revealed that the Slelf2 mutant ovary displayed an overall elongated shape, whereas the developing ovary of the Slelf3 mutant was primarily expanded in the proximal region. We developed an intra-specific F₂ population by crossing Slelf3 with Ailsa Craig, a related cultivar. Mapping of this population confirmed that the candidate gene of the Slelf3 mutation was positioned on the short arm of chromosome 7, in a region of approximately 0.4 Mb. These results indicate that the causal gene is a novel locus differing from previous genes known to affect fruit shape elongation in tomatoes. In addition, analysis of transcript levels of genes related to cell division and expansion in the Slelf3 mutant suggested that the mutated gene most likely regulates cell division activity, predominantly in the proximal region.