Transformation of Tomato with the Melon 3-Hydroxy-3-Methylglutaryl Coenzyme A Reductase Leads to Increase of Fruit Size

The expression of 3-hydroxy-3-methylglutaryl coenzyme A reductase (HMGR) is involved in the determination of final fruit size of tomato (Lycopersicon esculentum Mill.). We developed transgenic tomatoes that over-expressed the melon (Cucumis melo L. reticulatus) Cm-HMGR-CD gene, which encodes the catalytic domain of HMGR. The derived transgenic plants expressed Cm-HMGR-CD. Flow cytometric analysis revealed that cell division and/or elongation in the fruit pericarp during early fruit development was induced more rapidly in the transgenic plant than in the wild-type control. The fruit size in transgenic plants was larger than that in controls. The growth of fruit pericarp also enhanced in transgenic plants. These results suggest that HMGR might stimulate pericarp development by activation of cell division and/or elongation (differentiation), and thereby affects fruit size. In addition, the constitutive expression of Cm-HMGR-CD affected plant morphology. Thus, transgenic plant growth was suppressed and the leaves accumulated higher levels of chlorophyll, as compared to wild-type control plants.