Detection of 3-hydroxy-3-methylglutaryl-coenzyme A reductase protein Cm-HMGR during fruit development in melon ( Cucumis melo L.)

The fruit size of melon (Cucumis melo L. reticulatus) is determined by the amount of cell proliferation in the pericarp during early fruit development. During this stage, expression and activity of the 3-hydroxy-3-methylglutaryl coenzyme A reductase (HMGR) gene is required for fruit growth. In this study, we performed a detailed analysis of the correlation between the expression of melon HMGR (Cm-HMGR) protein and cell division in the pericarp. Flow cytometric analysis revealed that the length of the cell division stage was correlated with the fruit size. Western gel blotting and tissue printing illustrated the temporal and spatial accumulation pattern of Cm-HMGR protein during fruit development. The accumulation of Cm-HMGR transiently increased at the beginning of the cell division stage in the pericarp, where active cell division occurred. The amount of Cm-HMGR was correlated with the length of the cell division period. These results strongly suggest that the expression of Cm-HMGR is involved in the determination of melon fruit size by regulating cell division during early fruit development.