Published 2009-12-01
Abstract
Grape berries rely on the use of available carbohydrates produced by photosynthesis to support their growth and development. In view of the unique physiology and genetic make-up of muscadine, bunch, and Florida hybrid bunch grapes, this study was focused on proteomics of leaves to increase our knowledge of Vitis leaf proteome. A high throughput two-dimensional gel electrophoresis (2-DE) was conducted on muscadine (Vitis rotundifolia), bunch (Vitis vinifera), and hybrid bunch (Vitis spp.) leaf proteins to document complexity in their composition. Grape leaf proteins resolved into >260 polypeptides with pIs between 3.5 and 8.0 and molecular weight between 12,000 to 100,000 daltons. Most of the leaf proteins were found to be in the 80, 60, 40, and 20 kDa range with pI between 4.5 and 8.0. Comparative analysis of gels showed that 52 polypeptides varied among the Vitis species. These polypeptides ranged in Mr between 14,420 and 88,600 daltons, and pI between 4.93 and 9.32. Muscadine leaves contained signifi cantly higher amount of polypeptides with molecular weight around 65 kDa and pI between 6.0 and 7.5. These data clearly demonstrate that leaf polypeptide content and composition of Vitis species signifi cantly differ and that these variations may contribute to their unique characteristics.