Leaf Proteome Profiling and Their Interactions To Determine Disease Resistance in Grape

The mechanism of solar radiation transformed in the grape berry as a sink through grape leaves is the most important factor affecting the quantity and quality of the fruit yield. Florida Hybrid bunch (FH) grape is widely cultivated in US southeast region and is popularly known for wine and table grape. However, most commercial cultivars are highly susceptible to anthracnose and to various foliar diseases. Our goal was to determine molecular mechanisms involved in the grape leaf during the berry development and anthracnose disease tolerance. The specific objective of this study was to determine genetic diversity of leaf protein composition among different cultivars of Florida hybrid bunch grape during their berry development and better understand their role in disease tolerance characteristics. Leaf proteins from various FH cultivars were resolved on 2DE and characterized using Mass Spectrometry and the Vitis database. Comparative analysis of eight FH cultivars revealed 56 differentially expressed proteins mainly belonging to pathogen response, photosynthesis, and metabolism. Tolerant cultivars showed a greater overall abundance of proteins compared to susceptible cultivars.  Interaction studies between photosynthetic related proteins suggest chlorophyll a/b binding proteins and photosystem 1 light harvesting proteins are more dominant in tolerant cultivars.  Enzyme activity assay and real time PCR studies of selected genes and enzymes suggest a positive correlation with protein expression among cultivars. Protein expression, in particular photosynthesis related, in grape leaves is attenuated during berry development and ripening. Expression of antioxidant proteins such as superoxide dismutase and peroxidase declined in leaf at the early ripening stage suggesting a positive relationship connecting the source and sink organs of the FH bunch grapes.