During growth and maturation, grape berries switch from a status where they are small, hard and acidic, with little sugar, to a status where they are larger, softer, sweeter, less acidic and strongly flavoured and coloured. Photoassimilate and ion transport and compartmentation into the vacuole are important steps in grape berry development. Many research groups, including our own, have provided significant progresses in this research area; however the unlocking of the secrets behind grape berry ripening is still a major scientific challenge. Since the late 1800’s when the Bordeaux mixture was developed, copper has been widely used, in particular in the organic farming, as the active principle of several fungicides used to prevent the attack of pathogens such as downy mildew. Despite its essential role in several metabolic processes such as photosynthesis, respiration, antioxidant activity, cell metabolism and hormone perception, excessive copper may induce alterations in the cell metabolism and in the total content of several important compounds in grape, including total nitrogen and soluble sugars, and be a cause of phytotoxicity. In the present project, molecular and biochemical approaches will be combined to investigate the uptake mechanisms and detoxification steps of copper in grape cells. Special emphasis will be given to the cloning of copper transporters and subsequent gene description. Heterologous expression will be performed in model systems such asArabidopsisandSaccharomyces cerevisiae, allowing subcelullar localization and biochemical studies. Further characterization of the transporters will be achieved by homologous expression in grape berry protoplasts. Gene expression will be analyzed in different grapevine organs and in grape berry tissues during different stages of development.In silicostudies will allow prediction of the structure of the transporters, as well as of post-translational modifications.
Hernâni Varanda Gerós