Cadmium transport and accumulation of different tomato genotypes: physiological, proteomic and molecular approaches.

Abstract

In the last decades, agriculture has been changed with arising of new scenarios of environmental problems, especially those involving the contamination of soil and water with heavy metals. These problems are more serious when we consider that metals such as cadmium (Cd) can easily enter in food chain by their absorption via the roots of the plant species used as foods. Although several studies have been conducted to understand the Cd impact on oxidative metabolism of crops, there are little information about the kinetics of uptake and accumulation of this metal in the tissues, as well as on dynamic of responses in biochemical and molecular levels throughout the process. This information is extremely important because they can ravel mechanisms response to Cd and mechanisms of tolerance in an integrated and complex system. Then, objective of this work is characterize the physiological, biochemical and molecular changes during the process of absorption and Cd accumulation, through the integrated analysis of all these processes using sensitive tomato genotypes to this metal. We hope to draw a map in which the processes of absorption and Cd accumulation in tomato plants are monitored from the first moment in which the plants come into contact with the metal until the time that they are under chronic stress. Associated with these kinetic studies of absorption and Cd accumulation, we intend to trace the cellular antioxidant system response profile, in addition to conducting the study on protein change, phytochelatin synthesis and molecular level of expression of genes related to the transport of ions on solution to the plant via root tissues. For that, we will apply methodology of analysis of Cd uptake kinetics and nutrients over time, conducting experiments with plants in hydroponics system, to identify the most important times of recognition and response to stress. In addition, we will use reciprocal grafting between tolerant and susceptible tomato genotypes, as tools to study the signaling between the root system and aerial parts of the plants during the process of absorption and metal accumulation in tissues. These results and the previous knowledge of other researches involving the response of crops to Cd exposure, aggregating the experience of our research group, certainly will generate relevant information, which will be published in good refereed international journals that are respected in the field. (AU)