Manipulation of leaf senescence and chlorophyll degradation aiming the fruit improvment

• Grant number: 12/04283-4
• Support type: Scholarships in Brazil - Doctorate (Direct)
• Effective date (Start): July 01, 2012
• Effective date (End): June 30, 2017
• Field of knowledge: Biological Sciences - Botany - Pant Physiology
• Principal researcher: Maria Magdalena Rossi
• Grantee: Bruno Silvestre Lira
• Home Institution: Instituto de Biociências (IB). Universidade de São Paulo (USP). São Paulo , SP, Brazil

Abstract

Recent studies are backing up the hypothesis of the vitamin E (VTE) benefits for human health, with great emphasis on the heart diseases prevention, breast cancer and protection against nicotine-induced oxidative stress. In plants, its function is not fully known, although many studies associate the VTE with the protection of pigments, proteins and polyunsaturated fatty acids of the photosynthetic apparatus against Reactive Oxygen Species (ROS) resultant of the photosynthesis. Besides that, it's proposed that VTE interacts with others antioxidant systems in order to maintain the intracellular redox homeostasis. The tomato fruit, as fresh or processed product, has a high nutritional value due to the diverse nutrient content, including VTE. The synthesis of VTE activity compounds, tocopherol and tocotrienol, occurs exclusively in photosynthetic organisms using precursors resultant of the shikimate and Methyl-Erythritol Phosphate (MEP) pathways. As an alternative to the MEP, it has been proposed that the lipophilic side chain can be suppressed by the chlorophyll degradation. This process, associated with the senescence and fruit ripening, is related with the chlorophyllase activity and, more recently, with the pheophytinase activity, since one of the catalyzed reaction products is the phytol. Thus, this project aims to investigate the inter-relationship between the VTE biosynthesis pathway and the chlorophyll degradation by a functional study of two chlorophyllase (Slchl3 e Slchl4) and one pheophytinase (Slpph), recently indentified in S. lycopersicum. Finally, it will be verified the impact in the VTE content due to the manipulation of these genes by phenotypic characterization of silenced plants for these three genes of interest. (AU)