Phenotypic characterization of pheophytinase-silenced tomato plants

• Grant number: 14/10185-0
• Support Opportunities: Scholarships in Brazil - Scientific Initiation
• Start date: July 01, 2014
• End date: January 27, 2015
• Field of knowledge: Biological Sciences - Biochemistry - Molecular Biology
• Principal Investigator: Maria Magdalena Rossi
• Grantee: Daniele Silva Pereira Rosado
• Host Institution: Instituto de Biociências (IB). Universidade de São Paulo (USP). São Paulo , SP, Brazil

Abstract

Chlorophyll (Chl) degradation is a constant catabolic process involved in pigment recycling in photosynthetically active cells and nutrient relocation in senescent leaves and ripening fruits. One product of Chl dephytylation is a lipophilic molecule named phytol, this molecule is part of the tocopherols, which are antioxidant compounds with Vitamin E (VTE) activity. It is proposed that the phytol molecule product of Chl breakdown could be incorporated during VTE synthesis, as a cross-link between these two metabolic pathways. Supporting this hypothesis, our research team identified genes enconding dephytylating enzymes, chlorophyllases, and proteins involved in phytol recycling, phytol kinases, associated to QTL (Quantitativa Trait Loci) for VTE content in Solanum lycopersicum fruits. In 2009, a new Chl dephytylating enzyme called pheophytinase was characterized in Arabdopsis thaliana. Up to date, no studies addressing this enzyme in tomato plants have been published. To better understand the relationship between Chl degradation during fruit ripening and VTE content, we intend to evaluate the phenotypic impact of pheophytinase deficiency in Solanum lycopersicum. In order to achieve this goal, this project proposes to perform a physiological and biochemical chacterization of pheophytinase-silenced transgenic plants.