Influence of ripening modulation compounds on ascorbic acid metabolism in fruits: the 1-methycyclopropene and ethylene treatment effects

• Grant number: 05/01959-3
• Support Opportunities: Regular Research Grants
• Start date: November 01, 2005
• End date: October 31, 2007
• Field of knowledge: Agronomical Sciences - Food Science and Technology - Food Science
• Principal Investigator: Franco Maria Lajolo
• Grantee: Franco Maria Lajolo
• Host Institution: Faculdade de Ciências Farmacêuticas (FCF). Universidade de São Paulo (USP). São Paulo , SP, Brazil

Abstract

The ascorbic acid (AA) content may vary significantly during fruit ripening, depending on several factors such as specie and cultivar. The mechanisms which control these changes are still unknown, but it was verified that enzymatic activities of ascorbate synthesis, degradation and regeneration show great influence on it. Beside this, the superexpression of an isolated enzyme is not capable of increasing significantly the AA content in plants. This work will study the influence of two ripening modulation compounds (ethylene and 1-methylcyclopropene, 1-MCP) in guavas, in order to comprehend the mechanism used for the regulation of AA. The enzymatic activities of ascorbate synthesis (GDP-D-mannose-3,5-epimerase, L-galactose dehydrogenase and L-galactono-1,4-lactone dehydrogenase), degradation (ascorbate oxidase and ascorbate peroxidase) and regeneration (monodehydroascorbate reductase and dehydroascorbate reductase), the content of AA precursors, and the ethylene and 1-MCP influence on these parameters will be monitored during fruit ripening. The protein expression of GDP-D-mannose-3,5-epimerase and L-galactose dehydrogenase will be analyzed in different ripening stages for treated and non treated samples, in order to correlate it with the detected activities. (AU)