Metabolic modification to enhance resistance to Phytophtora infestans

LLORENTE BRIARDO; BRAVO ALMONACID, FERNANDO; TORRES, HÉCTOR N; FLAWIÁ, MIRTHA M; ALONSO, GUILLERMO

Mar del Plata - Argentina

Congreso; XLIII reunión Anual de SAIB; 2007

SAIB

It is well known that pathogen infection triggers the induction of defense-related reactions such as the natural accumulation of phenolic compounds like chlorogenic acid, lignins, flavonoids with phytoalexin activity and salicylic acid (responsible of the “systemic acquired resistance” or SAR). These metabolites are products of the phenylpropanoid pathway and are accumulated in infected tissues as a defense response to pathogen attack. There is a good correlation in plants between higher levels of phenolic compounds and enhanced resistance to pathogenic fungy. The intermediates and products of the phenylpropanoid pathway are excelent substrates for the polyphenol oxidase (PPO). This enzyme modifies these phenol containing molecules by hydroxylation and oxidation affecting their chemical properties. In order to enhance resistance to pathogenic fungy infection via indirect modifications of the phenylpropanoid metabolic pathway, PPO gene family was downregulated applying RNAi gene silencing. The transgenic potato plants with reduced PPO activity show a remarkable enhanced tolerance against P. Infestans when compared to WT potato plants and increased phenolic compounds accumulation colocalizing with the pathogen growth. As far as we know, this is the first report of a second generation transgenic functional food which also presents an enhanced resistance to plant pathogens.