CONICET | Buscador de Institutos y Recursos Humanos

The main goal of this study was to generate potato plants with modified antioxidant capabilities by decreasing polyphenol oxidase (ppo) levels. To accomplish this, a vector carrying a hairpin construct designed to silence ppo gene family was introduced into the Spunta variety of potato by Agrobacterium transformation and several transgenic plants were generated, most of them with reduced ppo activity. The ppo gene silencing resulted in an inhibition of the enzymatic browning, thus transgenic potato tubers dont turn black once cut or peeled. Unexpectedly, modified tubers also present improved aroma and were consumed significantly more often than wild type (wt) tubers in mouse feeding experiments. Modified potato plants show no growth or tuber yield differences compared to wt in green house experiments. Interestingly, transgenic potato plants possess an enhanced resistance to Pytophthora infestans, the causal agent of potato and tomato late blight, when compared to wt plants. Furthermore, transgenic plants accumulate higher amounts of defensive phenolic compounds during pathogen infection. A possible mechanism for the observed resistance could be that ppo silenced plants possess an elevated metabolic flux of non-oxidized antimicrobial phenolics. This higher availability of free phenolics could also operate in advanced steps of the infection by cross-linking cell wall components.