Abstract
Peroxidase and phenol oxidase activity, O2-uptake, total phenols and o-diphenols content were determined for tubers of twenty two white potato varieties. The degree of resistance of the tuber tissues to Phytophthora infestans was evaluated for each variety by estimating spore production on the cut surface of tuber. In the case of resistance of tuber tissues to an incompatible race of P. infestans, the varieties exhibiting higher levels of peroxidase and phenol oxidase activity, and higher concentrations of o-diphenols were always highly resistant, but those having lower concentrations of o-diphenols were not necessarily susceptible. In the cases of tubers which were resistant to the compatible race (that is, field resistance of susceptible varieties), on the contrary, these correlations were not apparent.
Apparent correlations were found between phenol oxidase activity and peroxidase activity, phenol oxidase activity and oxygen uptake, peroxidase activity and o-diphenols content, oxygen uptake and total phenol content, total phenol content and increase in o-diphenols content, and o-diphenols content and increase in o-diphenols content.
