Peroxidase isozymes in healthy potato leaves of Solanum thberosum(Norin No. 1. Irish Cobbler and Benimaru) and interspecific hybrids between S. demissum and S. tuberosum(SH-469, 96-56 and 1506-(b)9, and those infected with Phytophthora infestans, were seperated with acrylamide-gel electrophoresis and stained with benzidin acetate and hydrogen-peroxide.
Nine bands of peroxidase isozymes were recoginzed from Solanum thberosum(Norin No. 1) and interspecific hybrids between S. demissum and S. tuberosum(96-56 and SH-469) and ten bands were found on interspecific hybrid 1506-(b)9.
Peroxidase activity was higher on lower leaves than on upper ones. The increase of peroxidase activity was recognized on potato hybrid leaves infected with Phytophthora infestans (Rase 0). The increase of the activity was also recognized on the interspecific hybrid 1506- (b)9(incompatible to Race 1) infected with Race 1 of Phytophthora infestans, but the increase was not found on susceptible Norin No. 1 and interspecific hybrid 96-156 (compatible to Race 1).
Leaves of grafted potatoes (common varieties and hybrids) showed higher activity of peroxidase than the control. Peroxidase activity on the grafted plants was higher in stocks than in scions.
Higher activity was found on potato leaves placed the DNA-containing fraction of different varieties.