PO activity was inhibited in the susceptible varieties and enhanced in the resistant ones, and isoperoxidases reduced in the former and increased in the latter, after the treatment of etiolated 5 day-old seedlings, flag leaf discs and mitochondria with the toxin helminthosporal of different concentrations.On the other hand, the inhibition to PO varied with the degree of resistance in 3 varieties after the addition of the toxin into the extracts of flag leaves, ie. the more resistant the variety is, the less inhibited the PO activity is. It comes into the conclution that PO might be one of the ...
