The relationship between hypersensitive tissue and resistance in wheat seedlings infected with Puccinia graminis tritici

SUMMARY Data obtained during the first 120 hr. of the infection process in several resistant and susceptible varieties of wheat infected with Puccinia graminis tritici did not show any consistent relationship between the growth of the rust colony and the rate of increase of host tissue showing hypersensitive necrosis. Furthermore, no apparent relationship existed between the area of the rust colony at any given time after inoculation, and the amount of hypersensitive necrotic tissue per unit area of the leaf colonized. Thus, it is suggested that hypersensitive necrosis of the host tissue is a consequence and not the cause of resistance of wheat to infection by P. graminis tritici.