VIEW ARTICLE

Physiology and Biochemistry

Superoxide Anion Generation: A Response of Potato Leaves to Infection with Phytophthora infestans. H. B. Chai, Plant Pathology Laboratory, Faculty of Agriculture, Nagoya University, Chikusa-Ku, Nagoya 464, Japan; N. Doke, Plant Pathology Laboratory, Faculty of Agriculture, Nagoya University, Chikusa-Ku, Nagoya 464, Japan. Phytopathology 77:645-649. Accepted for publication 22 July 1986. Copyright 1987 The American Phytopathological Society. DOI: 10.1094/Phyto-77-645.

In potato leaves inoculated by a zoospore suspension of Phytophthora infestans, O₂^– generation appeared at two stages, before and after fungus penetration. The former reaction was only temporal in leaves that were inoculated with either the compatible or incompatible races of P. infestans. This reaction was also activated by zoospore germination fluid. The latter reaction, however, was characteristic of the incompatible, but not the compatible interactions, with respect to the occurrence of a hypersensitive cell reaction following fungus penetration. An O₂^– generating reaction before fungus penetration was also found to be activated in some nonhost plant leaves that were either inoculated with the fungus or treated with the germination fluid. However, a few penetrating fungi in these nonhost plants resulted in no detection of enhanced O₂^– generation after fungus penetration. These results suggest that intact leaves may recognize some substance released from germinating spores that activates an O₂^– generating reaction, and that further activation of O₂^– generating reaction may occur in potato leaf tissues in close association with a hypersensitive reaction elicited by penetration by incompatible races of P. infestans.