Abstract
The process of hypersensitive death of a potato cell infected by an incompatible race of Phytophthora infestans was observed by using a temperature controlled, inverted microscope. More precise observation than in previous experiments disclosed that the process of hypersensitive death of the cells consisted of at least two phases: cessation of protoplasmic streaming and then loss of stainability of vacuole with neutral red. The infected cell still maintained stainability with neutral red and could absorb it after the protoplasmic streaming stopped. After a while, the cell lost the stainability with neutral red. The effect of temperature on this process was investigated. The time elapsed from inoculation to the penetration was longer at 20C than at 25 and 30C.
By extraporating the growth curve of the intracellular hyphae to O, length of the penetration was judged to finish 10-15min before the hyphae become actually visible, so that the time required for hypersensitive cell death is longer than that estimated in prlor experiments.
In 10-20% of the cut surface cells inoculated 18hr after cutting, protoplasmic streaming stopped about 30min after penetration (at 20, 25 and 30C) and in 50% of the cells protoplasmic streaming stopped about 37min (20C) 40min (25C) and 45min (30C) after penetration. The cells seemed to lose their stainability with neutral red about 30min (20C), 10min (25C) and 10min (30C) after protoplasmic streaming stopped.
