Electrolyte leakage from necrotizing tissues of Japanese black pine (Pinus thunbergii) inoculated with pine wood nematodes

Abstract

Plants change their cell permeability in response to stresses. Relations between electrolyte leakage and cell death of pine tissues inoculated with pine wood nematodes were examined in cuttings of current-year shoots and 3 year-old seedlings. Abnormal electrolyte leakage and cell death in inoculated cuttings were observed 6 days after inoculation and then, they progressed together with multiplication of nematodes. Remarkable leakage from xylem tissues preceded disappearance of cell nuclei dyed with DAPI. In 3 year-old seedlings, although nematodes in inoculated shoots multiplied 15 days after inoculation, abnormal leakage wasn't observed till 20 days. And the leakage suddenly occurred after 30 days in inoculated current-year shoots where cell nuclei dyed with DAPI almost disappeared. So, the pattern of electrolyte leakage from pine tissues inoculated with pine wood nematodes was different between two experiments. Only inoculated branches wilted in these seedlings, so that it was suggested that the pattern of the leakage was different because of delay of the disease development.