Abstract:

Two poplar species with different resistance (Populus tomentosa, a resistant one; P. beijingensis, a susceptible one) to a canker disease were used to study the dynamic changes of cell membrane permeability, soluble sugar and MDA content in the callus inoculated with the pathogen of Botryosphaeria dothidea. After inoculation, cell membrane permeability of two species increased with a significant raise of relative electrical conductivity, and the increment in the susceptible species was higher than that in the resistant one. The pattern of changes in soluble sugar with time varied in the two species. Soluble sugar content in susceptible species occurred two peaks, respectively at 24 h and 120 h. The resistant species had higher soluble sugar content than that of the uninfected control at 48 h, however its increment was smaller than the latter. There was no significant difference in the soluble sugar content between the inoculated and its control of the resistant species. MDA content increased in the susceptible species, while no significant change was observed in the resistant one. The result showed that serious lipid peroxidation occurred in the susceptible species.

Key words: Populus tomentosa, Populus beijingensis, Botryosphaeria dothidea, poplar callus, cell membrane permeability, relative electrical conductivity, malonyldialdehyde (MDA), soluble sugar