BETA-1,3-GLUCANASE, CHITINASE, AND PEROXIDASE-ACTIVITIES IN TOBACCO TISSUES RESISTANT AND SUSCEPTIBLE TO BLUE MOLD AS RELATED TO FLOWERING, AGE AND SUCKER DEVELOPMENT

Tobacco becomes naturally resistant to blue mould caused by Peronospora tabacina as it ages. This age-related resistance is correlated to the time of normal floral development and the senescence of lower leaves: however, it is dependent on neither. β-1,3-Glucanase, chitinase and peroxidase activities increase in tobacco with age. These increases correlate with the development of age-related resistance to blue mould and were independent of floral development. Additionally. β-1,3-glucanase, chitinase, and peroxidase activities were higher in leaf tissue from the main stalk resistant to blue mould) as compared to leaf tissue from suckering stems (susceptible to blue mould) on the same plant. Isozyme patterns of β-1,3-glucanase and chitinase in all resistant tissues are typical of those of tissues systemically protected by either stem injection with Peronospora tabacina or foliar inoculation with TMV. © 1991.