Expression of the tobacco gene CBP20 in response to developmental stage, wounding, salicylic acid and heavy metals

The pathogenesis-related (PR)-protein CBP20 which is a basic representative of the, group PR-4 is similarly regulated as the basic protein class-I beta-1,3-glucanase and class I chitinase of PR-2 and PR-3, respectively. It shows complex hormonal, developmental and pathogenesis-related regulation. The protein is constitutively accumulated in suspension-cultured cells, in roots and in lower source leaves of healthy tobacco plants, but not in upper, sink leaves near the top of the plant. After spraying the plants with salicylic acid, the protein CBP20 was also detected in sink leaves, indicating a potential function of salicylic acid in the signal transduction pathway. Synthesis of CBP20 is inducible by heavy metals, especially zinc chloride, which was shown by Northern and Western blotting. We have demonstrated that the accumulation of mRNA not always resulted in accumulation of the appropriate protein leading to the suggestion that expression of CBP20 is transcriptionally as well as post-transcriptionally regulated by more than one response pathway. (C) 1999 Published by Elsevier Science Ireland Ltd. All rights reserved.