Cellulase involvement in the abscission of peach and pepper leaves is affected by salicylic acid.

Phenolic compounds appear to be involved in a number of regulatory activities in plants. During the last decade an increasing amount of evidence has brought to light the role played by salicylic acid in a number of physiological processes, Particularly interesting is the inhibitory effect of salicylic biosynthesis, which might make compound a useful tool for controlling some of the responses usually promoted by ethylene, Our data show that salicylic acid is actually able to reduce leaf abscission in both peach and pepper plants. Biochemical analyses have revealed that the enzyme usually involved in this phenomenon (cellulase, EC 3.2.1.4.) does not increase following activation oi leaf abscission in plants treated with salicylic acid, In contrast, control plants show a marked increase in the levels of both enzyme activity and cellulase protein, Flushing plants with exogenous ethylene in the presence of salicylic acid induces an increase in cellulase expression which, however, does not equal the level induced in plants without salicylic acid.