INDUCTION OF TOMATO STRESS PROTEIN MESSENGER-RNAS BY ETHEPHON, 2,6-DICHLOROISONICOTINIC ACID AND SALICYLATE

To study the possible involvement of plant hormones in the synthesis o f stress proteins in tomato upon inoculation with Cladosporium fulvum, we investigated the induction of mRNAs encoding PR proteins and ethyl ene biosynthesis enzymes by ethephon, 2,6-dichloroisonicotinic acid (I NA) and salicylic acid (SA) by northern blot analysis. Ethephon slight ly induced some but not all mRNAs encoding intra- and extracellular PR proteins. INA induced all PR protein mRNAs analysed, except for intra cellular chitinase and extracellular PR-4. SA induced all PR protein m RNAs analyzed, except for intracellular chitinase and osmotin. None of the inducers affected the expression of ACC synthase mRNA, whereas al l three induced ethylene-forming enzyme (EFE) mRNA.