DIVERSITY IN OCTADECANOID-INDUCED GENE-EXPRESSION OF TOMATO

In tomato plants wounding leads to up-regulation of various plant defe nse genes via jasmonates (Ryan, 1992; Bergey et al., 1996). Using this model system of jasmonic acid (JA) signalling, we analyzed activity o f octadecanoids to express JA-responsive genes. Leaf treatments were p erformed with naturally occurring octadecanoids and their molecular mi mics such as coronatine or indanone conjugates. JA responses were reco rded in terms of up- or down-regulation of various genes by analyzing transcript accumulation, and at least partially in vitro translation p roducts and polypeptide pattern of leaf extracts. The data suggest: (i ) 12-Oxo-phyrodienoic acid and other intermediates of the octadecanoid pathway has to be beta-oxidized to give a JA response. (ii) Octadecan oids which can nor be beta-oxidized are inactive. (iii) JA, its methyl ester (JM), and its amino acid conjugates are most active signals in tomato leaves leading to up regulation of mainly wound-inducible genes and down-regulation of mainly <house-keeping> genes. (iv) Some compou nds carrying a JA/JM- or JA amino acid conjugate-like structure induce /repress only a subset of genes suggesting diversity of JA signalling.