IDENTIFICATION OF METHYL JASMONATE AND SALICYLIC-ACID RESPONSE ELEMENTS FROM THE NOPALINE SYNTHASE (NOS) PROMOTER

Transgenic tobacco plants carrying a fusion between the nopaline synth ase (nos) promoter and chloramphenicol acetyltransferase (CAT) reporte r gene (cat) were studied for their inducibility by salicylic acid (SA ) or methyl jasmonate (MJ) treatments. Either chemical significantly i ncreased CAT activity to a level much higher than that achieved by wou nding. Northern blot analysis showed a corresponding increase in mRNA levels. After 20 h of induction of flowering plants, the response to M J treatment was weaker in old leaves compared with young leaves, where as the SA response was stronger in old leaves. Kinetic experiments sho wed that the SA response was much faster than the MJ response, suggest ing that the induction mechanism of the nos promoter by these chemical s may differ. Deletion analysis showed that both SA and MJ responses r equire the DNA sequence between -119 and -112 from the transcription i nitiation site. This region contains the hexamer sequence (TGACGT) tha t has been found to be an important regulatory element for several pro moters. The MJ response was also reduced by deletions of the CAAT box region or the sequence between -112 and -101, whereas the SA response was not significantly affected by these deletions. This suggests that the nos upstream region containing the hexamer motif is essential for the SA or MJ response and that the CAAT box region and the sequence im mediately downstream from the hexamer motif are required for maximum i nduction by MJ.