REGULATION OF THE WOUND-INDUCED MYROSINASE-ASSOCIATED PROTEIN TRANSCRIPT IN BRASSICA-NAPUS PLANTS

Two slightly differing cDNA clones corresponding to the wound-inducibl e form of a previously characterized seed myrosinase-associated protei n (MyAP) have been isolated from Brassica napus L. The transcripts cor responding to the induced MyAP (iMyAP) were found to be developmentall y regulated in various vegetative organs. Both young and old leaves ex hibited wound-inducible iMyAP expression. Furthermore, in the young pl ant, wounding resulted in a systemic increase in leaves located both a cropetally and basipetally to the wounded leaf. Also, the iMyAP transc ripts were induced by methyl jasmonate, jasmonic acid and abscisic aci d. The different inductions could be antagonized by salicylic acid. A general responsiveness in methyl-jasmonate-treated leaves was demonstr ated by in situ hybridization. No effect on the amount of iMyAP transc ript was detected after feeding the plants with the ethylene precursor 1-aminocyclopropane-1-carboxylic acid. The similarity between MyAP an d a lipase from Arabidopsis thaliana indicated a possible function in liberating acylated glucosinolates from their acyl group, thereby maki ng them available for hydrolysis by the myrosinase enzymes. We also re port on a reduction in the amount of myrosinase transcripts derived fr om the vegetatively expressed MB-gene family after treatment with exog enously applied salicylic acid or abscisic acid.