ANALYSIS OF THE JASMONATE AND WOUND INDUCIBLE FORM OF MYROSINASE ASSOCIATED PROTEIN IN BRASSICA NAPUS
E ANDREASSONl, J TAIPALENSUU2, L RASK3 and J MEIJERl
Dept. of Plant Biology, Uppsala Genetic Center, SLU, SE-750 07 Uppsala, Sweden;
l Swedish Board of Agriculture, SE-551 82 Jonkoping, Sweden ;2 Dept. of Medical and Physiological Chemistry, Biomedical Center, Uppsala University, SE-751 23 Uppsala, Sweden.
Background and objectives
Wounding of plants triggers a number of different defense reactions in order to develop resistance throughout the plant. Jasmonic acid seems to be involved in the signal transduction pathway elicited by wounding. One of the proteins that is transcriptionally activated as a result of this signaling is a myrosinase associated protein (MyAP). The myrosinase-glucosinolate system is present in members of the Brassicaceae  where the enzyme myrosinase acts on glucosinolates to produce toxic compounds which may deter insects and pathogens. Certain myrosinases are present in complexes with other proteins such as the myrosinase associated protein (MyAP). We are interested in the function and regulation of myrosinase associated proteins and have focused our studies on oilseed rape (Brassica napus). Two forms of MyAP genes have been cloned, one which is wound-inducible and present in vegetative tissues and one which is seed specific.
Results and Conclusions
The amount of one MyAP transcript is rapidly unregulated by wounding, jasmonate and abscissic acid, but the wound response is desensitized by salicylic acid . The wound response of MyAP is systemic and encountered in most cells of the primary and secondary true leaves in young plants. The genomic clone of the induced form of MyAP in Brassica napus has been isolated. It contains four introns and an untranslated 5' region of 33/35 base pairs. Two kilobases of the promoter have been sequenced and putative regulatory elements have been identified. One G-box and several G-box like elements as well as other sequence motifs that are similar but not identical to elements described in inducible promoters, have been encountered in the MyAP promoter. MyAP promoter-GUS transformants of Arabidopsis thaliana show responsiveness to jasmonate and wounding. The jasmonate induction is approximately ten times higher in true leaves than in seedlings, indicating the potential value of analysis of deletion mutants. Currently, protein accumulation after induction in antisense plants constructs and also the relationship between MyAP expression and pathogen attack are being investigated.
This study was supported by the Swedish Research Council for Forestry and Agriculture and the Foundation for Strategic Research.
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