Expression of lipoxygenase in wounded tubers of Solanum tuberosum L.

A lipoxygenase cDNA clone from Solanum tuberosum L. was analyzed to study the role of lipoxygenases in potato development and wound response. Sequence analysis and comparison of the deduced amino acid sequence revealed high homology to other plant lipoxygenases. Expression of the cDNA sequences in Escherichia coli and subsequent analysis of bacterial protein extracts showed lipoxygenase activity using linoleic, linolenic, or arachidonic acid as substrates. Transcripts encoding the potato lipoxygenase were most abundant in tuber tissue, lower in roots, and hardly detectable in leaves, petioles, and stems. The induction of lipoxygenase expression in tubers by wounding was dependent on various parameters. Whereas lipoxygenase transcript levels increased in discs from stored tubers incubated under aerobic conditions, tubers taken from a growing plant did not accumulate lipoxygenase transcripts in response to wounding. Incubation of tuber discs in buffer did not lead to an increase in lipoxygenase RNA levels; however, methyl jasmonate stimulated lipoxygenase expression after 24 h in stored tubers. Proteinase inhibitor II mRNAs decreased in stored tubers as well as in discs from growing tubers.