The effect of methyl-jasmonate and wounding on pinoresinol-lariciresinol reductase gene expression in flax Linum usitatissimum

Pinoresinol lariciresinol reductase (PLR) enzymes catalyse biosynthesis of lignans, phenolic compounds which are being more and more appreciated for their health benefits in human. Different lignans are accumulated in high concentrations in seed coats and other parts of flax (Linum usitatissimum) plant, from which two PLR enzymes of opposite enantiospecificity have been isolated. While LuPLR1 catalyses the biosynthesis of (+)-secoisolariciresinol, which is shown to have chemopreventive effects against hormone-dependent cancers, the roles of recently isolated LuPLR2 and products of its activity are not completely elucidated. The aim of this work was to get insights into LuPLR2 gene expression regulation via treatments with methyl jasmonate, and wounding, since lignans are supposed to be involved in plant defence mechanisms. The main results show significant increase of LuPLR2 gene expression due to methyl jasmonate treatment in L. usitatissimum cell suspension, hairy roots, and leaves, but not in seeds. Wounding of leaves on greenhouse-grown plants resulted in rapid and transient induction of LuPLR2 expression. Functional analysis of LuPLR2 promoter via GUS and MUG assays showed activity of promoter in callus tissue for each construct and in xylem tissue of leaves and stems. All data are to be confirmed by quantitative PCR analysis to get more precise information. Future work will also include qualitative / quantitative analyses of lignans in treated and control material and the study of the consequences of LuPLR2 down-regulation on lignan biosynthesis in plants transformed with RNAi PLR2 construct. Further analyses of LuPLR2 promoter putative cis regulatory elements will be performed to obtain more information about regulation of its transcriptional activity