A model for involvement of proline during Pseudomonas-mediated stimulationof rosmarinic acid levels in oregano shoot clones

We have established three clonal lines of oregano (Origanum vulgare) for th e purpose of investigating the possible link between de nova synthesis of p roline and the phenylpropanoid pathway. We used Pseudomonas as inoculation in the otherwise sterile micropropagated oregano shoots to stimulate a defe nse response. Oregano clones, like other plants, carry out an elicitor-medi ated defense response by inducing the phenylpropanoid pathway. Free phenoli cs and rosmarinic acid are produced via this pathway. We measured free prol ine, rosmarinic acid, and free phenolics in oregano shoots. We found that t he induced higher levels of rosmarinic acid in some Pseudomonas inoculated clones and at several stages is often correlated to higher levels of prolin e in those same clones. We found no conclusive link between free phenolics and free proline levels. From this study clonal line O-4 appeared to be the best line to investigate the role of proline-linked pentose phosphate path way in regulating rosmarinic acid synthesis.