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

摘要

Three clonal lines of oregano (Origanum vulgare) were established for investigating the possible link between de novo synthesis of proline and the phenylpropanoid pathway. Pseudomonas was used to inoculate the otherwise sterile micropropagated oregano shoots to stimulate a defence response. Oregano clones, like other plants, carry out an elicitor-mediated defence response by inducing the phenylpropanoid pathway. Free phenolics and rosmarinic acid are produced via this pathway. Free proline, rosmarinic acid, and free phenolics in oregano shoots were measured. The induced higher levels of rosmarinic acid in some Pseudomonas inoculated clones and at several stages were often correlated to higher levels of proline in those same clones. No conclusive link between free phenolics and free proline levels was found. Clonal line O-4 appeared to be the best one for investigating the role of proline-linked pentose phosphate pathway in regulating rosmarinic acid synthesis.