Role of Jasmonates in the Elicitor- and Wound-Inducible Expression of Defense Genes in Parsley and Transgenic Tobacco.

Jasmonates have been proposed to be signaling intermediates in the wound and/or elicitor-activated expression of plant defense genes. We used parsley (Petroselinum crispum) cell cultures and transgenic tobacco (Nicotiana tabacum) plants expressing 4CL1-GUS gene fusions to investigate the potential role played by jasmonates in mediating the wound and/or elicitor activation of phenylpropanoid and other defense-related genes. Jasmonates and [alpha]-linolenic acid strongly induced the expression of 4CL in a dose-dependent manner in parsley cells; methyl jasmonate also activated the coordinate expression of other phenylpropanoid genes and the accumulation of furanocoumarin phytoalexins. However, the response of the cells to optimal methyl jasmonate concentrations was distinct quantitatively and qualitatively from the response of elicitor-treated cells. In transgenic tobacco wound-inducible tobacco 4CL genes and a 4CL1 promoter-GUS transgene were responsive to jasmonates and [alpha]-linolenic acid in a dose-dependent manner. Pre-treatment of parsley cells or tobacco leaves with a lipoxygenase inhibitor reduced their responsiveness to the elicitor and to wounding. These results show that the elicitor response in parsley cells can be partially mimicked by jasmonate treatment, which supports a role for jasmonates in mediating wound-induced expression of 4CL and other phenylpropanoid genes.