OLIGOPEPTIDE ELICITOR-MEDIATED DEFENSE GENE ACTIVATION IN CULTURED PARSLEY CELLS

We have used suspension cultured parsley cells (Petroselinum crispum) and an oligopeptide elicitor derived from a surface glycoprotein of th e phytopathogenic fungus Phytophthora megasperma f.sp. glycinea to stu dy the signaling pathway from elicitor recognition to defense gene act ivation. Immediately after specific binding of the elicitor by a recep tor in the plasma membrane, large and transient increases in several i norganic ion fluxes (Ca2+, H+, K+, Cl-) and H2O2 formation are the fir st detectable plant cell responses, These are rapidly followed by tran sient changes in the phosphorylation status of various proteins and by the activation of numerous defense-related genes, concomitant with th e inactivation of several other, non-defense-related genes. A great di versity of cis-acting elements and trans-acting factors appears to be involved in elicitor-mediated gene regulation, similar to the apparent ly complex nature of the signal transduced intracellularly. With few e xceptions, all individual defense responses analyzed in fungus-infecte d parsley leaves have been found to be closely mimicked in elicitor-tr eated, cultured parsley cells, thus validating the use of the elicitor /cell culture system as a valuable model system for these types of stu dy.