A GLYCOPROTEIN FROM CERATOCYSTIS-FIMBRIATA F SP. PLATANI TRIGGERS PHYTOALEXIN SYNTHESIS IN PLATANUS X ACERIFOLIA CELL-SUSPENSION CULTURES

Treatment of cell-suspension cultures of Platanus x acerifolia with a crude elicitor preparation from Ceratocystis fimbriata f. sp. platani germlings induced the synthesis of the hydroxycoumarin phytoalexins, s copoletin and umbelliferone, and their accumulation in the growth medi um. Only the protein-containing fraction of the culture filtrate was i nvolved in cell response. By ultrafiltration of this last fraction, a major eliciting glycoprotein able to induce 80% coumarin synthesis was isolated. The glycoprotein was substituted by N-glycan(s) containing terminally linked mannose as revealed by lectin immunoblotting. The mo lecular mass of the eliciting compound is 66 kD (SDS-PAGE) and the nat ive conformation was necessary for elicitor recognition by plane tree cells and thereby phytoalexin synthesis. We discuss the possible invol vement of the GP 66 elicitor from the canker stain agent of the plane tree in the activation of the phenolic metabolism of the plant. (C) 19 98 Published by Elsevier Science Ltd. All rights reserved.