Preliminary Study of the Monoterpene Response of Three Pines to Ophiostoma clavigerum (Ascomycetes - Ophiostomatales) and Two Chemical Elicitors

1991

S. 377-388

2 Abb., 2 Tab., 30 Lit. Ang.

Unselbständiges Werk

200041349

Annales des Sciences Forestieres 1991 ; 48,Nr. 4, S. 377-388

The monoterpene response of phloem and sapwood of individual pines belonging to 3 species (Pinus contorta, Pinus ponderosa and Pinus monticola) to inoculation with Ophiostoma clavigerum and injection with chitosan, a proteinase inhibitor-inducing factor and a control buffer, was investigated quantitatively and qualitatively. The total quantity of monoterpene in the reactive tissues increased with each treatment but to different levels. In each tree, the monoterpene composition of the reactive tissues differed from that of the unwounded tissues, but was the same whatever the treatment, even in the case of an injection with buffer control. In addition, phloem and sapwood responses were qualitatively identical although constitutive compositions differed greatly. The composition of reactive tissues was not very different fromthat of unwounded sapwood. The direction of variation of each monoterpene from unwounded to reactive tissues differed according to the particular tree. Only phellandrene + limonene reacted consistently. From these results we cannot conclude that chitosan is a natural elicitor, and the non-specificity of the response for the aggression favors the hypothesis that an elicitor originates from the tree itself. Because of this non- specificity, and the fact that the three trees responded in a qualitatively different manner, we suggest that the qualitative monoterpene response of the tree is not adapted to any specific aggressor even though these trees are usually hosts of the same bark beetle-fungus complex. Thus, the role of monoterpenes in the induced defensive response is very likely a quantitative and dose-dependent relationship.