© 1994 Heron Publishing—Victoria, Canada
Influence of water relations on Quercus cerris–Hypoxylon mediterraneum interaction: a model of drought-induced susceptibility to a weakness parasite
A. Vannini (1) and R. Valentini (2)
1. Department of Plant Protection, University of Tuscia, Via S. Camillo de Lellis, 01100 Viterbo, Italy / 2. Department of Forestry and Environmental Sciences, University of Tuscia, Via S. Camillo de Lellis, 01100 Viterbo, Italy / Received February 2, 1993
Summary
The association between water stress and susceptibility of Quercus cerris to the fungal parasite Hypoxylon mediterraneum was studied in field-grown trees and greenhouse-grown seedlings. Susceptibility of Q. cerris to the fungus, expressed as extension of wood discolorations, increased in field-grown trees during drought and increased
in greenhouse-grown seedlings in response to limited water supply. In both seedlings and trees, spread of the fungus in the
vascular system was higher when leaf water potentials were low than when leaf water potentials were high, and was significantly
correlated to loss of hydraulic conductivity of xylem. The presence of the fungus in the xylem suggests that H. mediterraneum could use embolized vessels to spread in the host.
Keywords:
fungus, hydraulic conductivity, vascular system, water stress, xylem.
