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New Phytol

Title:		Beetle grazing reduces natural infection of Rumex obtusifolius by fungal pathogens
Author(s):		Hatcher PE; Paul ND;
Address:		"1 Department of Agricultural Botany, School of Plant Sciences, The University of Reading, 2 Earley Gate, Whiteknights, Reading RG6 6AU, UK"
Journal Title:		New Phytol
Year:		2000
Volume:		146
Issue:		2
Page Number:		325 - 333
DOI:		10.1046/j.1469-8137.2000.00646.x
ISSN/ISBN:		1469-8137 (Electronic) 0028-646X (Linking)
Abstract:		"In previously reported laboratory experiments, infection of Rumex obtusifolius by the rust fungus Uromyces rumicis was decreased on leaves which had prior herbivory by the beetle Gastrophysa viridula. In this paper we investigate whether this interaction is robust for natural infection by a variety of fungi in field experiments carried out in spring and autumn with plants given different levels of nitrogen fertilization. Grazing by G. viridula led to a decrease in lesion density of Ramularia rubella and Venturia rumicis in the spring and V. rumicis and U. rumicis in the autumn experiment. For V. rumicis and U. rumicis significant reductions in lesion density occurred on the undamaged leaves of damaged plants, compared with similar leaves on undamaged plants, suggesting systemic induced resistance. This induced resistance was usually independent of the amount of nitrogen fertilization, although the inhibitory effect of grazing on R. rubella in the spring and V. rumicis in the autumn experiment was enhanced by increasing nitrogen fertilization and was inhibited by increasing nitrogen fertilization for V. rumicis in the spring. In both experiments, the lesion density of V. rumicis was greater on leaves on which R. rubella was also present, and the presence of U. rumicis in the autumn experiment was linked to a similar but greater effect on V. rumicis lesion density. We found no evidence of induced resistance by fungi against fungi in these experiments. We highlight the complex interactions between inhibitory and facilitatory processes acting on leaf fungal infection. These results are compared with the proposed molecular mechanisms of induced resistance(s) and we consider the benefits of closer integration between molecular and ecological investigations of induced resistances that occur in the field"
Keywords:		fungal infection herbivory necrotrophs nitrogen fertilization rust fungi systemic acquired resistance tripartite interactions;
Notes:		"PubMed-not-MEDLINEHatcher, P E Paul, N D eng Review England 2000/05/01 New Phytol. 2000 May; 146(2):325-333. doi: 10.1046/j.1469-8137.2000.00646.x"