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Effects of nutrient variability on the genetic-based resistance of Eucalyptus globulus to a mammalian herbivore and on plant defensive chemistry

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O'Reilly-Wapstra, JM and Potts, BM and McArthur, C and Davies, NW (2005) Effects of nutrient variability on the genetic-based resistance of Eucalyptus globulus to a mammalian herbivore and on plant defensive chemistry. Oecologia, 142 (4). pp. 597-605. ISSN 0029-8549

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Abstract

Abstract Plant resistance to herbivores can be influenced
not only by the independent effects of plant genotype
and environmental variation, but by interactions between
the two. The main aim of this study was to assess
the effects of environmental variability (nutrient treatment)
on the known genetic-based expression of resistance
and defensive chemistry of Eucalyptus globulus to
browsing by the generalist mammalian herbivore Trichosurus
vulpeculaf. In a captive feeding trial, we measured
intake of seedlings from one relatively resistant
(Blue Gum Hill) and one relatively susceptible (St Helens)
population of E. globulus grown under two nutrient
treatments (no fertiliser, plus fertiliser). There was a
significant genotype·fertiliser interaction effect on intake
of E. globulus foliage by T. vulpecula, and the predicted
genetic-based resistance of the two populations
was expressed only for the non-fertilised treatment.
Expression of resistance largely reflected the combined
and inverse effects of nitrogen and condensed tannin
concentrations. The expression of plant secondary
metabolite concentration differed between compounds,
but in all cases the effects of plant genotype and fertiliser
treatment were independent. The formylated phloroglucinol
compounds differed significantly between
genotypes but not between fertiliser treatments. In
contrast, the effect of plant genotype on the expression
of condensed tannins was weak but they were significantly
reduced by fertiliser. Essential oils were influenced
by both plant genotype and fertiliser treatment and were
significantly higher in the fertilised seedlings than in the
non-fertilised seedlings. This study highlights interactive
effects of plant genotype and environment in influencing
the phenotypic expression of resistance in a eucalypt
species to a mammalian browser. It also demonstrates
that this interactive effect is the net result of independent
effects of genotype and environment on plant chemistry
and finally, that different groups of compounds within a
plant can respond very differently to variation in environmental
conditions.

Item Type: Article
Keywords: Environmental variation Plant resistance Trichosurus vulpecula Plant secondary compounds Eucalypt
Journal or Publication Title: Oecologia
Page Range: pp. 597-605
ISSN: 0029-8549
Identification Number - DOI: 10.1007/s00442-004-1769-y
Additional Information:

BM Potts. The original publication is available at www.springerlink.com

Date Deposited: 22 Sep 2008 06:19
Last Modified: 18 Nov 2014 03:49
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