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Induced responses in willow determine feeding success of a gall-forming insect

Höglund, Solveig (2010). Induced responses in willow determine feeding success of a gall-forming insect. Diss. (sammanfattning/summary) Uppsala : Sveriges lantbruksuniv., Acta Universitatis Agriculturae Sueciae, 1652-6880 ; 2010:82
ISBN 978-91-576-7527-9
[Doctoral thesis]

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In the willow Salix viminalis L. (Salicaceae), growth and defence are key responses determining feeding success of the gall midge Dasineura marginemtorquens Bremi (Diptera: Cecidomyiidae). The interaction includes induced growth (gall formation), and induced defence (hypersensitive response, HR). Salix viminalis exhibits large genotypic variation in resistance (larval mortality) against D. marginemtorquens. This thesis focuses on testing hypotheses developed from field observations of interactions between the willow and the gall midge. A specific aim was to gain insight into the mechanism(s) of resistance. Combined greenhouse and field experiments were used to test whether abiotic factors induce susceptibility in otherwise resistant genotypes at the time of gall initiation. The results suggest that plasticity in plant resistance is linked to ambient conditions, probably light. Resistance was associated with HR, but to different degrees among willow genotypes. Hydrogen peroxide, a marker of HR, was induced in genotypes expressing HR but not in resistant genotypes not showing symptoms. The genetic architecture of plant traits that determine larval mortality and HR was investigated by means of a QTL analysis. The presence of one particular allele at one single locus was enough to determine life or death of the gall midge. The defence hypothesis was not supported when examining the homologous region in the poplar genome. However, an auxin gene was located within the QTL area, lending some support for the starvation and anti-manipulation hypothesis. The place of birth (leaf position) was found to be important for insect fitness, and the quality of a gall seemed to be associated with the duration of the site as a resource sink. In conclusion, data suggest that the mechanism of resistance involves anti-manipulation of growth rather than defence. Such, nonreactivity genes may have pleiotropic effects, and the frequency of genes insensitive to manipulation might be restricted in nature due to selection compared with the gall stimulus phenotype.

Authors/Creators:Höglund, Solveig
Title:Induced responses in willow determine feeding success of a gall-forming insect
Series Name/Journal:Acta Universitatis Agriculturae Sueciae
Year of publishing :2010
Number of Pages:34
ALLI. Höglund S, Larsson S (2005). Abiotic induction of susceptibility in insect-resistant willow. Entomologia Experimentalis et Applicata vol(115), 89-96. II. Höglund S, Larsson S, Wingsle G (2005). Both hypersensitive and non-hypersensitive responses are associated with resistance in Salix viminalis against the gall midge Dasineura marginemtorquens. Journal of Experimental Botany vol (56) no 422, 3215-3222. III. Höglund S, Rönnberg-Wästljung A-C, Lagercrantz U, Larsson S A rare major plant QTL determines resistance against a gall-forming insect in willow (Submitted manuscript). IV. Höglund S. Birthplace determines fitness of a galling insect on willow. (manuscript)
Place of Publication:Uppsala
ISBN for printed version:978-91-576-7527-9
Publication Type:Doctoral thesis
Full Text Status:Public
Agrovoc terms:salix viminalis, dasineura, gall causing insects, plant response, plant animal relations, pest resistance, growth, quantitative trait loci
Keywords:Salix viminalis, Dasineura marginemtorquens, gall midge, HR, fitness, QTL, developmental resistance, hypersensitive response, defence, growth, plant-insect interaction.
Permanent URL:
ID Code:2405
Department:(NL, NJ) > Dept. of Ecology
(S) > Dept. of Ecology
Deposited By: Solveig Höglund
Deposited On:19 Nov 2010 00:00
Metadata Last Modified:02 Dec 2014 10:18

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