A rare major plant QTL determines non-responsiveness to a gall-forming insect in willow

Höglund, SolveigSwedish University of Agricultural Sciences,Sveriges lantbruksuniversitet,Institutionen för ekologi,Department of Ecology,Department of Ecology, Swedish University of Agricultural Sciences (författare)

Growth and defence are plant traits that determine attack success by sessile herbivorous insects. Models of plant resistance suggest induced resistance to be an especially important mechanism in growth-dominated plant species. Little is known, however, about the effects of absence of induced responses as an alternative resistance mechanism. Large genetically based intraspecific variation in resistance (neonate larval mortality) occurs in Salix viminalis against the gall midge Dasineura marginemtorquens. In certain resistant genotypes, larval mortality is associated with formation of necrotic lesions and biochemical changes commonly found in hypersensitive response (HR). More detailed studies, however, have shown that resistance can occur without HR symptoms. By means of a quantitative trait locus (QTL) analysis, this study tested whether (1) resistance is caused by the HR or (2) by the failure of the midge to initiate a gall (non-responsiveness). One QTL explained 68 and 18 % of the variation in resistance in the experimental population during 2 years of investigation. Co-location of QTLs for resistance and HR was found in only one of the years, i.e. when HR was suppressed. The data suggest that the mechanism of resistance involves non-responsiveness, implying that the insect starves to death due to lack of resources. Such symptomless defence may be more important than previously thought because it is difficult to observe in nature.

Rönnberg Wästljung, Ann-ChristinSwedish University of Agricultural Sciences,Sveriges lantbruksuniversitet,Institutionen för växtbiologi,Department of Plant Biology,Department of Plant Biology and Forest Genetics, Swedish University of Agricultural Sciences(Swepub:slu)48124 (författare)
Lagercrantz, UlfUppsala universitet,Växtekologi och evolution(Swepub:uu)ullag839 (författare)
Larsson, StigSwedish University of Agricultural Sciences,Sveriges lantbruksuniversitet,Institutionen för ekologi,Department of Ecology,Department of Ecology, Swedish University of Agricultural Sciences(Swepub:slu)48601 (författare)
Sveriges lantbruksuniversitetInstitutionen för ekologi (creator_code:org_t)
Sveriges lantbruksuniversitet

Ingår i:Tree Genetics & Genomes: Springer Science and Business Media LLC8:5, s. 1051-10601614-29421614-2950

Av författaren/redakt...: Höglund, Solveig; Rönnberg Wästlju ...; Lagercrantz, Ulf; Larsson, Stig

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