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Non-target Effects of Genetically Modified Trees
Umeå University, Faculty of Science and Technology, Ecology and Environmental Science.
2007 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

To date, few studies have focused on the effects of genetically modified trees (GM trees) on the environment. One concern with GM trees is that they may have unanticipated effects on non-target organisms, i.e. effects on organisms that are not direct targets of the genetically modified trait. The main objective of this thesis was to study potential non-target effects from the interaction between GM trees and natural enemies, including phytopathogens and herbivorous insects.

To study this I used a system consisting of GM trees featuring changes in growth-related characteristics, and naturally occurring enemies. The GM trees used were the aspen hybrids Populus tremula x tremuloides: one unmodified wild type clone T89 (control) and transgenic lines with altered expression of gibberellin (GA 20-oxidase), sucrose (SPS) or pectin (PME); and Populus tremula x alba: one unmodified wild type clone INRA 717-1-B4 (control) and lines modified to suppress the activity of the enzymes in the lignin biosynthetic pathway, i.e. CAD, COMT, CCR or CCoAOMT. The natural enemies used were the parasitic phytopathogens Melampsora pinitorqua, M. populnea and Venturia tremulae, and the herbivorous leaf-beetle Phratora vitellinae. To address this question inoculation experiments, feeding preference experiments, analyses of secondary chemistry and field inventories were performed.

The results of the studies showed that the GM trees significantly affected the interaction with the natural enemies, both in the laboratory as well as in the field. For instance, both M. pinitorqua and V. tremulae showed an altered disease incidence on the GM trees of P. tremula x tremuloides compared to the unmodified wild type T89, where all tested transgenic lines exhibited altered susceptibility to the pathogens. However, there were also differences in aggressiveness to the aspens depending on pathogen population. The results from the field inventory showed that lines within all tested transgenic construct, COMT, CAD, CCoAOMT and CCR of P. tremula x alba differed significantly from the wild type INRA 717-1-B4 in susceptibility to M. populnea. In addition, the susceptibility to the rust also differed significantly between lines carrying the same transgenic constructs. Furthermore, we found that overexpression of SPS in P. tremula x tremuloides, unintentionally induced changes in plant secondary chemistry, where the GM-line SPS33A exhibited the largest deviation from the wild type T89 in contents of plant phenolics and nitrogen, and that these changes coincide with a concurrent decrease in herbivory by P. vitellinae on this line.

I argue that the altered interactions are the result of physiological changes in the trees. They can originate from direct effects i.e. altered expression of the modified trait, indirect effects of the genetic modification process e.g. pleiotropy, or effects from the transformation process e.g. position effects, to which the tested natural enemies respond.

The result stresses the importance of further research on the causes and mechanisms responsible for the altered interaction between GM trees and non-target organisms, as well as evaluating the potential environmental effects of cultivation of GM trees in the field. Such research will require collaboration between researchers from different disciplines, such as plant ecology and physiology, functional genomics, proteomics and metabolomics.

Place, publisher, year, edition, pages
Umeå: Ekologi, miljö och geovetenskap , 2007. , 27 p.
Keyword [en]
Genetically modified, GM trees, secondary metabolism, phytochemistry, Populus, transgenic, non-target effects, natural enemies, plant-pathogen/herbivore interaction, environmental effects, parasitic fungi, herbivorous insect
National Category
Ecology
Identifiers
URN: urn:nbn:se:umu:diva-1348ISBN: 978-91-7264-391-8 (print)OAI: oai:DiVA.org:umu-1348DiVA: diva2:140724
Public defence
2007-10-06, Lilla Hörsalen, KBC, Umeå universitet, Umeå, 10:00 (English)
Opponent
Supervisors
Available from: 2007-09-14 Created: 2007-09-14 Last updated: 2009-08-31Bibliographically approved
List of papers
1. Testing the effect of genetically modified hybrid aspen Populus tremula x tremuloides on the interaction with the non-target pathogen Melampsora pinitorqua.
Open this publication in new window or tab >>Testing the effect of genetically modified hybrid aspen Populus tremula x tremuloides on the interaction with the non-target pathogen Melampsora pinitorqua.
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Article in journal (Refereed) Submitted
Identifiers
urn:nbn:se:umu:diva-2540 (URN)
Available from: 2007-09-14 Created: 2007-09-14Bibliographically approved
2. Genetically engineered aspen (Populus tremula x tremuloides) alters its interactions with the non-target pathogen Venturia tremulae.
Open this publication in new window or tab >>Genetically engineered aspen (Populus tremula x tremuloides) alters its interactions with the non-target pathogen Venturia tremulae.
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Article in journal (Refereed) Accepted
Identifiers
urn:nbn:se:umu:diva-2541 (URN)
Available from: 2007-09-14 Created: 2007-09-14Bibliographically approved
3. Unintentional changes of defence traits in GM trees can influence plant-herbivore interactions
Open this publication in new window or tab >>Unintentional changes of defence traits in GM trees can influence plant-herbivore interactions
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2007 (English)In: Basic and Applied Ecology, Vol. 8, no 3, 434-443 p.Article in journal (Refereed) Published
Abstract [en]

GM trees hold promises of increased quality and yield and reduced use of herbicides and pesticides but could also have ecological consequences. We investigated whether modification of a non-defensive trait unintentionally influenced plant traits important for plant-herbivore interactions. We found that over-expression of sucrose phosphate synthase (SPS), which is known to increase mesophyll sucrose content and biomass production in GM aspens, also unintentionally induced changes in the concentration of plant phenolics and nitrogen. One of the GM lines, SPS33A, had higher concentrations of salicin, tremuloidin, condensed tannins and nitrogen and lower concentrations of coumaric acid and four flavonoids compared with the isogenic wild type. Line SPS33A was also utilized less by the leaf-beetle Phratora vitellinae than the isogenic wild type. Ecological consequences such as this are not specific to GM trees or GM plants but can occur as a result of the introduction of all introduced new varieties of crops or trees. Nevertheless, the results underline the need to consider these unexpected effects when evaluating both the potential benefits and the potential risks with GM plants, and highlight the need to establish and implement comprehensive product-by-product evaluation protocols for GM plants.

Identifiers
urn:nbn:se:umu:diva-10446 (URN)doi:10.1016/j.baae.2006.09.001 (DOI)
Available from: 2008-09-11 Created: 2008-09-11 Last updated: 2015-04-29Bibliographically approved
4. Field survey of genetically modified trees (Populus tremula x alba) with altered lignification unveils altered susceptibility to the non-target pathogen Melampsora populnea.
Open this publication in new window or tab >>Field survey of genetically modified trees (Populus tremula x alba) with altered lignification unveils altered susceptibility to the non-target pathogen Melampsora populnea.
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Manuscript (Other academic)
Identifiers
urn:nbn:se:umu:diva-2543 (URN)
Available from: 2007-09-14 Created: 2007-09-14 Last updated: 2010-01-13Bibliographically approved

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