Ecological interactions between herbivores and silver birch and aspen trees genetically modified for fungal disease resistance
Vihervuori L. (2015). Ecological interactions between herbivores and silver birch and aspen trees genetically modified for fungal disease resistance. https://doi.org/10.14214/df.196
Abstract
Many risks and environmental concerns have been linked with the cultivation of genetically modified (GM) trees. Among the most frequently mentioned risks are the unintentional/pleiotropic effects of transgenes on organisms or plant properties that are not the targets of genetic modification. Risks in forest ecosystems are difficult to predict, due to the long life cycles of trees and their complex ecological interactions. This thesis is focused on the interactions between insect and mammal herbivores and transgenic trees. The studied silver birch (Betula pendula Roth) carried a sugar beet chitinase IV gene and the aspen and hybrid aspen (Populus sp.) carried a pine pinosylvin synthase gene, both aiming to improve the trees’ resistance to fungal diseases, but also potentially affecting insect and mammal herbivores. Tree growth and quality, and insect density and composition were studied during the field trial. In feeding experiments, the palatability of transgenic trees was studied in the feeding experiments using the lepidopteran herbivores rusty tussock moth and buff-tip (Orgyia antiqua L., Phalera bucephala L.) and the mammalian herbivores mountain hare and roe deer (Lepus timidus L., Capreolus capreolus L.). The studies revealed that sugar beet chitinase IV caused unintentional effects on silver birch: the transgenic trees were smaller and their red leaf colour indicated stress. There were differences in herbivore pressure between transgenic and wild-type birches: GM trees had a higher aphid density but a lower diversity of insect species and visible leaf damages. The relative growth rate of O. antiqua on transgenic birches was lower in comparison to wild-type birches. No difference in the palatability to mammals was found between transgenic and wild-type trees. The results suggest that the impact on herbivores is species- dependent. The pleiotropic effects of the transgenes affecting plant-herbivore interaction can explain these impacts. These results should be taken into account when considering the biosafety of GM trees.
Keywords
transgenic tree;
cafeteria trial;
field trial;
herbivory;
non-target effect;
chitinase;
pinosylvin synthase
Published 17 June 2015
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Available at https://doi.org/10.14214/df.196 | Download PDF
Original articles
Pasonen H.-L., Vihervuori L., Seppänen S.-K., Lyytikäinen-Saarenmaa P., Ylioja T., von Weissenberg K., Pappinen A. (2008). Field performance of chitinase transgenic silver birch (Betula pendula Roth): growth and adaptive traits. Trees - Structure and Function 22: 413–421.
https://doi.org/10.1007/s00468-007-0202-7
Vihervuori L., Pasonen H.-L., Lyytikäinen-Saarenmaa P. (2008). Density and composition of an insect population in a field trial of chitinase transgenic and wild-type silver birch (Betula pendula)
clones. Environmental Entomology 37: 1582–1591.
https://doi.org/10.1603/0046-225X-37.6.1582
Vihervuori L., Lyytikäinen-Saarenmaa P., Lu J., Pasonen H.-L. (2013). Effects of sugar beet chitinase IV on lepidopteran herbivores feeding on transgenic birch (Betula pendula). European Journal of Entomology 110: 253–262.
https://doi.org/10.14411/eje.2013.038
Vihervuori L., Lyytikäinen-Saarenmaa P., Tuomikoski E., Luoma M., Niemelä P., Pappinen A., Pasonen H.-L. (2012). Palatability of transgenic birch and aspen to roe deer and mountain hare.
Biocontrol Science and Technology 22: 1167–1180.