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Costs of resistance to fungal pathogens in genetically modified wheat


Zeller, Simon L; Kalinina, Olena; Schmid, Bernhard (2013). Costs of resistance to fungal pathogens in genetically modified wheat. Journal of Plant Ecology, 6(1):92-100.

Abstract

Aims: Many resistance genes against fungal pathogens show costs of resistance. Genetically modified (GM) plants that differ in only one or a few resistance genes from control plants present ideal systems for measuring these costs in the absence of pathogens.
Methods: To assess the ecological relevance of costs of pathogen resistance, we grew individual plants of four transgenic spring wheat lines in a field trial with three pathogen levels and varied the genetic diversity of the crop.
Important Findings: We found that two lines with a Pm3b transgene were more resistant to powdery mildew than their sister lines of the variety Bobwhite, whereas lines with chitinase (A9) or chitinase and glucanase (A13) transgenes were not more resistant than their mother variety Frisal. Nevertheless, in the absence of the pathogen, both the GM lines of Bobwhite as well as those of Frisal performed significantly worse than their controls, i.e. Pm3b#1 and Pm3b#2 had 39% or 53% and A9 and A13 had 14% or 23% lower yields. In the presence of the pathogen, all GM lines except Pm3b#2 could increase their yields and other fitness-related traits, reaching the performance levels of the control lines. Line Pm3b#2 seemed to have lost its phenotypic plasticity and had low performance in all environments. This may have been caused by very high transgene expression. No synergistic effects of mixing different GM lines with each other were detected. This might have been due to high transgene expression or the similarity between the lines regarding their resistance genes.
We conclude that costs of resistance can be high for transgenic plants with constitutive transgene expression and that this can occur even in cases where the non-transgenic control lines are already relatively resistant, such as in our variety Frisal. Transgenic plants could only compete with conventional varieties in environments with high pathogen pressure. Furthermore, the large variability among the GM lines, which may be due to unpredictable transgene expression, suggests that case-by-case assessments are necessary to evaluate costs of resistance.

Abstract

Aims: Many resistance genes against fungal pathogens show costs of resistance. Genetically modified (GM) plants that differ in only one or a few resistance genes from control plants present ideal systems for measuring these costs in the absence of pathogens.
Methods: To assess the ecological relevance of costs of pathogen resistance, we grew individual plants of four transgenic spring wheat lines in a field trial with three pathogen levels and varied the genetic diversity of the crop.
Important Findings: We found that two lines with a Pm3b transgene were more resistant to powdery mildew than their sister lines of the variety Bobwhite, whereas lines with chitinase (A9) or chitinase and glucanase (A13) transgenes were not more resistant than their mother variety Frisal. Nevertheless, in the absence of the pathogen, both the GM lines of Bobwhite as well as those of Frisal performed significantly worse than their controls, i.e. Pm3b#1 and Pm3b#2 had 39% or 53% and A9 and A13 had 14% or 23% lower yields. In the presence of the pathogen, all GM lines except Pm3b#2 could increase their yields and other fitness-related traits, reaching the performance levels of the control lines. Line Pm3b#2 seemed to have lost its phenotypic plasticity and had low performance in all environments. This may have been caused by very high transgene expression. No synergistic effects of mixing different GM lines with each other were detected. This might have been due to high transgene expression or the similarity between the lines regarding their resistance genes.
We conclude that costs of resistance can be high for transgenic plants with constitutive transgene expression and that this can occur even in cases where the non-transgenic control lines are already relatively resistant, such as in our variety Frisal. Transgenic plants could only compete with conventional varieties in environments with high pathogen pressure. Furthermore, the large variability among the GM lines, which may be due to unpredictable transgene expression, suggests that case-by-case assessments are necessary to evaluate costs of resistance.

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Additional indexing

Item Type:Journal Article, refereed, original work
Communities & Collections:07 Faculty of Science > Institute of Evolutionary Biology and Environmental Studies
Dewey Decimal Classification:570 Life sciences; biology
590 Animals (Zoology)
Uncontrolled Keywords:powdery mildew; resistance genes; transgene expression; transgene stacking; yield
Language:English
Date:2013
Deposited On:16 Aug 2013 08:58
Last Modified:05 Apr 2016 16:45
Publisher:Oxford University Press
ISSN:1752-9921
Additional Information:This is a pre-copy-editing, author-produced PDF of an article accepted for publication in Journal of Plant Ecology following peer review. The definitive publisher-authenticated version Zeller, Simon L; Kalinina, Olena; Schmid, Bernhard (2013). Costs of resistance to fungal pathogens in genetically modified wheat. Journal of Plant Ecology, 6(1):92-100 is available online at: http://jpe.oxfordjournals.org/content/6/1/92
Free access at:Publisher DOI. An embargo period may apply.
Publisher DOI:https://doi.org/10.1093/jpe/rts013

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