Plant fitness assessment for wild relatives of insect resistant crops

Letourneau, Deborah K.; Hagen, Joy A.

doi:10.1051/ebr/2008024

Cited by 8 publications

(8 citation statements)

References 38 publications

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“…2008), as found in other taxa (Hooftman et al. 2005; Letourneau & Hagen 2009). Sunflower crop–wild hybrids can vary greatly from relatively low to comparable fitness with wild plants (Cummings et al.…”

Section: Introductionsupporting

confidence: 71%

Persistence of sunflower crop traits and fitness in Helianthus petiolaris populations

2011

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Transgenic plants have increased interest in the study of crop gene introgression in wild populations. Genes (or transgenes) conferring adaptive advantages persist in introgressed populations, enhancing competitiveness of wild or weedy plants. This represents an ecological risk that could increase problems of weed control. Introgression of cultivar alleles into wild plant populations via crop-wild hybridisations is primarily governed by their fitness effect. To evaluate this, we studied the second generation of seven wild-crop interspecific hybrids between weedy Helianthus petiolaris and cultivated sunflower, H. annuus var. macrocarpus. The second generation comprised open-pollinated progeny and backcrosses to the wild parent, mimicking crosses that occur in natural situations. We compared a number of morphological, life history and fitness traits. Multivariate analysis showed that the parental species H. annuus and H. petiolaris differed in a number of morphological traits, while the second hybrid generation between them was intermediate. Sunflower crop introgression lowered fitness of interspecific hybrids, but fitness parameters tended to recover in the following generation. Relative frequency of wild/weedy and introgressed plants was estimated through four generations, based on male and female parent fitness. In spite of several negative selection coefficients observed in the second generation, introgressed plants could be detected in stands of <100 weedy H. petiolaris populations. The rapid recovery of fecundity parameters leads to prediction that any trait conferring an ecological advantage will diffuse into the wild or weedy population, even if F1 hybrids have low fitness.

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Section: Introductionsupporting

confidence: 71%

Persistence of sunflower crop traits and fitness in Helianthus petiolaris populations

2011

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“…Seed output of wild mustard that survived to maturity was not consistently affected by differential herbivory, with a significant increase in Bt-protected plants only in the last year of our study [46]. Therefore, our results and those of Stewart et al [52] reflect lifetime fitness of B. rapa, including early mortality.…”

Section: Herbivory and Plant Fitnesssupporting

confidence: 63%

“…Whether transgenes stably expressed in cropwild hybrids [47] allow them to compete favorably [41,[48][49][50][51], persist, and spread more rapidly depends critically on the fitness advantage of the introduced resistance trait. Although wild mustard increased fitness overall when protected from the Bt susceptible subset of its herbivores [46], Bt-protected B. rapa was the lesser competitive Brassicaceae in nonagricultural areas with established vegetation. Both the overall fitness advantage of B. rapa plants protected with Bt endotoxins, and the weaker response in established vegetation are similar and complementary to the results of Stewart et al [52] comparing transgenic Bt-Brassica napus and nontransgenic B. napus subjected to a defoliation episode that resulted in a 40%-60% decrease in percent herbivory, through the addition of larval diamondback moth in cultivated and natural vegetation plots.…”

Section: Herbivory and Plant Fitnessmentioning

confidence: 97%

“…Although little is known about R. sativus, tests with R. raphanistrum show that it is unlikely to hybridize with Brassica crops (but see Gueritaine et al [41]). Because crop-to-weed gene flow is highly idiosyncratic and difficult to preclude totally in many regions of the world and for many crop plants, research on the effects of transgenes on natural communities ( [42] and references therein) and field tests where wild relatives of pest-resistant crops occur naturally are needed for risk assessment of transgenic crops [9,12,[43][44][45][46]. Whether transgenes stably expressed in cropwild hybrids [47] allow them to compete favorably [41,[48][49][50][51], persist, and spread more rapidly depends critically on the fitness advantage of the introduced resistance trait.…”

Section: Herbivory and Plant Fitnessmentioning

confidence: 99%

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Plant Fitness Assessment for Wild Relatives of Insect Resistant Bt-Crops

Letourneau

Hagen

2012

Journal of Botany

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When field tests of transgenic plants are precluded by practical containment concerns, manipulative experiments can detect potential consequences of crop-wild gene flow. Using topical sprays of bacterial Bacillus thuringiensis larvicide (Bt) and larval additions, we measured fitness effects of reduced herbivory on Brassica rapa (wild mustard) and Raphanus sativus (wild radish). These species represent different life histories among the potential recipients of Bt transgenes from Bt cole crops in the US and Asia, for which rare spontaneous crosses are expected under high exposure. Protected wild radish and wild mustard seedlings had approximately half the herbivore damage of exposed plants and 55% lower seedling mortality, resulting in 27% greater reproductive success, 14-day longer life-spans, and 118% more seeds, on average. Seed addition experiments in microcosms and in situ indicated that wild radish was more likely to spread than wild mustard in coastal grasslands.

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“…If these two approaches yield similar results, however, data are more likely to be considered robust, and uncertainty reduced. For example, plant fitness consequences of insect-resistance genes in wild relatives of Bt-canola indicate similar patterns for isolated transgenic plants and in situ surrogates [38, 39]. …”

Section: The Limits Of the Classical Risk Paradigmmentioning

confidence: 99%

What Risk Assessments of Genetically Modified Organisms Can Learn from Institutional Analyses of Public Health Risks

Rajan

Letourneau

2012

Journal of Biomedicine and Biotechnology

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The risks of genetically modified organisms (GMOs) are evaluated traditionally by combining hazard identification and exposure estimates to provide decision support for regulatory agencies. We question the utility of the classical risk paradigm and discuss its evolution in GMO risk assessment. First, we consider the problem of uncertainty, by comparing risk assessment for environmental toxins in the public health domain with genetically modified organisms in the environment; we use the specific comparison of an insecticide to a transgenic, insecticidal food crop. Next, we examine normal accident theory (NAT) as a heuristic to consider runaway effects of GMOs, such as negative community level consequences of gene flow from transgenic, insecticidal crops. These examples illustrate how risk assessments are made more complex and contentious by both their inherent uncertainty and the inevitability of failure beyond expectation in complex systems. We emphasize the value of conducting decision-support research, embracing uncertainty, increasing transparency, and building interdisciplinary institutions that can address the complex interactions between ecosystems and society. In particular, we argue against black boxing risk analysis, and for a program to educate policy makers about uncertainty and complexity, so that eventually, decision making is not the burden that falls upon scientists but is assumed by the public at large.

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Plant fitness assessment for wild relatives of insect resistant crops

Cited by 8 publications

References 38 publications

Persistence of sunflower crop traits and fitness in Helianthus petiolaris populations

Persistence of sunflower crop traits and fitness in Helianthus petiolaris populations

Plant Fitness Assessment for Wild Relatives of Insect Resistant Bt-Crops

What Risk Assessments of Genetically Modified Organisms Can Learn from Institutional Analyses of Public Health Risks

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