A herbicide-resistant ACCase 1781 Setaria mutant shows higher fitness than wild type

It is often alleged that mutations conferring herbicide resistance have a negative impact on plant fitness. A mutant ACCase1781 allele endowing resistance to the sethoxydim herbicide was introgressed from a resistant green foxtail (Setaria viridis (L.) Beauv) population into foxtail millet (S. itali...

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Bibliographic Details
Published in:Heredity 2010-10, Vol.105 (4), p.394-400
Main Authors: Wang, T, Picard, J C, Tian, X, Darmency, H
Format: Article
Language:English
Subjects:
Acetyl-CoA Carboxylase - genetics
Chimera - genetics
Chimera - growth & development
Gene Frequency
Genetic Fitness - genetics
Genetic Fitness - physiology
Genotype
Germination - genetics
Germination - physiology
Herbicide Resistance - genetics
Herbicides
Human health and pathology
Life Sciences
Models, Genetic
Mutant Proteins - genetics
Mutation
Poaceae - genetics
Poaceae - physiology
Polymorphism, Single Nucleotide - physiology
Resistance to control
Seedlings - genetics
Seedlings - growth & development
Setaria
Setaria Plant - enzymology
Setaria Plant - genetics
Setaria Plant - growth & development
Setaria viridis
Wilderness areas
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Summary:It is often alleged that mutations conferring herbicide resistance have a negative impact on plant fitness. A mutant ACCase1781 allele endowing resistance to the sethoxydim herbicide was introgressed from a resistant green foxtail (Setaria viridis (L.) Beauv) population into foxtail millet (S. italica (L.) Beauv.). (1) Better and earlier growth of resistant plants was observed in a greenhouse cabinet. (2) Resistant plants of the advanced BC7 backcross generation showed more vigorous juvenile growth in the field, earlier flowering, more tillers and higher numbers of grains than susceptible plants did, especially when both genotypes were grown in mixture, but their seeds were lighter than susceptible seeds. (3) Field populations originating from segregating hybrids had the expected allele frequencies under normal growth conditions, but showed a genotype shift toward an excess of homozygous resistant plants within 3 years in stressful conditions. Lower seed size, lower germination rate and perhaps unexplored differences in seed longevity and predation could explain how the resistant plants have the same field fitness over the whole life cycle as the susceptible ones although they produce more seeds. More rapid growth kinetics probably accounted for higher fitness of the resistant plants in adverse conditions. The likelihood of a linkage with a beneficial gene is discussed versus the hypothesis of a pleiotropic effect of the ACCase resistance allele. It is suggested that autogamous species like Setaria could not develop a resistant population without the help of a linkage with a gene producing a higher fitness.
ISSN:0018-067X
1365-2540
0018-067X
DOI:10.1038/hdy.2009.183