Chemical Communication in a Post-Genomic World (2003) / Chapter Skim
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15 Evolutionary dynamics of an Arabidopsis insect resistance quantitative trait locus
15 Evolutionary dynamics of an Arabidopsis insect resistance quantitative trait locus
Pages 75-80
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From page 75... ...
Molecular genetics allows us to clone and characterize genes controlling secondary metabolism and insect resistance. When these genes are identified, molecular population genetics provides statistical tests for neutral evolution or natural selection, thus elucidating the evolutionary forces responsible for genetic variation in ecologically important traits.
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From page 76... ...
An additional layer of complexity is added by apparent interlocus gene conversion between MAM1 and MAM2. Pairwise comparisons of sequence similarity between MAM genes of ecotypes containing both a MAM2 and a MAM1 locus reveal a maximal divergence between the Sorbo MAM2 and MAM1 genes; both nucleotide and protein sequences differ by ~5.0% (Table 1~.
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From page 77... ...
A total of 5,000 F2 progeny were screened for recombination in a 210-kb interval containing the GS-Elong region. Prereproductive rosette plants from 58 recombinant, homozygous, near-isogenic F4 lines were assayed for glucosinolates, growth rate, and resistance to larvae of two herbivorous lepidopteran insects, P xylostella and S
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From page 78... ...
for growth rate (GR) , total aliphatic glucosinolates (GS)
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From page 79... ...
. Natural genetic variation at MAM2 shows too much intermediate-frequency nucleotide polymorphism and too many amino acid variants, relative to neutral predictions, suggesting that balancing selection maintains functional diversity at this ecologically important gene.
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From page 80... ...
Further more, prereproductive vegetative growth rate measures resource availability in the exact environment and growth stage where the Ler-0 MAM2 allele causes increased aliphatic glucosinolate concentration and greater resistance to the generalist herbivore, and allows us to test for allocation costs independently of tolerance (1~. However, highly replicated quantification of ju venile growth rate in the fine-scale mapping lines gave no evidence for the existence of allocation costs.
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