Journal Article

Evolution of disease response genes in loblolly pine: insights from candidate genes

González-Martínez, Santiago C., Neale, David B., Wright, Mark H., Ersoz, Elhan S., Langley, Charles H.

2010

Overview

Background: Host-pathogen interactions that may lead to a competitive co-evolution of virulence and resistance mechanisms present an attractive system to study molecular evolution because strong, recent (or even current) selective pressure is expected at many genomic loci. However, it is unclear whether these selective forces would act to preserve existing diversity, promote novel diversity, or reduce linked neutral diversity during rapid fixation of advantageous alleles. In plants, the lack of adaptive immunity places a larger burden on genetic diversity to ensure survival of plant populations. This burden is even greater if the generation time of the plant is much longer than the generation time of the pathogen. Methodology/Principal Findings: Here, we present nucleotide polymorphism and substitution data for 41 candidate genes from the long-lived forest tree loblolly pine, selected primarily for their prospective influences on host-pathogen interactions. This dataset is analyzed together with 15 drought-tolerance and 13 wood-quality genes from previous studies. A wide range of neutrality tests were performed and tested against expectations from realistic demographic models. Conclusions/Significance: Collectively, our analyses found that axr (auxin response factor), caf1 (chromatin assembly factor) and gatabp1 (gata binding protein 1) candidate genes carry patterns consistent with directional selection and erd3 (early response to drought 3) displays patterns suggestive of a selective sweep, both of which are consistent with the arm-race model of disease response evolution. Furthermore, we have identified patterns consistent with diversifying selection at erf1-like (ethylene responsive factor 1), ccoaoemt (caffeoyl-CoA-O-methyltransferase), cyp450-like (cytochrome p450-like) and pr4.3 (pathogen response 4.3), expected under the trench-warfare evolution model. Finally, a drought-tolerance candidate related to the plant cell wall, lp5, displayed patterns consistent with balancing selection. In conclusion, both arms-race and trench-warfare models seem compatible with patterns of polymorphism found in different disease-response candidate genes, indicating a mixed strategy of disease tolerance evolution for loblolly pine, a major tree crop in southeastern United States.

• Publisher: CCSD,Public Library of Science,Public Library of Science (PLoS)
• Subject: Adaptive immunity / alleles / Analysis / Arabidopsis / Auxins / binding proteins / Biodiversity / Biological evolution / Cell walls / Cellulose - metabolism / Chromatin / Chromatin remodeling / Coevolution / Cytochrome / Cytochrome P450 / Cytochromes P450 / data collection / Demographics / disease models / disease resistance / Disease tolerance / DNA, Plant - genetics / Drosophila / Drought / Drought resistance / drought tolerance / Droughts / ethylene / Evergreen trees / Evolution / Evolution, Molecular / Evolutionary biology / Evolutionary Biology/Evolutionary and Comparative Genetics / Evolutionary Biology/Plant Genomes and Evolution / Evolutionary genetics / forest trees / Gene polymorphism / Genes / Genes, Plant / Genetic diversity / Genetic polymorphisms / Genetic Variation / Genetics / Genetics and Genomics/Plant Genomes and Evolution / Genetics and Genomics/Population Genetics / Genomes / Host-pathogen interactions / host-pathogen relationships / Hypotheses / Immunity / Insects / Life Sciences / Likelihood Functions / loci / Methyltransferase / Microbial drug resistance / Models, Genetic / Molecular evolution / Multiculturalism & pluralism / Mutation / Nucleotides / Pathogens / Pinaceae / Pine / Pine trees / Pinus sylvestris / Pinus taeda / Pinus taeda - genetics / Plant Biology/Plant-Biotic Interactions / Plant Diseases - genetics / Plant diversity / Plant populations / Plant sciences / Polymerase Chain Reaction - methods / Polymorphism / Polymorphism, Single Nucleotide / Population / Protein binding / Quantitative Trait Loci / resistance mechanisms / Southeastern United States / Statistical analysis / Studies / Tree crops / Trees / Virulence / Virulence (Microbiology) / Warfare / Wood / wood quality / Zea mays
• ISBN: 0002849953000