Plant defense against pathogens is induced by R-genes, a large multigene family of signal transducing proteins. Approximately a dozen R-genes have been shown to be segregating for both resistance and susceptibility alleles, and several of these are known to harbor ancient polymorphisms. R-genes can also show evidence of rapid, adaptive evolution, presumably as a consequence of coevolutionary interactions with pathogens. That both of these evolutionary processes -balancing selection and adaptive evolution -occur in the same gene is remarkable, and requires explanation. The general aims of this proposal are to elucidate the mechanisms of natural selection acting on segregating R-gene alleles and to determine the physiological basis for their fitness differences. We believe that both these pursuits are necessary to fully understand the evolutionary genetics of disease resistance variation. Sequence variation at three complex loci containing a variable number of R-gene repeats will also be investigated. We hypothesize that complex loci evolve in response to strong balancing selection and large costs of specific resistance alleles. The data will allow us to evaluate alternative hypotheses, and potentially to unite simple and complex R-gene loci under a single model of selection.
Our specific aims i n this grant period will be to (1) Test the hypothesis that a large cost of resistance is characteristic of long-lived polymorphisms between resistance and null susceptibility alleles; (2) Test the prediction that this cost is lower for alleles that participate in a stable polymorphism between functional alternatives; (3) Analyze the cost of Rpml resistance by characterizing R and S lines in terms of gene expression, biochemical intermediates and biochemical end products; (4) Test the role of particular defense responses in generating the cost of Rpml resistance; (5) Characterize and contrast nucleotide polymorphism of single-copy R-gene loci in a reference set of 96 A. thaliana accessions, and of tandem arrays in a subset of these samples, to identify the spectrum of evolved responses by R-genes to disease; and (6) Develop population genetic models of the major modes of R-gene polymorphism.

Agency
National Institute of Health (NIH)
Institute
National Institute of General Medical Sciences (NIGMS)
Type
Research Project (R01)
Project #
5R01GM057994-06
Application #
6901076
Study Section
Genetics Study Section (GEN)
Program Officer
Eckstrand, Irene A
Project Start
1998-07-01
Project End
2008-06-30
Budget Start
2005-07-01
Budget End
2006-06-30
Support Year
6
Fiscal Year
2005
Total Cost
$327,303
Indirect Cost
Name
University of Chicago
Department
Biology
Type
Schools of Medicine
DUNS #
005421136
City
Chicago
State
IL
Country
United States
Zip Code
60637
MacQueen, Alice; Sun, Xiaoqin; Bergelson, Joy (2016) Genetic architecture and pleiotropy shape costs of Rps2-mediated resistance in Arabidopsis thaliana. Nat Plants 2:16110
Zhang, Xiaohui; Yang, Sihai; Wang, Jiao et al. (2015) A genome-wide survey reveals abundant rice blast R genes in resistant cultivars. Plant J 84:20-28
Karasov, Talia L; Kniskern, Joel M; Gao, Liping et al. (2014) The long-term maintenance of a resistance polymorphism through diffuse interactions. Nature 512:436-440
Horton, Matthew W; Bodenhausen, Natacha; Beilsmith, Kathleen et al. (2014) Genome-wide association study of Arabidopsis thaliana leaf microbial community. Nat Commun 5:5320
Bodenhausen, Natacha; Horton, Matthew W; Bergelson, Joy (2013) Bacterial communities associated with the leaves and the roots of Arabidopsis thaliana. PLoS One 8:e56329
Horton, Matthew W; Hancock, Angela M; Huang, Yu S et al. (2012) Genome-wide patterns of genetic variation in worldwide Arabidopsis thaliana accessions from the RegMap panel. Nat Genet 44:212-6
Huang, Yu S; Horton, Matthew; Vilhjálmsson, Bjarni J et al. (2011) Analysis and visualization of Arabidopsis thaliana GWAS using web 2.0 technologies. Database (Oxford) 2011:bar014
Kniskern, Joel M; Barrett, Luke G; Bergelson, Joy (2011) Maladaptation in wild populations of the generalist plant pathogen Pseudomonas syringae. Evolution 65:818-30
Hu, Tina T; Pattyn, Pedro; Bakker, Erica G et al. (2011) The Arabidopsis lyrata genome sequence and the basis of rapid genome size change. Nat Genet 43:476-81
Atwell, Susanna; Huang, Yu S; Vilhjálmsson, Bjarni J et al. (2010) Genome-wide association study of 107 phenotypes in Arabidopsis thaliana inbred lines. Nature 465:627-31

Showing the most recent 10 out of 15 publications