ASPB President's Symposium
Bomblies, Kirsten , Weigel, Detlef .
When good genes behave badly - hybrid incompatibility in Arabidopsis thaliana.
Epistasis – the non-additive interaction among gene products - is a key ingredient in evolution. It has been implicated in disparate processes including morphological evolution, hybrid vigor, genetic incompatibility and speciation. We investigated the nature and prevalence of deleterious epistasis within a model species, Arabidopsis thaliana, by performing a survey of over 900 F1 hybrids among 293 A. thaliana strains. While most hybrids were phenotypically normal and fully fertile, about 2% were severely compromised. These all showed phenotypes characteristic of a syndrome commonly called “hybrid necrosis,” a type of hybrid failure that has been reported in crosses within and between species in many plant taxa. We show that A. thaliana necrosis cases involve autoimmune-like responses triggered by relatively simple epistatic interactions. In one case, we identified an allele of an NB-LRR disease resistance (R) gene homolog carried by one parent that is both necessary and sufficient for hybrid necrosis when combined with a specific allele at a second locus originating from the other parent. This system provides a molecular model for hybrid necrosis. Our results implicate rapidly evolving pathogen response genes, and by extension, evolutionary pressures related to host-pathogen conflict, in a recurrent genetic incompatibility syndrome that may play a role in plant speciation.
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1 - Max Planck Institute for Developmental Biology, Molecular Biology, Spemannstrasse 37-39, Tuebingen, 72076, Germany
2 - Max Planck Institute for Developmental Biology, Molecular Biology
Presentation Type: ASPB Major Symposium
Location: International Ballroom North/Hilton
Date: Wednesday, July 11th, 2007
Time: 2:00 PM