Paranoid Plants: When Too Much Genetic Diversity Is Harmful

My group is addressing fundamental questions in evolutionary biology, using both genome-first and phenotype-first approaches. A few years ago, we discovered that Arabidopsis thaliana is a great model for the study of hybrid necrosis. This widespread syndrome of hybrid failure in plants is caused by plant paranoia – regardless of the presence of enemies, plants “think” they are being attacked by pathogens. The consequence is autoimmunity, which can be extreme enough to kill plants before they set seeds. Over the past decade, we have studied in detail the underlying genetics, finding that often only one or two loci are involved, with most of them encoding NLR immune receptors. The NLR gene family is the most variable gene family in plants, and it is thus not surprising that they are often involved in genome-genome conflict, with alleles at one locus greatly changing the activity of alleles at another locus. Similarly, we have found that autoimmunity due to allelic variation at the ACD6 locus, which probably encodes a channel, is modulated by a slew of extragenic suppressors. I will describe what we have learned and how our unique angle on studying the plant immune system has led to insights that were not obtained with conventional laboratory genetics. Additional information about our work can be found on our website http://weigelworld.org