USING GENETIC DIVERSITY OF IMPROVE QUANTITATIVE DISEASE RESISTANCE AND AGRONOMIC TRAITS OF CORN
Location: Plant Science Research
Title: Multivariate analysis of maize disease resistances suggests a pleiotropic genetic basis and implicates a glutathione S-transferase gene
Submitted to: Proceedings of the National Academy of Sciences
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: March 18, 2011
Publication Date: May 3, 2011
Citation: Wisser, R., Kolkman, J., Patzoldt, M., Holland, J.B., Jianming, Y., Krakowsky, M.D., Nelson, R., Balint Kurti, P.J. 2011. Multivariate analysis of maize disease resistances suggests a pleiotropic genetic basis and implicates a glutathione S-transferase gene. Proceedings of the National Academy of Sciences. 108:7339-7344.
Interpretive Summary: Plants in the field are usually are infected by many diseases at once. In most cases the genes that provide resistance confer resistance to just one specific disease amongst the many. In this paper we examine the possibility that there are genes that confer partial resistance to several diseases by examining an extremely diverse set of maize lines and looking for specific alleles that tend to be associated with resistance to multiple diseases. We show good evidence that such genes exist and identify 3 genes which are strongly statistically associated with multiple disease resistance.
Plants are attacked by pathogens representing diverse taxonomic groups, such that genes providing multiple disease resistance (MDR) would likely be under positive selection pressure. We examined the novel proposition that naturally occurring allelic variants may confer MDR. To do so, we applied a novel extension to structured association mapping, allowing for the analysis of correlated complex traits and the identification of pleiotropic genes. The analytical approach used here is directly applicable to any species and set of traits exhibiting correlation. From our analysis of a diverse panel of maize inbred lines, we discovered high positive genetic correlations between resistances to three globally important fungal diseases. The maize panel studied exhibits rapidly decaying linkage disequilibrium that generally occurs within one or two kilobases—less than the length of an average maize gene. The positive correlations therefore suggested that functional allelic variation at specific genes for MDR do exist in maize. Using a multivariate test statistic, we showed that sequence variation at a glutathione S-transferase gene was associated with resistance to each of the three diseases. Re-sequencing analysis pinpointed mutations in the coding domain defining glutathione S-transferase substrate specificity, providing biochemical plausibility for the association. The documented role of glutathione S-transferases in cytoprotection, including pathogen defense, also provided biological plausibility for the association. Glutathione S-transferases and other proteins involved in detoxification are likely to be an important component of quantitative variation in single and multiple disease resistance.