Quantitative trait loci mapping for Gibberella ear rot resistance and associated agronomic traits using genotyping-by-sequencing in maize
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Unique and co-localized chromosomal regions affecting Gibberella ear rot disease resistance and correlated agronomic traits were identified in maize.
Dissecting the mechanisms underlying resistance to Gibberella ear rot (GER) disease in maize provides insight towards more informed breeding. To this goal, we evaluated 410 recombinant inbred lines (RIL) for GER resistance over three testing years using silk channel and kernel inoculation techniques. RILs were also evaluated for agronomic traits like days to silking, husk cover, and kernel drydown rate. The RILs showed significant genotypic differences for all traits with above average to high heritability estimates. Significant (P < 0.01) but weak genotypic correlations were observed between disease severity and agronomic traits, indicating the involvement of agronomic traits in disease resistance. Common QTLs were detected for GER resistance and kernel drydown rate, suggesting the existence of pleiotropic genes that could be exploited to improve both traits at the same time. The QTLs identified for silk and kernel resistance shared some common regions on chromosomes 1, 2, and 8 and also had some regions specific to each tissue on chromosomes 9 and 10. Thus, effective GER resistance breeding could be achieved by considering screening methods that allow exploitation of tissue-specific disease resistance mechanisms and include kernel drydown rate either in an index or as indirect selection criterion.
KeywordsQuantitative Trait Locus Agronomic Trait Quantitative Trait Locus Region Recombinant Inbred Line Population Inoculation Technique
This project was funded by the Agriculture and Agri-Food Canada (AAFC) and the Canadian Field Crop Research Alliance. We acknowledge the genotyping-by-sequencing service obtained from Ed Buckler’s group at Cornell University. We also thank Danielle Schneiderman, Anne Johnston, Whynn Bosnich, Phillipe Couroux, Wubshet Bekele, Harman Komal, Suzette Janse Vans Rensburg, Emily-Ann Butler, Fatoumata Bah, Constantin Voloaca, and Jinhe Wu for the technical support. We appreciate comments and suggestions of anonymous reviewers for improving the manuscript.
Compliance with ethical standards
The research was conducted in compliance with the current laws of Canada.
Conflict of interest
The authors declare that they have no conflict of interest.
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