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ARS Home » Southeast Area » Mississippi State, Mississippi » Crop Science Research Laboratory » Corn Host Plant Resistance Research » Research » Publications at this Location » Publication #305397

Title: Characterization of the chitinase gene family and the effect on A. flavus and aflatoxin resistance in maize.

item Hawkins, Leigh
item Mylroie, John
item OLIVEIRA, DAFNE - Universidade Federal De Mato Grosso
item Smith, Jesse
item OZKAN, SEVAL - Mississippi State University
item Windham, Gary
item Williams, William
item Warburton, Marilyn

Submitted to: PLOS ONE
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/30/2014
Publication Date: 6/19/2015
Citation: Hawkins, L.K., Mylroie, J.E., Oliveira, D., Smith, J.S., Ozkan, S., Windham, G.L., Williams, W.P., Warburton, M.L. 2015. Characterization of the chitinase genes and their effect on A. flavus and aflatoxin accumulation resistance. PLoS One 10(6):e0126185. doi:10/1371/journal.pone.0126185.

Interpretive Summary: Corn is a valuable commodity, which is used as a feed grain and food staple around the world. It is susceptible to production of a toxin produced by the fungi in the genus Aspergillus. This aflatoxin is a potential carcinogen. The goal of researchers worldwide is to develop corn lines that are resistant to infection by the fungus and/or production of the toxin. Chitinase enzymes from corn have been shown to increase insect and fungal resistance. Evaluating naturally occurring chitinase genes, we have found variants which may contribute significantly to increased resistance of the corn to infection or to accumulation of the toxin. These variants (or markers) are presented to aid in improving this trait. Further studies are underway to validate these results in different genetic backgrounds.

Technical Abstract: Maize (Zea mays L.) is a crop of global importance, but is prone to contamination by aflatoxins produced by fungi in the genus Aspergillus. The development of resistant germplasm and the identification of genes contributing to resistance would aid in the reduction of the problem with a minimal need for intervention by farmers. Chitinolytic enzymes respond to attack by potential pathogens and have been demonstrated to increase insect and fungal resistance in plants. Here, all chitinase genes in the maize genome were characterized via sequence diversity and expression patterns. Recent evolution within this gene family was noted. Markers from within each gene were developed, and used to map the phenotypic effect on resistance of each gene in up to four QTL mapping populations and one association panel. Seven chitinase genes were identified that had alleles associated with increased resistance to aflatoxin accumulation and A. flavus infection in field grown maize. The chitinase in bin 1.05 identified a new and highly significant QTL, while chitinase genes in bins 2.04 and 5.03 fell directly beneath the peak of previously published QTL. The expression patterns of these genes corroborate possible grain resistance mechanisms. Markers from within the gene sequences or very closely linked to them are presented to aid in the use of Marker Assisted Selection to improve this trait. Validation of these genes in independent tests and genetic backgrounds are now underway.