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Title: A genome wide association study reveals markers and genes associated with Fusarium kernel rot resistance in a maize diversity panel

Author
item STAGNATI, LORENZO - Catholic University Of The Sacred Heart Italy
item LANUBILE, ALESSANDRA - Catholic University Of The Sacred Heart Italy
item SAMAYOA, LUIS FERNANDO - North Carolina State University
item BRAGALANTI, MARIO - Catholic University Of The Sacred Heart Italy
item GIORNI, PAOLA - Catholic University Of The Sacred Heart Italy
item BUSCONI, MATTEO - Catholic University Of The Sacred Heart Italy
item Holland, Jim - Jim
item MAROCCO, ADRIANO - Catholic University Of The Sacred Heart Italy

Submitted to: Journal of Experimental Botany
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/19/2018
Publication Date: 2/7/2019
Citation: Stagnati, L., Lanubile, A., Samayoa, L., Bragalanti, M., Giorni, P., Busconi, M., Holland, J.B., Marocco, A. 2019. A genome wide association study reveals markers and genes associated with Fusarium kernel rot resistance in a maize diversity panel. Journal of Experimental Botany. 9:571-579.

Interpretive Summary: Fusarium ear rot is an important disease of corn worldwide, and particularly in the southeastern USA. Our research group has for many years studied the genetics of resistance to this disease as measured on mature ears of plants grown in the field. A distinct component of resistance to this disease is expressed in germinating seedlings. It is possible that systemic infections that begin in seeds may be suppressed in some genotypes, leading to better whole plant health. It was not known if there is variation for seedling resistance among corn genotypes or how that is related to adult plant ear rot resistance. In this experiment, germinating seedlings of more than 200 diverse corn inbred lines were evaluated for resistance to Fusarium infection. Significant variation for resistance was observed, and several genes associated with this type of resistance were identified. It may be possible to combine seedling resistance with adult plant resistance to maximize resistance to this disease.

Technical Abstract: Fusarium verticillioides infects maize, causing ear rot, yield loss and contamination by the mycotoxin fumonisin. In the present study, Genome Wide Association Study (GWAS) was applied to Fusarium kernel rot (FKR) resistance in a maize diversity panel using 226,446 SNP markers. Phenotypes were scored on artificially inoculated kernels using the rolled towel assay (RTA). GWAS resulted in 164 SNPs significantly associated with the traits examined. Four SNPs were associated with disease severity score after inoculation, 153 SNPs were associated with severity in asymptomatic kernels and 7 with the difference between the severity ratings in inoculated and non-inoculated seeds. A set of genes containing or physically closed to the significant SNPs were identified as candidates for FKR resistance. Functional analysis revealed that many of these genes are directly involved in plant defense against pathogens and stress responses; these include transcription factors, chitinase, cytochrome P450, and proteins implicated in ubiquitination. In addition 25 genes were found in high linkage disequilibrium with the associated SNPs identified by GWAS and four of them directly involved in disease resistance. These findings contribute to the understanding the complex system of maize-F. verticillioides interaction. SNPs identified can improve genomic selection for FKR resistance and markers associated with the severity in asymptomatic kernels may help to control the endophytic infection.