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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 #324439
Title: Quantitative trait loci (QTL) for reducing Aspergillus flavus infection and aflatoxin accumulation in corn

Author
item DHAKAL, RAMESH - LSU Agcenter
item Windham, Gary
item Williams, William
item SUBUDHI, PRASANTA - LSU Agcenter

Submitted to: Frontiers in Crops Science and Horticulture
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/3/2016
Publication Date: 12/20/2016
Citation: Dhakal, R., Windham, G.L., Williams, W.P., Subudhi, P.K. 2016. Quantitative trait loci (QTL) for reducing Aspergillus flavus infection and aflatoxin accumulation in corn. Molecular Breeding. 36:164. doi:10.1007/s11032-016-0590-8.

Interpretive Summary: Aflatoxin is a cancer causing compound produced by the fungi Aspergillus flavus and A. parasiticus, and is a major problem for corn producers in the southern United States. The development of corn lines with resistance to aflatoxin accumulation in grain is a effective way to solve the problem. Identification of quantitative trait loci (QTL) for reducing aflatoxin can accelerate development of aflatoxin resistant corn hybrids using marker-assisted selection. A mapping population developed from a cross involving a resistant inbred Mp715 and a susceptible inbred B73, was evaluated in field trials for two years to identify QTL for reduced aflatoxin accumulation in ears that had been artificially infected with A. flavus. Four to eight QTL associated with the level of aflatoxin contamination in grain were identified in both years. Additional QTL were detected for husk coverage which can have an effect on the amount of insect damage on developing ears and subsequent aflatoxin contamination. The susceptible corn line B73 and the resistant corn line Mp715 both contributed toward resistance. The husk cover and aflatoxin were significantly correlated in both years and this observation was further supported by overlapping of QTL in three genomic regions on chromosomes 4, 8 and 10. Since most of the QTL were of low to moderate effects, pyramiding of these QTL may lead to enhanced resistance to aflatoxin accumulation in corn.

Technical Abstract: Aflatoxin produced by Aspergillus flavus in corn poses significant health risks for both humans and livestock. Corn growers suffer huge economic losses due to increased aflatoxin accumulation in grain especially under drought and higher temperature stress conditions. Exploitation of host plant resistance in breeding program is a sustainable way to minimize aflatoxin contamination. Identification of quantitative trait loci (QTL) for reducing aflatoxin can accelerate development of aflatoxin resistant corn using marker-assisted selection. An F2:3 mapping population developed from a cross involving a resistant inbred Mp715 and a susceptible inbred B73, was evaluated in replicated field trials with artificial inoculation of A. flavus for two years to identify QTL for reduced aflatoxin accumulation. Using composite interval mapping, 4 to 8 QTL for aflatoxin content were identified in both years with contribution of individual QTL ranging from < 1 to 10% of phenotypic variation. More QTL were detected for husk cover with phenotypic variance range of <1 to 16% explained by individual QTL. Both B73 and Mp715 alleles at these QTL loci contributed toward resistance. The husk cover and aflatoxin were significantly correlated in both years and this observation was further supported by overlapping of QTL in three genomic regions on chromosomes 4, 8 and 10, where aflatoxin resistance QTLs were reported in previous studies. Since most of the QTL were of low to moderate effects, pyramiding of these QTL may lead to enhanced resistance to aflatoxin accumulation in corn.