Submitted to: Mycopathologia
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/3/2005
Publication Date: 2/28/2006
Citation: Wilson, J.P., Jurjevic, Z., Hanna, W.W., Wilson, D.M., Potter, T.L., Coy, A.E. 2006. Host-specific variation in infection by toxigenic fungi and contamination by mycotoxins in pearl millet and corn. Mycopathologia. 161:101-107. Interpretive Summary: Pearl millet is widely consumed by people in semi-arid regions in both Africa and Asia, and it has several characteristics that make it attractive as a crop for the southern U.S. It is productive in acidic, relatively infertile, and drought-prone soils and requires no irrigation. The grain is a proven high-quality addition to poultry rations. In the southern U.S., dryland corn is prone to high concentrations of aflatoxins and fumonisins in drought years. Concentrations of aflatoxins and fumonisins in pearl millet have been low or not detectable to date. Adjacent cultivation of corn and pearl millet and overlapping periods of grain maturation demonstrated differences in susceptibility to pre-harvest grain molds and mycotoxins between the host crops. Low levels of infection by A. flavus and F. verticillioides and low concentrations of their associated mycotoxins were observed in pearl millet compared to corn. The low concentrations of pre-harvest aflatoxin and fumonisins observed in pearl millet are likely to be directly attributable to host-specific differences in incidence of pre-harvest fungal infection. Inherently lower levels of carcinogenic mycotoxins increases the value of pearl millet in feed and as food for people in drought-prone regions.
Technical Abstract: Pearl millet is widely consumed in regions of Africa and Asia, and is increasingly being grown as an alternative grain in the drought-prone, acidic, and relatively infertile soils of the southern Coastal Plain region of the southeastern United States. Pearl millet and corn were grown in dryland conditions and grains were compared for preharvest infection by potentially toxigenic fungi and contamination by mycotoxins. Corn hybrids Agripro 9909 and Pioneer 3146, and pearl millet Tifgrain 102 were grown in 2000 and 2001; pearl millet HGM 100 was included in the test in 2001. Hybrids were sown on multiple planting dates in each year to induce variation in flowering time. Host species differed in the frequency of isolation of potentially toxigenic fungal species in both years. Across years, corn hybrids were more prone to infection by Aspergillus flavus Link (maximum isolation frequency = 8.8%) and Fusarium verticillioides (Sacc.) Nirenberg (maximum isolation frequency = 72.8%), with corresponding greater concentrations of aflatoxins (maximum concentration = 204.9 'g kg-1) and fumonisins (maximum concentration = 34.0 mg kg-1). Pearl millet was more prone to infection by F. semitectum Berk. & Ravenel (maximum isolation = 74.2%) and F. chlamydosporum Wollenweb & Reinking (maximum isolation = 33.0%), and contamination by moniliformin (maximum contamination = 92.1 'g kg-1). Beauvericin (maximum concentration = 414.6 'g kg-1) was present in both hosts . Planting date of corn affected aflatoxin and beauvericin contamination in 2000, and fumonisin concentration in 2001. The observed differences in mycotoxin contamination of the grains, which are likely due to host-specific differences in susceptibility to pre-harvest mycoflora, can affect food safety when the crops are grown under stress conditions.