|Holland, Jim - Jim|
Submitted to: Phytopathology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/30/2006
Publication Date: 2/23/2007
Citation: Holland, J.B., Robertson-Hoyt, L., Betran, J., Payne, G., White, D., Isakeit, T., Maragos, C.M., Molnar, T. 2007. Relationships among resistances to Fusarium and Aspergillus ear rots and contamination by fumonisin and aflatoxin in maize. Phytopathology. 97(3):311-317. Interpretive Summary: US corn is susceptible to infection by Fusarium and Aspergillus fungi, both of which produce ear rot diseases, and both of which also produce mycotoxins, which are harmful to animal and human health. Fusarium fungi can produce the mycotoxin fumonisin, and Aspergillus fungi can produce the mycotoxin aflatoxin. Resistance to these diseases is genetically complex and the environment plays a major role in infection and mycotoxin production. Previously, there have been no studies on the potential for common resistances to the two diseases in corn. To investigate this, we selected 25 corn lines that previous studies had shown were highly resistant to contamination by fumonisin and 25 lines that were susceptible to contamination by fumonisin. The lines were grown in replicated studies across two years in both Texas and North Carolina, and each line was inoculated with both fungi. We found that the lines that were resistant to fumonisin contamination were also more resistant to aflatoxin contamination. This result suggests that there are common mechanisms of host plant resistance to the accumulation of the two mycotoxins produced by different fungi.
Technical Abstract: Fusarium verticillioides, F. proliferatum, and Aspergillus flavus cause ear rots of maize and contaminate the grain with mycotoxins (fumonisin or aflatoxin). The objective of this study was to investigate the relationships between resistance to Fusarium and Aspergillus ear rots and fumonisin and aflatoxin contamination. Based on a previous study of 143 recombinant inbred lines from the cross NC300 × B104, the 24 lines with highest and 24 lines with lowest mean fumonisin concentration were selected for further evaluation. Paired plots of each line were inoculated with F. verticillioides and F. proliferatum or with A. flavus in replicated trials in four environments. The low fumonisin group had significantly lower levels of fumonisin, aflatoxin, and Fusarium and Aspergillus ear rots. Across environments, all four traits were significantly correlated, ranging from rG = 0.88 (aflatoxin and Aspergillus ear rot) to rG = 0.99 (Fusarium and Aspergillus ear rots). QTLs were identified and their effects estimated. One QTL affected both toxin concentrations, one QTL affected both ear rots, and one QTL affected Aspergillus and Fusarium rots and fumonisin. These results suggest that at least some of the genes involved in resistance to ear rots and mycotoxin contamination are identical or genetically linked.