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Title: Diallel analysis of resistance to fusarium ear rot and fumonisin contamination in maize

Author
item HUNG, H - North Carolina State University
item Holland, Jim - Jim

Submitted to: Crop Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/7/2012
Publication Date: 8/20/2012
Citation: Hung, H.Y., Holland, J.B. 2012. Diallel analysis of resistance to fusarium ear rot and fumonisin contamination in maize. Crop Science. 52:2173-2181.

Interpretive Summary: The fungus Fusarium verticillioides infects maize ears and kernels, resulting in Fusarium ear rot disease, reduced grain yields, and contamination of grain with the mycotoxin fumonisin. In previous research, we showed that selection for resistance to this disease was effective in maize inbreds. However, it was unknown how effective selection in inbred generations would be for improving resistance to the disease in hybrids corn. The objectives of this study were to study the relationship between resistance measured in inbred and hybrid generations. We crossed 18 inbred lines in all possible combinations and tested the18 inbreds and 153 hybrids in field trials. Hybrids had on average 27% less ear rot and 30% less fumonisin content than their inbred parents, demonstrating the importance of hybrid vigor to disease resistance. Resistance in inbreds was strongly correlated with resistance in hybrids. Genetic variation for resistance was much greater in inbred lines than among, hybrids. These results suggest that the most efficient way to improve Fusarium ear rot and fumonisin contamination resistances in hybrids is to evaluate and select among inbred lines before using resources to create and evaluate hybrids.

Technical Abstract: The fungus Fusarium verticillioides infects maize ears and kernels, resulting in Fusarium ear rot disease, reduced grain yields, and contamination of grain with the mycotoxin fumonisin. Typical hybrid maize breeding programs involve selection for both favorable inbred and hybrid performance, and the relative emphasis placed on inbred versus hybrid selection depends on heritability of and the genetic correlation between resistance in the different inbreeding generations. The objectives of this study were to assess the importance of general combing ability (GCA) and specific combining ability (SCA) for resistance to Fusarium ear rot and fumonisin contamination, to estimate the correlation between resistance measured in inbred and hybrid generations, and to study the relationship between resistance and vigor (measured by grain yield). We evaluated a diallel mating of 18 inbred lines selected from different heterotic groups and varying for levels of resistance. Hybrids had on average 27% less ear rot and 30% less fumonisin content than their inbred parents, demonstrating the importance of hybrid vigor to disease resistance. Both GCA and SCA were significant for yield and disease resistance, and inbred performance per se and corresponding GCA in hybrids were significantly correlated (r is greater than or equal to 0.78). Genetic variation for resistance is much greater in inbred lines than among, hybrids, however. These results suggest that the most efficient way to improve Fusarium ear rot and fumonisin contamination resistances in hybrids is to evaluate and select among inbred lines before using resources to create and evaluate hybrids.