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Title: Responses to recurrent index selection for reduced fusarium ear rot and lodging and for increased yield in maize

Author
item HORNE, DAVID - North Carolina State University
item ELLER, MAGEN - North Carolina State University
item Holland, Jim - Jim

Submitted to: Crop Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/27/2015
Publication Date: 12/30/2015
Citation: Horne, D., Eller, M., Holland, J.B. 2015. Responses to recurrent index selection for reduced fusarium ear rot and lodging and for increased yield in maize. Crop Science. 56:85-94.

Interpretive Summary: Fusarium ear rot disease of corn is common worldwide and can reduce yield. The causal fungus also can contaminate corn grain with a mycotoxin hazardous to human and animal health. The disease cannot be controlled with fungicide, so breeding for resistance is needed. We created a corn population by intermating diverse inbred lines and selected against Fusarium ear rot for three generations. We found that selection significantly reduced susceptibility to both Fusarium ear rot and also to contamination by fumonisin. Our results are the first demonstration of the indirect effect of selection against Fusarium ear rot on reduction of fumonisin contamination. This suggests that corn breeders can effectively reduce susceptibility to fumonisin contamination by evaluating ear rot and selecting against, which is much easier and faster than conducting chemical evaluations of corn grain to detect fumonisin.

Technical Abstract: Fusarium ear rot caused by the pathogen Fusarium verticillioides (Sacc.) Nirenberg damages maize (Zea mays L.) grain production and is associated with contamination of grain by fumonisin, a mycotoxin harmful to both humans and animals. Recurrent selection may be an effective way to combine improvements in resistance to Fusarium ear rot with improved grain yield and lodging resistance. To test this hypothesis, three cycles of recurrent index selection based on evaluating S0:1 lines for Fusarium ear rot, grain yield, and lodging were implemented in a genetically broad-based population. Direct intra-population response to selection in the target traits was measured by comparing lines sampled from Cycle 0 and Cycle 3 populations. In addition, indirect response for fumonisin contamination was also measured along with indirect response for agronomic traits when crossed to commercial inbred tester, FR1064. Results indicate significant direct gain from selection for Fusarium ear rot, but no significant gains for yield or lodging resistance. Indirect gains were also observed for Fusarium ear rot resistance in topcrosses to an unrelated tester line and for fumonisin contamination both within the selection population and in topcrosses. Our results are the first demonstration of the indirect effect of selection against Fusarium ear rot on reduction of fumonisin contamination. Heritabilities for target traits did not decrease over generations, indicating potential for further genetic gain from selection in this population.