Relationships of resistance to Fusarium ear rot and fumonisin contamination with agronomic performance of maize

Resistance to Fusarium ear rot [caused by Fusarium verticillioides (Sacc.) Nirenberg (synonym F. moniliforme Sheldon) (teleomorph: Gibberella moniliformis) and F. proliferatum (Matsushima) Nirenberg (teleomorph: G. intermedia)] and fumonisin contamination is heritable and controlled by at least 11 gene regions in a maize (Zea mays L.) population created by backcrossing the highly resistant donor line, GE440, to the susceptible but commercially successful recurrent parent line, FR1064. The relationship between resistances to Fusarium ear rot and fumonisin contamination and agronomic performance has not been reported. Therefore, the objective of this study was to examine the relationship between disease resistance and agronomic utility in this population by measuring resistances to Fusarium ear rot and fumonisin contamination in BC1F1:2 lines, and yield and agronomic performance in topcrosses of these lines. Fumonisin contami-1, nation was not correlated with yield, but two fumonisin quantitative trait loci (QTL) mapped to similar positions as yield QTL. Fusarium ear rot had a small positive correlation with topcross yield (r = 0.29), but QTL for the two traits mapped to distinct genomic positions. Similar results for other traits indicate that QTL can contribute in opposite directions to the overall genetic correlations between traits and that some trait correlations arise in the absence of detectable QTL effects on both traits. In general, no strong relationships were observed between disease resistance traits and agronomic traits, thus selection for increased resistance should not unduly affect agronomic performance.