Detecting genes that influence biofortification traits in cereal grain could help increase the concentrations of bioavailable mineral elements in crops to solve the global mineral malnutrition problem. The aims of this study were to detect the quantitative trait loci (QTLs) for phosphorus (P), iron (Fe), zinc (Zn), and magnesium (Mg) concentrations in maize grain in a mapping population, as well as QTLs for bioavailable Fe, Zn, and Mg, by precalculating their respective ratios with P. Elemental analysis of grain samples was done by coupled plasma-optical emission spectrometry in 294 F(4) lines of a biparental population taken from field trials of over 3 years. The population was mapped using sets of 121 polymorphic markers. QTL analysis revealed 32 significant QTLs detected for 7 traits, of which some were colocalized. The Additive-dominant model revealed highly significant additive effects, suggesting that biofortification traits in maize are generally controlled by numerous small-effect QTLs. Three QTLs for Fe/P, Zn/P, and Mg/P were colocalized on chromosome 3, coinciding with simple sequence repeats marker bnlg1456, which resides in close proximity to previously identified phytase genes (ZM phys1 and phys2). Thus, we recommend the ratios as bioavailability traits in biofortification research.

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1 This review presents the latest research regarding maize resistance breeding against western corn rootworm (WCR) in the U.S.A. and Europe. 2 Investigations in Europe on the development of maize cultivars possessing resistant mechanisms against WCR are just beginning. In 2003, the European Commission implemented measures aimed at slowing down the spread of the WCR in Europe.Nevertheless, this pest has already been found in 20 countries of the European region. To establish a sustainable production system, the evaluation of native (nontransgenic) resistance in maize cultivars is essential. 3 This review emphasizes the future challenges involved in the research of native resistance breeding in maize against the insect.

Abstract:The resistance of 35 inbred lines and their 70 hybrids with two testers to stalk rot is described and the results of natural and artificial stalk infection are compared. A mixture of Fusarium spp. spores was used for artificial infections. The disease was scored for two years. Inbreds and hybrids differed significantly in resistance and infection types in both years. Generally, disease scores of hybrids were lower than of inbreds. No close association was found between lines and their testcross hybrids (r = -0.06 to 0.29) and between hybrids with the two testers (r = -0.04 to 0.38). The correlation coefficients of disease scores after natural and artificial infection were in inbreds and in hybrids highly significant (r = 0.45-0.87). The results suggest, that Fusarium stalk rot resistance should be tested in both inbreds and hybrids. We recommend for maize breeding, that tests with artificial infection should be followed by tests under natural infection.