Fusarium verticillioides (Sacc.) Nirenberg (synonym F. moniliforme Sheldon) (teleomorph: Gibberella moniliformis) and F. proliferatum (Matsushima) Nirenberg (teleomorph: G. intermedia) are fungal pathogens of maize (Zea mays L.) that cause ear rot and contaminate grain with fumonisins, a family of mycotoxins that adversely affect animal and human health. The objective of this study was to estimate heritabilities of and genotypic and phenotypic correlations between fumonisin concentration, ear rot, and flowering time in two maize populations. In the (GE440 3 FR1064) 3 FR1064 backcross population, the genotypic and phenotypic correlations between ear rot and fumonisin concentration were 0.96 and 0.40, respectively. Heritability estimated on an entry mean basis was 0.75 for fumonisin concentration and 0.47 for ear rot resistance. In the NC300 3 B104 recombinant inbred line population, the genotypic and phenotypic correlations between ear rot and fumonisin concentration were 0.87 and 0.64, respectively. Heritability estimated on an entry mean basis was 0.86 for fumonisin concentration and 0.80 for ear rot resistance. Correlations between fumonisin concentration and silking date were not significant in either population, and correlations between ear rot resistance and silking date were small (less than 0.30) in both populations. Moderate to high heritabilities and strong genetic correlations between ear rot and fumonisin concentration suggest that selection for reduced ear rot should frequently identify lines with reduced fumonisin concentration. Ear rot can be screened visually and so is less costly and less time-consuming to evaluate than laboratory assays for fumonisin concentration.

A periplasmic thiosulfate dehydrogenase (EC 1.8.2.2) was purified to homogeneity from the neutrophilic, obligately chemolithoautotrophic Thiobacillus sp. W5. A five-step procedure resulted in an approximately 2,300-fold purification. The purified protein had a molecular mass of 120 +/- 3 kDa, as determined by gel filtration. It is probably a tetramer containing two different subunits with molecular masses of 33 +/- 1 kDa and 27 +/- 0.5 kDa, as determined by SDS-PAGE. UV/visible spectroscopy revealed that the enzyme contained haem c; haem staining showed that both subunits contained haem c. A haem c content of 4 mol per mol of enzyme was calculated using the pyridine haemochrome test. The pH optimum of the enzyme was 5.5. At pH 7.5, the Km and Vmax were 120 +/- 10 microM and 1,160 +/- 30 U mg-1, respectively. The absence of 2-heptyl-4-hydroquinoline-N-oxide (HQNO) inhibition for the oxidation of thiosulfate by whole cells suggested that the electrons enter the respiratory chain at the level of cytochrome c. Comparison with thiosulfate dehydrogenases from other Thiobacillus species showed that the enzyme was structurally similar to the thiosulfate dehydrogenase of the acidophilic, facultatively chemolithoautotrophic Thiobacillus acidophilus, but not to the thiosulfate dehydrogenases published for the obligately chemolithoautotrophic Thiobacillus tepidarius and Thiobacillus thioparus.

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In volume 46, issue 1, p. 353-361, the estimates of heritability for fumonisin concentration and Fusarium ear rot in the NC300 3 B104 recombinant inbred population were computed incorrectly. The corrected estimates of heritability on an entry mean basis are 0.88 (SE 5 0.03) for fumonisin concentration and 0.86 (SE 5 0.03) for ear rot. The corrected estimates of heritability on a plot basis are 0.58 (SE 5 0.06) for fumonisin concentration and 0.55 (SE 5 0.07) for ear rot. The corrected estimate of heritability on an individual plant basis for ear rot is 0.22 (SE 5 0.03). The corrected estimate of the relative efficiency of indirect selection is 0.85. All of the corrected parameter estimates are higher than the original estimates reported, and the changes do not affect our conclusions.