Ear rots caused by Fusarium spp. are a major concern in many maize (Zea mays L.)–growing regions of the world. Our objectives were (i) to evaluate a set of European maize inbreds for resistance to ear rots and mycotoxin concentrations, (ii) to estimate variance components and heritabilities, and (iii) to compute correlations among resistance traits. Forty‐two inbreds were evaluated for resistance to F. graminearum in four environments, and 21 inbreds were evaluated for resistance to F. verticillioides in three environments, under artificial inoculation. Data were recorded on severity of Gibberella (AGER) and Fusarium ear rots and accumulation of deoxynivalenol (DON), zearalenone, and fumonisins. Artificial inoculation was effective particularly for Gibberella ear rot. Genotypic and genotype × environment interaction variances were generally significant. Heritability estimates were moderate to high. Disease severity had strong correlations with respective mycotoxin concentrations. Selection for resistance is expected to have favorable correlated response for mycotoxins particularly with respect to AGER and DON (r p = 0.94). We recommend conducting initial selection on the basis of visual ratings and evaluate the selected elite material for mycotoxin concentrations.
Fusarium graminearum and F. verticillioides are among the most important pathogens causing ear rot of maize in Central Europe. Our objectives were to (1) compare eight isolates of each species on two susceptible inbred lines for their variation in ear rot rating and mycotoxin production across 3 years, and (2) analyse two susceptible and three resistant inbred lines for potential isolate x line interactions across 2 years by silk-channel inoculation. Ear rot rating, zearalenone (ZEA) and deoxynivalenol (DON) concentrations were evaluated for all F. graminearum isolates. In addition, nivalenol (NIV) concentrations were analysed for two NIV producers. Fumonisin (FUM) concentrations were measured for all F. verticillioides isolates. Mean ear rot severity was highest for DON producers of F. graminearum (62.9% of the ear covered by mycelium), followed by NIV producers of the same species (24.2%) and lowest for F. verticillioides isolates (9.8%). For the latter species, ear rot severities differed highly among years (2006: 24%, 2007: 3%, 2008: 7%). Mycotoxin concentrations among isolates showed a broad range (DON: 100-284 mg kg −1 , NIV: 15-38 mg kg −1 , ZEA: 1.1-49.5 mg kg −1 , FUM: 14.5-57.5 mg kg −1 ). Genotypic variances were significant for isolates and inbred lines in all traits and for both species. Isolate x line interactions were significant only for ear rot rating (P<0.01) and DON concentration (P<0.05) of the F. graminearum isolates, but no rank reversals occurred. Most isolates were capable of differentiating the susceptible from the resistant lines for ear rot severity. For resistance screening, a sufficiently aggressive isolate should be used to warrant maximal differentiation among inbred lines. With respect to F. verticillioides infections, high FUM concentrations were found in grains from ears with minimal disease symptoms.
Ear rots of maize caused by Fusarium spp. reduce grain yield and produce mycotoxins, which are harmful to humans and animals. To breed maize cultivars resistant to Fusarium spp., reliable large-scale phenotyping is essential. Our objectives were to (i) examine the precision of the ELISA method for determination of important mycotoxins, namely deoxynivalenol (DON) and fumonisins (FUM), (ii) evaluate the potential of near-infrared reflectance spectroscopy (NIRS) to estimate concentrations of DON and FUM in grain produced in inoculated maize plants, and (iii) compare the efficiency of ELISA, NIRS, and visual rating of disease severity for estimation of mycotoxin concentrations. Insignificant variation was observed between duplicate evaluations of DON and FUM by ELISA, showing the high repeatability of this method. DON and FUM determinations by ELISA were more closely correlated with mycotoxin concentrations predicted through NIRS than with visual rating of disease severity. For the prediction of DON, NIRS had very high magnitude of the coefficients of determination of calibration and cross validation (R 2 = 0.90-0.88). Thus, NIRS has a promising potential to predict DON concentration in grain samples of inoculated maize genotypes evaluated in resistance breeding programs.
Gibberella ear rot (GER), caused by Fusarium spp., is a major concern in maize production in Central Europe, and development of hybrid cultivars having GER resistance is an important breeding goal. The objectives of the present study were to (i) evaluate the variation in testcross performance (TP) of European maize germplasm for GER resistance and deoxynivalenol (DON) contamination, (ii) estimate variance components, heritabilities, and correlations of these traits, and (iii) examine the relationship between line per se performance (LP) and TP. Testcrosses of 30 diverse flint inbred lines with two dent inbred testers were evaluated in four environments under artificial inoculation. Data were recorded on severity of GER and concentration of DON. There was substantial GER development and the range of both traits was greater for LP than TP. Estimates of genotypic and genotype × environment interaction variances were significant for testcrosses with both testers. Genotypic variances were generally higher for LP than for TP in each testcross set. Correlations between LP and TP were moderate (truer^p ≤ 0.57) for GER rating and DON concentration. We recommend multi‐stage selection to develop GER resistant maize hybrids based on evaluation of GER resistance under artificial inoculation for (1) LP in one environment followed by (2) TP evaluation in two to three environments. Only the most promising testcrosses should be tested for DON concentration.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.