Susceptibility of Kenyan Wheat Varieties to Head Blight, Fungal Invasion and Deoxynivalenol Accumulation Inoculated with Fusarium graminearum

Abstract

Fifteen wheat varieties commercially grown in Kenya were tested for their susceptibility to head blight and mycotoxin accumulation after inoculation with Fusarium graminearum in pot experiments. The strains of the pathogen used had been isolated from wheat collected in different growing areas of Kenya. Head blight susceptibility was assessed as the percentage of spikelets bleached and area under disease progress curve; kernel colonization by fungal mycelium was determined as ergosterol content. All varieties were found to be moderately to highly susceptible. However, the varieties differed in head blight susceptibility (29–68% of spikelets bleached; mean 54%), fungal colonization (67–187 μg/g ergosterol content; mean 111 μg/g) and the resulting mycotoxin contamination [deoxynivalenol (DON) 5–31 μg/g; mean 13.5 μg/g]. Grain weight reductions due to head blight ranged from 23 to 57% (mean 44%). The varieties could be therefore divided into partially resistant and highly susceptible genotypes. The kernels of highly susceptible varieties had higher mycotoxin and ergosterol contents. However, the kernels of some varieties contained more fungal mycelium (ergosterol) without the corresponding high amounts of DON, suggesting that they possess some resistance to DON accumulation. Less susceptible varieties showed resistance to fungal spread, as indicated by a slow disease development and lower content of fungal biomass.

Efficacy of Biological Control and Cultivar Resistance on <i>Fusarium</i> Head Blight and T-2 Toxin Contamination in Wheat

“…All tested wheat lines and cultivars were found to be usceptible to FHB concurring with the findings of other s researchers [42][43][44] who found all cultivars grown in Kenya were susceptible to FHB. However, cv.…”

Responses to selection of S5 inbreds for broad-based resistance to ear rots and grain mycotoxin contamination caused by Fusarium spp. in maize

“…Considering the same amount of disease, ELISA detected lower grain DON concentrations in pools from L7310 9 L7266 in comparison to those observed in pools from the other two populations. Intra-specific variability for DON/DS ratio had been reported in some other plant species hosting F. graminearum, such as winter rye (Perkowski et al 1995) and wheat (Muthomi et al 2002), and results from this research indicate that is also available in maize. Since genotypic correlations between disease severity and grain DON concentration were not significant, phenotypic differences observed among populations for DON/DS might arise from specific maize genes affecting ability of F. graminearum to produce DON.…”

Concentration of ergosterol in small-grained naturally contaminated and inoculated cereals

“…However, higher correlation coefficients were recorded in case of inoculated samples as the content of microflora was higher. For example, for 15 wheat cultivars inoculated with F. graminearum the correlation coefficient was 0.92 (Muthomi et al 2002). However, in case of naturally contaminated samples correlations were lower, although also significant .…”