Resistance of Kenyan wheat germplasm to Fusarium head blight and deoxynivalenol contamination (original) (raw)
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Fusarium head blight (FHB) of wheat causes quantitative and qualitative reduction in yield. Cultivar resistance is the most effective method of managing the disease. This study evaluated the resistance of wheat germplasm currently available in Kenya to Fusarium head blight and deoxynivalenol (DON) contamination. Nine wheat varieties and four CIMMYT lines were evaluated for susceptibility to FHB under two diverse agro-ecologies in Nakuru and Narok Counties, Kenya during the 2013 cropping season and in the greenhouse. The varieties and lines were inoculated at mid-anthesis with mixed inocula of three isolates of F. graminearum. Incidence and severity of FHB were assessed weekly and data on severity used to calculate the area under disease progress curve (AUDPC). After harvest, incidence of F. graminearum in the grain was determined and DON contamination determined by direct competitive enzyme-linked immunosorbent assay (ELISA). Incidence and severity of FHB differed significantly (p ≤ 0.05) among the varieties and lines with variety Kwale showing the least disease while line 10155 had the highest FHB levels. The AUDPC ranged from 69.8 to 120.1 for the least and most susceptible varieties, respectively. All the wheat lines and varieties accumulated DON ranging from 442 to 748 ng/g (Mean = 572 ng/g). There was a positive correlation between FHB severity, AUDPC, re-isolation frequency of F. graminearum and DON accumulation. The assessed wheat varieties and lines could be grouped into two categories: moderately tolerant and susceptible. Wheat varieties and lines available in Kenya are susceptible to FHB and DON contamination implying need for considering other strategies for managing FHB.
Fusarium head blight (FHB) is an important disease of small grain cereals. This study assessed the incidence and severity of FHB of wheat at hard dough stage, and levels of deoxynivalenol and T2-toxin at harvest by direct competitive enzyme linked immuno-sorbent assay. Wheat ears were randomly sampled from 51 farms in Narok County and 51 farms in Nakuru County at hard dough stage while wheat kernels were sampled at harvest. Prevalence of FHB in both Counties was 100%. The mean incidence of FHB was 28.4% and 20.5% in Narok and Nakuru Counties, respectively with 16.9% and 11.7% corresponding severity. Over 14 Fusarium spp. were isolated from wheat ears and kernels with F. avenaceum, F. poae and F. graminearum being isolated in the highest incidence. Levels of DON in the kernels ranged from below limit of detection (<LOD) to 623 µg/kg while the concentration of T-2 toxin ranged from <LOD to 69 µg/kg. The levels of DON and T2-toxin in wheat kernels in the two Counties were within the limits set by the European Commission and the United States Food and Drug Administration. The relatively low incidence and severity of FHB correlated with the low levels of DON and T-2 toxin in harvested wheat grains. There is however need to continuously monitor occurrence of FHB and toxin levels in wheat which varies among seasons due to variability in climatic conditions.
Role of agronomic practices on the occurrence of Fusarium head blight of wheat
2014
Fusarium head blight is a disease of small grain cereals that reduces yield and causes mycotoxin contamination. The role of agronomic practices on the occurrence of wheat agronomic practices was studied. In the experiment, a survey to determine wheat production practices was conducted in four agro-ecological zones in 2013 cropping season. Fusarium head blight incidence and severity was determined in four 1m quadrants by counting infected heads and the proportion of diseased head respectively. Fungal contamination was determined by isolation on agar media and identified based on morphological and cultural characteristics. Majority of the farmers planted variety Njoro BW2, obtained certified seeds from Kenya Agricultural research institute, practiced crop rotation and applied soil amendments. Fusarium head blight occurrence was prevalent in all the regions but severity and incidence were low with Fusarium graminearum, F. avenaceum and F. poae isolated as the major causal agents. Wheat...
Phytopathology, 2012
Fusarium head blight (FHB), caused by Fusarium graminearum sensu stricto (s.s.), causes tremendous annual yield losses in wheat worldwide. Variation of aggressiveness of isolates from individual field populations in terms of FHB infection and deoxynivalenol (DON) concentration in the host are important population parameters reflecting parasitic ability. Our main objective was to estimate the variation of both traits within three populations of F. graminearum s.s., each consisting of 30 single-spore isolates collected from small wheat fields in Germany, and to compare it with 11 isolates of a collection (F. graminearum collection) from four countries. The same isolates were characterized using 19 single-sequence repeat markers. All isolates were spray inoculated on a moderately resistant spring wheat cultivar at two field locations over 2 years (i.e., in four environments). The genotypic proportion of phenotypic variance (σ2G) within populations was significant (P < 0.01) for both...
Evaluation of wheat genotypes resistance to Fusarium head blight in Paraguay
Pesquisa Agropecuária Tropical
Fusarium head blight (FHB), or scab, caused by a Fusarium spp. complex, is an important wheat disease in Paraguay. Among the strategies used to control it, the genetic resistance is considered highly efficient and cost effective. This study aimed to evaluate and compare the effects of F. graminearum on six wheat genotypes, including two comparison varieties, in two seeding dates. The genotypes were artificially inoculated in the spike, at the flowering stage, by injecting a pool of four pathogenic F. graminearum isolates. The FHB development was evaluated by scoring the disease incidence and severity, percentage of diseased spikelets and damaged kernels, as well as using the area under the disease progress curve. Besides the kernel infection, its impact on the development of mycotoxins (deoxynivalenol) and interactions with the genotypes were also evaluated. The results identified an advanced breeding line (Lin 84) with a resistance level to FHB comparable to that of the universally...