Research Interests:
Research Interests:
Research Interests:
Research Interests:
SummaryHuman populations in Kenya are repeatedly exposed to dangerous aflatoxin levels through consumption of contaminated crops. Biocontrol with atoxigenic Aspergillus flavus is an effective method for preventing aflatoxin in crops.... more
SummaryHuman populations in Kenya are repeatedly exposed to dangerous aflatoxin levels through consumption of contaminated crops. Biocontrol with atoxigenic Aspergillus flavus is an effective method for preventing aflatoxin in crops. Although four atoxigenic A. flavus isolates (C6E, E63I, R7H and R7K) recovered from maize produced in Kenya are registered as active ingredients for a biocontrol product (Aflasafe KE01) directed at preventing contamination, natural distributions of these four genotypes prior to initiation of commercial use have not been reported. Distributions of the active ingredients of KE01 based on haplotypes at 17 SSR loci are reported. Incidences of the active ingredients and closely related haplotypes were determined in soil collected from 629 maize fields in consecutive long and short rains seasons of 2012. The four KE01 haplotypes were among the top ten most frequent. Haplotype H‐1467 of active ingredient R7K was the most frequent and widespread haplotype in both seasons and was detected in the most soils (3.8%). The four KE01 haplotypes each belonged to large clonal groups containing 27–46 unique haplotypes distributed across multiple areas and in 21% of soils. Each of the KE01 haplotypes belonged to a distinct vegetative compatibility group (VCG), and all A. flavus with haplotypes matching a KE01 active ingredient belonged to the same VCG as the matching active ingredient as did all A. flavus haplotypes differing at only one SSR locus. Persistence of the KE01 active ingredients in Kenyan agroecosystems is demonstrated by detection of identical SSR haplotypes six years after initial isolation. The data provide baselines for assessing long‐term influences of biocontrol applications in highly vulnerable production areas of Kenya.
Research Interests:
Research Interests:
Research Interests: Microbiology, Free Radicals, Kinetics, Biology, Medicine, and 15 moreAspergillus, Peroxidase, Humans, Plants, Pathogen, Aspergillus flavus, Hydrogen Peroxide, Neutrophils, Germination, Oxygen, Hypochlorite, Myeloperoxidase, Biochemistry and cell biology, Hypochlorous acid, and Medical biochemistry and metabolomics
Research Interests:
Research Interests:
Research Interests:
Research Interests:
Research Interests: Biology and Plant Disease
Research Interests:
... by Naraqi, Laleh; Ahmadi, A`bd Ol-Reza; Sarkari, Samad; Maleki, Nasr Ol-Lah; Heydari, Asghar (2007) in Farsi. -, Studies on cotton breeding technique resistant to Fusarium and Verticillium wilts by Tan Yongjiu, Ye Pengsheng, Li... more
... by Naraqi, Laleh; Ahmadi, A`bd Ol-Reza; Sarkari, Samad; Maleki, Nasr Ol-Lah; Heydari, Asghar (2007) in Farsi. -, Studies on cotton breeding technique resistant to Fusarium and Verticillium wilts by Tan Yongjiu, Ye Pengsheng, Li Qiongfang (Jun. 2006) in Chinese. ...
Research Interests:
Cotton bolls collected from fields in the Yuma Valley during 1987 and 1988 were assayed for aflatoxin on an individual basis. Distribution of aflatoxin contaminated bolls was scattered but, generally most aflatoxin occurred in the lower... more
Cotton bolls collected from fields in the Yuma Valley during 1987 and 1988 were assayed for aflatoxin on an individual basis. Distribution of aflatoxin contaminated bolls was scattered but, generally most aflatoxin occurred in the lower half of a plant. A greater proportion of pink bollworm (PBW) damaged bolls produced seed contaminated with aflatoxins than bolls not damaged and over ge% of the total aflatoxin detected was in seed produced in PBW damaged bolls. During 1988, bolls that formed early in ~he season contained more aflatoxin than bolls that formed later. Bolls damaged by PBW early in the season when fungal inoculum was low were infected at equal or greater frequency than bolls damaged late in the season. The results suggest that protection of early bolls from PBW damage should be a component of management programs directed towards preventing aflatoxin contamination of cottonseed.
Research Interests:
Research Interests:
Research Interests:
Infection of cottonseed (Gossypium hirsutum L.) byAspergillus flavus and associated production of aflatoxins are problems in the arid portions of the United States cotton belt. The hard seed (impermeable to water) characteristic confers... more
Infection of cottonseed (Gossypium hirsutum L.) byAspergillus flavus and associated production of aflatoxins are problems in the arid portions of the United States cotton belt. The hard seed (impermeable to water) characteristic confers resistance to these problems in ripened cottonseed. Experiments were done to determine if low seed coat permeability to water or impermeability protect developing seeds from deterioration and aflatoxin formation. No differences were observed in the degree of seed deterioration in the various cotton lines that could be attributed to seed coat permeability. It is likely that, because the impermeable or low permeability phenotypes are expressed only upon seed ripening, these characteristics afford no protection to cottonseed against attack byA. flavus during seed development.
Research Interests:
ABSTRACT Transgenic Bt cotton may have reduced susceptibility to aflatoxin contamination as a result of pink bollworm resistance. During 1995 and 1996, Bt cottonseed from several commercial fields in Arizona contained aflatoxin levels... more
ABSTRACT Transgenic Bt cotton may have reduced susceptibility to aflatoxin contamination as a result of pink bollworm resistance. During 1995 and 1996, Bt cottonseed from several commercial fields in Arizona contained aflatoxin levels unacceptable for dairy use. Comparison of cottonseed with and without BGYF (bright-green-yellow fluorescence) from one highly contaminated (>6,000 ppb aflatoxin B 1) Bt seed lot indicated that most contamination probably resulted from exposure of mature cotton to high humidity. Seed exhibiting BGYF was repeatedly detected in Bt cottonseed lots but, pink bollworm exit holes were not observed in the field. A field plot test in 1996 demonstrated high resistance among Bt cultivars to both pink bollworm damage and formation of BGYF seed cotton. These observations suggest that resistance to pink bollworm will result in reduced aflatoxin contamination when pink bollworm pressure coincides with conditions conducive to Aspergillus flavus infection. However, Bt cultivars are not resistant to aflatoxin increases occurring after boll opening and large quantities aflatoxin can form during this period.
Research Interests:
Research Interests:
Research Interests:
Research Interests:
Research Interests:
Research Interests:
Research Interests:
Research Interests:
Research Interests:
Research Interests:
Research Interests:
Research Interests:
Research Interests:
Research Interests:
Research Interests:
Research Interests:
Research Interests:
Research Interests:
Research Interests:
Utilization of the three major corn reserve materials, starch, triglycerides (refined corn oil), and zein (storage protein), by Aspergillus flavus was monitored in vitro over a 7-day fermentation. Medium composition in which proportions... more
Utilization of the three major corn reserve materials, starch, triglycerides (refined corn oil), and zein (storage protein), by Aspergillus flavus was monitored in vitro over a 7-day fermentation. Medium composition in which proportions of reserve materials initially approximated proportions in mature corn kernels changed little over the first 18 h. Subsequently, hydrolysis of both starch and triglycerides occurred simultaneously, with peak concentrations of glucose and free fatty acids on day 2 of the fermentation period. Fatty acid concentrations dropped relatively rapidly after day 2 but increased again after day 6. Aflatoxin B(1) production increased after 36 h, with a peak at day 4. Aflatoxin B(1) production paralleled fungal biomass production during the exponential growth phase. A. flavus did not appear to preferentially utilize any of the released fatty acids. A number of fungus-specific metabolites were detected, including arabitol, erythritol, mannitol, trehalose, and kojic acid. Mannitol exceeded the other metabolites in concentration, and the timing of mannitol production closely paralleled that of aflatoxin B(1). Kojic acid concentrations peaked at day 6. In contrast to previously described selective use of simple carbohydrates by A. flavus, less discrimination was displayed when faced with utilization of complex substrates such as starch or triglycerides.
Research Interests:
Research Interests:
Research Interests:
Research Interests: Biology, Medicine, Europe, Maize, Mycotoxins, and 11 moreBiocontrol, Biopesticides, Ssr, Aflatoxin, Aspergillus flavus, Toxins, Aflatoxins, Crop, Mycotoxin, SSR, and Fumonisins
Research Interests: Food Science, Biology, Agriculture, Biological Control, Comparative Study, and 15 moreMedicine, Multidisciplinary, Aspergillus, Animal Feed, Animals, Applied Environmental Microbiology, Contamination, Aflatoxin, Aspergillus flavus, Fermentation, Aflatoxins, Mycotoxin, Food Contamination, Cottonseed Oil, and Gossypium
Research Interests:
An atoxigenic strain of Aspergillus flavus was applied to soils planted with cotton in Yuma, Arizona, to assess the ability of the atoxigenic strain to competitively exclude aflatoxin-producing strains during cotton boll infection and... more
An atoxigenic strain of Aspergillus flavus was applied to soils planted with cotton in Yuma, Arizona, to assess the ability of the atoxigenic strain to competitively exclude aflatoxin-producing strains during cotton boll infection and thereby prevent aflatoxin contamination of cottonseed. In both 1989 and 1990, the atoxigenic strain displaced other infecting strains during cotton boll development. Displacement was associated with significant reductions in the quantity of aflatoxins contaminating the crop at maturity. Although frequency of infected locules differed between years (1% versus 25%), in both years displacement occurred without increases in the amount of infection as measured by the quantity of locules with bright-green-yellow-fluorescence (BGYF)
Research Interests:
Research Interests:
Research Interests: Botany, Microbiology, Epidemiology, Plant Biology, Biology, and 7 moreIn Vitro, In Vivo, Spores, Plant Disease, Spore, Alternaria, and Thallophyta
The influence of amino acids on spore germination of Alternaria eassiae was investigated to develop a basis for improvement of mycoherbicide formulations. At a 1% concentration, the majority of amino acids exhibited little or no effect on... more
The influence of amino acids on spore germination of Alternaria eassiae was investigated to develop a basis for improvement of mycoherbicide formulations. At a 1% concentration, the majority of amino acids exhibited little or no effect on spore germination in vitro. However, aspartic and glutamic acids stimulated germination, and serine, tryptophan, cysteine, and phenylalanine inhibited spore germination. Cysteine was the strongest inhibitor of germination and was active in the presence of potato dextrose broth, which is normally stimulatory. One percent cysteine reduced germination 96% after 4 h. Derivitization of the mercaptan or amino group but not the carboxylic acid group diminished the ability to inhibit spore germination. Cysteine also inhibited spore germination of Alternaria crassa and Alternaria macrospora. Application of cysteine reduced development of Alternaria leaf spot on cotton plants inoculated with A. macrospora. The results demonstrate diverse effects of amino acids on spore behavior and suggest cysteine or similar compounds may be useful in preventing diseases caused by Alternaria species. Key words: amino acids, biological control, cysteine, germination, potato dextrose broth, Alternaria leaf spot.