Vegetative compatibility and phenotypic characterization as a means of determining genetic diversity of Aspergillus flavus isolates

Mitema, Alfred; Okoth, Sheila; Rafudeen, Mohamed Suhail

doi:10.1016/j.funbio.2017.11.005

Cited by 6 publications

(23 citation statements)

References 40 publications

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Section: Colonization Of Plant Tissues By Aspergillus Flavussupporting

confidence: 74%

“…The current study relates to the previous findings on Makueni maize samples [19] where they screened the strains of A. flavus isolated from maize kernels obtained from Makueni region on CAM media and found that there was significant variation in production of blue (toxigenic) and green (atoxigenic) fluorescence by most isolates. Seventy eight percent of the isolates from Makueni were observed to produce high amounts of aflatoxin AFB1, AFB2, the most potent carcinogen compared to other regions under study [19]. Additionally, studies conducted by Probst et al [24] in eastern Kenya, revealed a similar result where they performed culturebased methods to monitor and describe the population structures of aflatoxigenic fungi and its closely associated strains on maize kernels.…”

Section: Colonization Of Plant Tissues By Aspergillus Flavussupporting

confidence: 74%

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Fungal Biomass Load and Aspergillus flavus in a Controlled Environment

Mitema¹,

Feto²

2021

Biotechnological Applications of Biomass

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Fungal biomass quantification is critical in understanding the interactions between the pathogen and susceptibility or resistance of the host plant as well as identifying competition between individual fungal spp. in disease progression. In the present chapter, two maize lines grown in different climatic regions of Kenya were infected with an aflatoxigenic A. flavus isolate (KSM014) and fungal colonization of the maize plant tissues was monitored by measuring fungal biomass load after 14 days in a controlled environment. The objective of the study was to determine whether the maize line colonized was a factor in increasing or limiting the growth of an aflatoxigenic strain of Aspergillus flavus.

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Section: Colonization Of Plant Tissues By Aspergillus Flavussupporting

confidence: 74%

Section: Colonization Of Plant Tissues By Aspergillus Flavussupporting

confidence: 74%

Fungal Biomass Load and Aspergillus flavus in a Controlled Environment

Mitema¹,

Feto²

2021

Biotechnological Applications of Biomass

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“…Pildain et al [4] and Atehnkeng et al [16] ; Atehnkeng et al [11] further demonstrated that, frequencies of strains and VCGs vary by farm land and crop, and that some VCGs are frequently isolated whereas others are uncommon. VCG distribution frequency and diversity indices of the isolates were closely linked to specific regions [13] . Bock et al [41] and Cotty, [42] suggested that different A. flavus lineages might be distributed according to niche speciality adaptations and have competitive advantages in specific regions, soils, hosts or seasons.…”

Section: Discussionmentioning

confidence: 94%

“…The techniques followed were based on previous methods of Mitema and Okoth et al [13] , [28] . Briefly, the kernels were plated in triplicates on quarter strength PDA (Sigma Aldrich, USA) and incubated at 30 °C for 3 days.…”

Section: Methodsmentioning

confidence: 99%

“…Successful mating between parents of opposite mating type may occur even if they belong to different chemotypes or VCG. The determination of the VCG of a specific A. flavus strain is done by complementation tests with nitrate non-utilizing auxotroph's [9] – [13] . Members of the same VCG are presumed to have the same clonal lineage [9] – [11] , [13] , and the similarity of aflatoxin production is greater within a given VCG than between VCGs.…”

Section: Introductionmentioning

confidence: 99%

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Molecular and Vegetative Compatibility Groups Characterization of <em>Aspergillus flavus</em> Isolates from Kenya

Mitema

Feto

2020

AIMS Microbiology

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The genus Aspergillus contains diverse species and the identification is complicated. Vegetative compatibility groups (VCGs) and molecular mechanisms were deployed to study the species. The study was randomly conducted in four counties in Kenya based on the history of aflatoxicosis and maize cultivation. Thirty-seven Aspergillus flavus isolates from Nandi, Kisumu, Homa Bay and Makueni were characterized to determine their taxonomic status based on their VCGs and genotypes. A phylogenetic analysis of ITS1 and ITS2 sequences of the isolates investigated revealed ITS primers discriminating some of the A. flavus isolates as 100% sequence identity to the RefSeq . Nit mutants' complementation test revealed strong heterokaryon incompatibility between isolates of Nandi region (67%) and Makueni (33%). The trend based on VCGs and molecular findings showed high incidence of toxigenic A. flavus in Makueni, which could be the reason why the region frequently experiences chronic aflatoxicosis incidences over the last few decades as compared to other regions. Interestingly, we have discovered all S and L-morphotypes including the rare S/L-morphotypes, which implies that Kenya is home to all morphotypes of A. flavus . Thus, the analysis provides a deeper understanding of the taxonomic relationship between the A. flavus isolates and could help contextualise the data obtained for each isolate with respect to VCG genetic diversity and genotypes. Determining the primary causal agents of aflatoxin contamination is critical for predicting risk of contamination events and designing and implementing effective management strategies.

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Development and validation of TOF/Q-TOF MS/MS, HPLC method and in vitro bio-strategy for aflatoxin mitigation

Mitema

Feto

Rafudeen

2020

Food Additives & Contaminants: Part A

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Some secondary metabolites produced by fungi are carcinogenic, hepatotoxic, and/or cause birth defects in humans and animals. We developed and optimised bio-analytical tools for detection of metabolites, aflatoxins and evaluated the effectiveness of the methods in co-infected maize tissues. Isolate KSM012 (atoxigenic) demonstrated no peaks and no blue fluorescence on HPLC and TLC plates respectively confirming non-toxicity. AFB1 and AFB2 were produced by Isolate KSM015 in addition to AFG1 and AFG2, which is an indication of possible S BG morphotype. The limits of quantification and detection ranged from 0.02 to 35.81 µg/mL and 0.01-6.8 µg/mL, respectively. The best mass spectrum with lowest noise was obtained at 100% ACN and sterile water spiked with 0.1% formic acid at a flow rate of 0.3 mL/min. The positive ion mode with electrospray ionisation application exhibited better fragmentation for mycotoxins. In total 17 metabolites were detected by targeted and formula mass. KDVI maize line exhibited high fungal colonisation in comparison to GAF4 at equal co-infection ratio 50:50. AFB1 and AFG2 were remarkably higher in GAF4 in comparison to sensitive KDV1 (p ˂ 0.05). The detection limits, linearity and sensitivity showed the method developed was suitable for the determination of mycotoxin in comparisons to the guidelines of European Commission 657/EC 2002.

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Vegetative compatibility and phenotypic characterization as a means of determining genetic diversity of Aspergillus flavus isolates

Cited by 6 publications

References 40 publications

Fungal Biomass Load and Aspergillus flavus in a Controlled Environment

Fungal Biomass Load and Aspergillus flavus in a Controlled Environment

Molecular and Vegetative Compatibility Groups Characterization of <em>Aspergillus flavus</em> Isolates from Kenya

Development and validation of TOF/Q-TOF MS/MS, HPLC method and in vitro bio-strategy for aflatoxin mitigation

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