scholarly journals Genetic diversity of aflatoxin-producing Aspergillus flavus isolated from selected groundnut growing agro-ecological zones of Uganda

2020 ◽  
Vol 20 (1) ◽  
Author(s):  
Amos Acur ◽  
Renée S. Arias ◽  
Steven Odongo ◽  
Samuel Tuhaise ◽  
Joseph Ssekandi ◽  
...  
Keyword(s):  
Genetic Diversity ◽  
Aspergillus Flavus ◽  
Ecological Zones ◽  
Agro Ecological Zones

scholarly journals Genetic diversity of aflatoxin-producing Aspergillus flavus isolated from groundnuts in selected agro-ecological zones of Uganda

2019 ◽  
Author(s):  
Amos Acur ◽  
Renée S. Arias ◽  
Steven Odongo ◽  
Samuel Tuhaise ◽  
Joseph Ssekandi ◽  
...  
Keyword(s):  
Genetic Diversity ◽  
Aspergillus Flavus ◽  
Lake Victoria ◽  
Farming System ◽  
Aspergillus Species ◽  
Lake Victoria Basin ◽  
West Nile ◽  
Ecological Zones ◽  
Post Harvest ◽  
Agro Ecological Zones

Abstract Background Aspergillus is the main fungal genus causing pre- and post-harvest contamination of groundnuts. Aspergillus flavus belongs to section Flavi, a group consisting of both the aflatoxigenic species (A. flavus, A. parasiticus and A. nomius) and non-aflatoxigenic species (A. oryzae, A. sojae and A. tamarii). Aflatoxins are food-borne toxic secondary metabolites produced by Aspergillus species, causing hepatic carcinoma and stunting in children and are the most toxic carcinogenic mycotoxins ever identified. Despite the well-known public health problems associated with aflatoxicosis in Uganda, information about the genetic diversity of the main aflatoxin causing fungus, Aspergillus flavus in this country is still limited. Results A cross-sectional survey was therefore carried out in three main groundnut-growing agro-ecological zones (AEZs) of Uganda; West Nile farming system, Lake Kyoga basin mixed farming system and Lake Victoria basin farming system. This was to assess the genetic diversity of A. flavus and to establish the contamination rates of groundnuts with Aspergillus species at pre- and post-harvest stages. Out of the 213 A. flavus isolates identified in this study, 96 representative isolates were fingerprinted using 16 insertion/deletion microsatellite markers. Data from fingerprinting were analyzed through Neighbor Joining while polymorphism was determined using Arlequin v 3.5. The pre- and post-harvest contamination rates were; 2.5% and 50.0% (West Nile farming system), 55.0% and 35.0% (Lake Kyoga basin mixed farming system) and 32.5% and 32.5% (Lake Victoria basin farming system) respectively. The Chi-square test showed no significant differences between pre- and post-harvest contamination rates among AEZs (p = 0.199). Only 67 out of 96 isolates produced suitable allele scores for genotypic analysis. Analysis of genetic diversity showed higher variation within populations than among populations. Two major clusters (aflatoxigenic and non-aflatoxigenic isolates) were identified as colonizing groundnuts at pre- and post-harvest stages. Conclusions These findings provide a first insight on the existence of non-aflatoxigenic strains of A. flavus in Uganda. These strains are potential candidates for developing local Aspergillus bio-control agent.

Genetic Diversity of Aphid (Hemiptera: Aphididae) Species Attacking Amaranth and Nightshades in Different Agro-Ecological Zones of Kenya and Tanzania

2018 ◽  
Vol 26 (2) ◽  
pp. 407-421
Author(s):  
A.C. Kipnyargis ◽  
F.M. Khamis ◽  
E.U. Kenya ◽  
S. Ekesi ◽  
K.K.M. Fiaboe
Keyword(s):  
Genetic Diversity ◽  
Ecological Zones ◽  
Agro Ecological Zones

scholarly journals GENETIC STRUCTURATION OF SITOPHILUS ZEAMAIS SUBSERVIENT TO MILLET ACCORDING TO AGRO ECOLOGICAL ZONES OF SENEGAL (WEST AFRICA)

2019 ◽  
pp. 41-48
Author(s):  
Ngagne Demba SARR ◽  
Toffène DIOME ◽  
Cheikh THIAW ◽  
Mbacké SEMBENE
Keyword(s):  
Genetic Diversity ◽  
Cytochrome B ◽  
Insect Pests ◽  
Sitophilus Zeamais ◽  
Genetic Structuring ◽  
Ecological Zones ◽  
Agroecological Zones ◽  
Climatic Characteristics ◽  
Agroecological Zone ◽  
Agro Ecological Zones

In Senegal, millet is the most exploited cereal and the second most one consumed after rice. It is cultivated in most agroecological zones whose more or less arid climatic characteristics favor the development of several insect pests, among which Sitophilus Zeamais, a beetle of the Curculionidae. This insect causes a lot of losses of millet stocks, mainly in four agro-ecological zones: NBA , SBA , SOHC and BMC . Our study aims to highlight a possible genetic structuring of Sitophilus Zeamais subservient to millet according to these agroecological zones. The advantage of the existence of a genetic differentiation between agroecological zones is to be able to detect after the degree of genetic homogeneity of each one of them and consequently their impacts on the survival or the extinction of the insect, because the genetic diversity of populations influences their adaptive potentials. To achieve this goal, we sampled Sitophilus Zeamais insects subservient to millet in each agroecological zone. 43 individuals were harvested in total. The exploitation of the sequences of the cytochrome b gene corresponding to these individuals has highlighted a genetic structuration of Sitophilus Zeamais subservient to millet according to the 4 agroecological zones, attested by the values of genetic distance, Fst ones and corroborated by the results of the test. AMOVA. KEYWORDS : Sitophilus Zeamais, cytochrome b, millet, genetic structuring.

scholarly journals Bio-competitive exclusion: efficacy of non-aflatoxigenic Aspergillus section Flavi-L morphotypes in control of aflatoxigenic Aspergillus flavus in groundnuts (Arachis hypogaea L.)

2021 ◽  
Vol 10 (1) ◽  
Author(s):  
Anyway Chofamba
Keyword(s):  
Aspergillus Flavus ◽  
Competitive Exclusion ◽  
Control Mechanism ◽  
Aflatoxin Contamination ◽  
Practical Applications ◽  
Ecological Zones ◽  
Arachis Hypogaea L ◽  
Aflatoxin B ◽  
Biological Control Mechanism ◽  
Agro Ecological Zones

Abstract Background The biological control mechanism of Aspergillus flavus (aflatoxigenic) strains in groundnuts with atoxigenic strains from the same species through competitive exclusion employed the use of endemic and well-adapted strains within the agro-ecological zones of Zimbabwe. The selected elite non-aflatoxigenic isolates of A. flavus native to Zimbabwe were evaluated for their capability to reduce aflatoxin contamination in groundnuts under laboratory conditions. Results Average reduction percentages in aflatoxin B concentration for the 2019 and 2020 set of experiments ranged from 91.6 ± 3.4 to 95.8 ± 3.1% and 90.29 ± 3.6% to 95.29 ± 4.1%, respectively. Levels of aflatoxin in the co-inoculation research experiments administered were significantly reduced in all the experimental units carried out. Treatment efficiencies of the tested isolates in this study at 4:1 and 2:1 ranged from 1.20 to 2.52 and from 1.02 to 1.21, respectively. The efficacy of the tested non-aflatoxigenic strains against the aflatoxigenic strain native to Zimbabwe (ZMW 0127) indicates that the non-aflatoxigenic isolates of A. flavus. have sound practical applications against vast communities of aflatoxin-producing fungi across all the agro-ecological zones in Zimbabwe. Conclusion The recognized non-aflatoxigenic isolates will be of an incentive as dynamic active ingredients in biocontrol formulations for the decrease in aflatoxins in groundnuts grown in Zimbabwe.

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