Genetic diversity analysis of Aspergillus flavus isolates from plants and air by ISSR markers

Ma, Mahmoud; Am, El-Samawaty; Ma, Yassin; Ar, Abd El-Aziz

doi:10.4238/gmr.15028081

Cited by 5 publications

(7 citation statements)

References 29 publications

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“…Considerable achievements have been made in controlling aflatoxins contamination of agricultural products following the discovery that aflatoxins are extremely toxic secondary metabolites to both humans and livestock [16,17]. This study sought to elucidate the diversity of Aspergillus species contaminating groundnuts collected at pre-and post-harvest stages from three different agroecologies of Uganda.…”

Section: Discussionmentioning

confidence: 99%

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

Acur¹,

Arias

Odongo

et al. 2020

BMC Microbiol

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Background: Groundnut pre-and post-harvest contamination is commonly caused by fungi from the Genus Aspergillus. Aspergillus flavus is the most important of these fungi. It belongs to section Flavi; a group consisting of aflatoxigenic (A. flavus, A. parasiticus and A. nomius) and non-aflatoxigenic (A. oryzae, A. sojae and A. tamarii) fungi. Aflatoxins are food-borne toxic secondary metabolites of Aspergillus species associated with severe hepatic carcinoma and children stuntedness. Despite the well-known public health significance of aflatoxicosis, there is a paucity of information about the prevalence, genetic diversity and population structure of A. flavus in different groundnut growing agroecological zones of Uganda. This cross-sectional study was therefore conducted to fill this knowledge gap. Results: The overall pre-and post-harvest groundnut contamination rates with A. flavus were 30.0 and 39.2% respectively. Pre-and post-harvest groundnut contamination rates with A. flavus across AEZs were; 2.5 and 50.0%; (West Nile), 55.0 and 35.0% (Lake Kyoga Basin) and 32.5 and 32.5% (Lake Victoria Basin) respectively. There was no significant difference (χ 2 = 2, p = 0.157) in overall pre-and post-harvest groundnut contamination rates with A. flavus and similarly no significant difference (χ 2 = 6, p = 0.199) was observed in the pre-and post-harvest contamination of groundnut with A. flavus across the three AEZs. The LKB had the highest incidence of aflatoxin-producing Aspergillus isolates while WN had no single Aspergillus isolate with aflatoxin-producing potential. Aspergillus isolates from the pre-harvest groundnut samples had insignificantly higher incidence of aflatoxin production (χ 2 = 2.667, p = 0.264) than those from the post-harvest groundnut samples. Overall, A. flavus isolates exhibited moderate level (92%, p = 0.02) of genetic diversity across the three AEZs and low level (8%, p = 0.05) of genetic diversity within the individual AEZs. There was a weak positive correlation (r = 0.1241, p = 0.045) between genetic distance and geographic distance among A. flavus populations in the LKB, suggesting that genetic differentiation in the LKB population might be associated to geographic distance. A very weak positive correlation existed between genetic variation and geographic location in the entire study area (r = 0.01, p = 0.471), LVB farming system (r = 0.0141, p = 0.412) and WN farming system (r = 0.02, p = 0.478). Hierarchical clustering using the unweighted pair group method with arithmetic means (UPGMA) revealed two main clusters of genetically similar A. flavus isolates.

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Section: Discussionmentioning

confidence: 99%

“…Allele frequencies were standardized by the lowest value and natural log-transformed while retaining zero values. Relationships among the isolates based on InDel data were determined through unweighted pair group method with arithmetic mean (UPGMA) with 1000 bootstrap replications [ 16 ], using TREECON for Windows version 1.3 b.…”

Section: Methodsmentioning

confidence: 99%

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

Acur¹,

Arias

Odongo

et al. 2020

BMC Microbiol

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“…Many Egyptian researchers are directed to explore fungal contamination and its toxin production in Egyptian crops and commodities. Most of them are emphasized on A. flavus which they have investigated in soybean [32], maize, wheat, rice, peanut seeds [33], cotton [24] and sesame [34]. We collected eight Aspergillus isolates from maize, soil, bench and air.…”

Section: Discussionmentioning

confidence: 99%

“…However, few studies have been conducted to evaluate the genotypic differences and molecular-based identification methods for Aspergillus section Flavi isolated from the Philippines [21]. On the contrary, there are many reports dealing with isolation, identification and genetic relationships between Aspergillus section Flavi isolated from Egyptian crops [22][23][24]. Within this context, the aim of this study was to (i) explore the toxins of Aspergillus section Flavi isolates using HPLC to differentiate between aflatoxigenic and non-aflatoxigenic isolates, (ii) sequence the ITS region of 26 Aspergillus isolates from different geographic origins (for molecular identification) and aflR gene (master regulatory transcription factor in the AF pathway) in 14 isolates representing both aflatoxigenic and non-aflatoxigenic isolates and (iii) find genetic relationships and molecular biodiversity among all Aspergillus isolates through RAPD and ISSR molecular markers.…”

Section: Introductionmentioning

confidence: 99%

A Polyphasic Approach to Compare the Genomic Profiles of Aflatoxigenic and Non-Aflatoxigenic Isolates of Aspergillus Section Flavi

Abbas

Hussien

Yli-Mattila

2020

Toxins

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Aflatoxins (AF) are highly toxic compounds produced by Aspergillus section Flavi. They spoil food crops and present a serious global health hazard to humans and livestock. The aim of this study was to examine the phylogenetic relationships among aflatoxigenic and non-aflatoxigenic Aspergillus isolates. A polyphasic approach combining phylogenetic, sequence, and toxin analyses was applied to 40 Aspergillus section Flavi isolates collected from eight countries around the world (USA, Philippines, Egypt, India, Australia, Indonesia, China, and Uganda). This allows one to pinpoint the key genomic features that distinguish AF producing and non-producing isolates. Based on molecular identification, 32 (80%) were identified as A. flavus, three (7.5%) as A. parasiticus, three (7.5%) as A. nomius and one (2.5%) as A. tamarii. Toxin analysis showed that 22 (55%) Aspergillus isolates were aflatoxigenic. The majority of the toxic isolates (62.5%) originated from Egypt. The highest aflatoxin production potential was observed in an A. nomius isolate which is originally isolated from the Philippines. DNA-based molecular markers such as random amplified polymorphic DNA (RAPD) and inter-simple sequence repeats (ISSR) were used to evaluate the genetic diversity and phylogenetic relationships among these 40 Aspergillus isolates, which were originally selected from 80 isolates. The percentage of polymorphic bands in three RAPD and three ISSR primers was 81.9% and 79.37%, respectively. Analysis of molecular variance showed significant diversity within the populations, 92% for RAPD and 85% for ISSR primers. The average of Polymorphism Information Content (PIC), Marker Index (MI), Nei’s gene diversity (H) and Shannon’s diversity index (I) in ISSR markers are higher than those in RAPD markers. Based on banding patterns and gene diversities values, we observed that the ISSR-PCR provides clearer data and is more successful in genetic diversity analyses than RAPD-PCR. Dendrograms generated from UPGMA (Unweighted Pair Group Method with Arithmetic Mean) cluster analyses for RAPD and ISSR markers were related to the geographic origin.

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“…Populations of A. flavus in agricultural products and foods are complex communities that may contain many different isolates (Mahmoud et al 2016). Their growth and AFB 1 production potential are known to vary (Abbas et al, 2004;Adhikari et al, 2016;Singh et al, 2015;Yogendrarajah et al, 2016;Yousefi et al, 2009).…”

Section: Introductionmentioning

confidence: 99%

Probability models for growth and aflatoxin B 1 production as affected by intraspecies variability in Aspergillus flavus

et al. 2018

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The probability of growth and aflatoxin B (AFB) production of 20 isolates of Aspergillus flavus were studied using a full factorial design with eight water activity levels (0.84-0.98 a) and six temperature levels (15-40 °C). Binary data obtained from growth studies were modelled using linear logistic regression analysis as a function of temperature, water activity and time for each isolate. In parallel, AFB was extracted at different times from newly formed colonies (up to 20 mm in diameter). Although a total of 950 AFB values over time for all conditions studied were recorded, they were not considered to be enough to build probability models over time, and therefore, only models at 30 days were built. The confidence intervals of the regression coefficients of the probability of growth models showed some differences among the 20 growth models. Further, to assess the growth/no growth and AFB/no- AFB production boundaries, 0.05 and 0.5 probabilities were plotted at 30 days for all of the isolates. The boundaries for growth and AFB showed that, in general, the conditions for growth were wider than those for AFB production. The probability of growth and AFB production seemed to be less variable among isolates than AFB accumulation. Apart from the AFB production probability models, using growth probability models for AFB probability predictions could be, although conservative, a suitable alternative. Predictive mycology should include a number of isolates to generate data to build predictive models and take into account the genetic diversity of the species and thus make predictions as similar as possible to real fungal food contamination.

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Genetic diversity analysis of Aspergillus flavus isolates from plants and air by ISSR markers

Cited by 5 publications

References 29 publications

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

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

A Polyphasic Approach to Compare the Genomic Profiles of Aflatoxigenic and Non-Aflatoxigenic Isolates of Aspergillus Section Flavi

Probability models for growth and aflatoxin B 1 production as affected by intraspecies variability in Aspergillus flavus

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