A Polyphasic Approach to Compare the Genomic Profiles of Aflatoxigenic and Non-Aflatoxigenic Isolates of Aspergillus Section Flavi
Tapani Yli-Mattila; Taha Hussien; Asmaa Abbas
https://urn.fi/URN:NBN:fi-fe2021042826371
Tiivistelmä
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.
Kokoelmat
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