Genetic characterization of Brazilian strains of Aspergillus flavus using DNA markers

Abstract

ABSTRACT. The Aspergillus genus belongs to a filamentous fungal group characterized by wide dispersion in the environment. Some species are associated with diseases, especially in immunocompromised patients, while others are of economical importance due to aflatoxin production or biotechnological applications. Its species identification is nowadays performed by traditional techniques combined with molecular markers, resulting in a higher efficiency of isolate characterization. In the present study, internal transcribed spacer, inter-simple sequence repeats (ISSR), and random amplified polymorphic DNA (RAPD) molecular markers were used, with the aim of genetically characterizing strains of Aspergillus flavus and strains of other species of the A. flavus group. High genetic diversity was revealed by RAPD and by ISSR, in which the use of the (GACA) 4 primer yielded a higher diversity than with the (GTG) 5 primer, although the latter showed a characteristic banding profile for each species. These data were used to create a similarity matrix for the construction of dendrograms by means of the UPGMA method. The ISSR and RAPD profiles showed that among the strains previously identificated as A. flavus, one should be A. oryzae, one A. parasiticus and two A. tamarii. On the other hand, a strain previously identified as A. parasiticus should be A. flavus. All these strains 707 ©FUNPEC-RP www.funpecrp.com.br Genetics and Molecular Research 7 (3): 706-717 (2008) Genetic characterization of Aspergillus flavus strains were retested by traditional methods and their new species identification was confirmed. These results strongly support the need for using molecular markers as an auxiliary tool in differentiating fungal species and strains.

Molecular characterization of Aspergillus flavus and aflatoxin contamination of wheat grains from Saudi Arabia

“…GS for RAPD primers 1, 3, and 5 were 70.70-99.85%, 50.70-99.22%, and 60.41-99.74%, respectively, for all isolates, providing evidence of its high level of genetic diversity. High GS was revealed by RAPD and higher efficiency of the characterization of strains (Batista et al, 2008). Characterization of the seven different Aspergillus species by RAPD was useful in estimating distances between and within the same species and may help future management and conservation programs.…”

“…ISSR analysis can be useful in population genetics, epidemiological surveys and ecological studies of A. flavus. Additionally, the (GTG) 5 primer can be used to generate unique products from different Aspergillus species that can be converted to a sequence-characterized amplified region to help in taxonomic identification (Batista et al, 2008). Microsatellite analysis of the Vietnamese A. flavus strains (isolated from corn and peanut) revealed a high genetic diversity, cosmopolitan and genetically connected (Tran-Dinh et al, 2009).…”

“…flavus and aflatoxin contamination of wheat grain no clear-cut relationship between clustering in the ISSR dendrogram and geographic origin. The dendrogram produced using ISSR data has shown a high GS according to geographic origin (Batista et al, 2008). A genetic relationship was shown between the 84 strains of A. flavus isolated from Vietnam.…”

“…Consequently, RAPD allows an independence of characters, which is a clear advantage over techniques that directly or indirectly make use of restriction enzymes, such as restriction fragment length polymorphism. RAPD markers have detected genetic variability between the isolates of A. flavus and related species (Batista et al, 2008;Reddy et al, 2009;Irshad and Nawab, 2012). RAPD markers have been used to discriminate between aflatoxigenic from non-aflatoxigenic isolates of A. flavus (Lourenço et al, 2007;Gashgari et al, 2010).…”

“…These genotypes are easily compared to each other (Hadrich et al, 2011). ISSR markers are very useful for investigating the diversity and population structure of A. flavus and related species (Tran-Dinh and Carter, 2000;Batista et al, 2008;Hadrich et al, 2010;Neal et al, 2011). ISSR markers have been used to determine similarity and dissimilarity between aflatoxigenic and non-aflatoxigenic isolates of A. flavus (Hatti et al, 2010).…”