Genetic fingerprinting and aflatoxin production of Aspergillus section Flavi associated with groundnut in eastern Ethiopia

Authors: MOHAMMED, ABDI - Ethiopia Haramaya University; Faustinelli, Paola; CHALA, ALEMAYEHU - Ethiopia Haramaya University; DEJENE, MASHILLA - Ethiopia Haramaya University; FININSA, CHEMEDA - Ethiopia Haramaya University; OJIEWO, CHRIS - Ethiopia Haramaya University; AYALEW, AMARE - Ethiopia Haramaya University; HOISINGTON, DAVID - University Of Georgia; Sobolev, Victor; MARTINEZ-CASTILLO, JAMIE - Centro De Investigacion Cientifica Y De Educacion Superior De Ensenada; Arias De Ares, Renee

Submitted to: BMC Microbiology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/25/2021
Publication Date: 8/28/2021
Citation: Mohammed, A., Faustinelli, P.C., Chala, A., Dejene, M., Fininsa, C., Ojiewo, C., Ayalew, A., Hoisington, D., Sobolev, V., Martinez-Castillo, J., Arias De Ares, R.S. 2021. Genetic fingerprinting and aflatoxin production of Aspergillus section Flavi associated with groundnut in eastern Ethiopia. BMC Microbiology. 21:239. https://doi.org/10.1186/s12866-021-02290-3.
DOI: https://doi.org/10.1186/s12866-021-02290-3

Interpretive Summary: There is limited information about fungal species of Aspergillus colonizing peanuts in Eastern Ethiopia. This study was done with the purpose of identifying Aspergillus species contaminating peanuts in Ethiopia, determine the capability of these fungal isolates to produce aflatoxin, identify Non-aflatoxin producing isolates, and determine the genetic diversity of the isolates. This information is part of a pipeline to generate whole-genome sequences of the predominant isolates on peanuts in order to develop new technologies.

Technical Abstract: Aspergillus species(spp)cause aflatoxin contamination, which becomes a health threat in agricultural products and leads to commodity rejection by domestic and international markets. Hence, it is necessary to discriminate diversities and aflatoxin producing species in Eastern Ethiopia, an area known by groundnut production. Therefore, the current study was undertaken to elucidate the genetic diversity of Aspergillus isolates through InDel (Insertion/Deletions) markers and evaluate in vitro aflatoxin production abilities of Aspergillus species. A total of 184 isolates of Aspergillus (A.) were used for genetic diversity fingerprinting of DNA using 23 InDel markers designed based on aflatoxin biosynthesis gene cluster. Cluster analysis was analyzed by NJ (Neighbor joining), PCoA (Principal Coordinate Analysis) and Structure cluster approaches. In addition, 122 isolates were tested for aflatoxin production using UPLC (Ultra Performance Liquid Chromatography). Aspergillus isolates studied in the current work were grouped into four main groups. Group I, the largest, concentrated almost 88% of the A. flavus and all A. flavus L strains and A. tamarii collected during the 2015 season. The 48.3% of the A. flavus collected were from peanut Fields. The highest A. flavus aflatoxin B1 producer (N1436) from the 2015 season belongs to this group and it was obtained from Gursum (77.98 µg/mL). Group II contained twenty one isolates, all A. flavus, 52.4% of which were morphotype S strains. Geographic distribution of this group was headed by isolates from Babile and Darolabu (38% each), almost all were aflatoxin B producers, and included all the A. flavus S strain found during this season (n=11) that produced only aflatoxins B with the exception of one comprised in Group I. Group III primarily included A. parasiticus (87.9%) except for four, most of which were from Darolabu (51.1%) and Gursum (42.4%). Among A. parasiticus isolates, twenty produced aflatoxins B and G as high as 50.33 µg aflatoxin G1/mL, whilst 9 isolates produced only aflatoxins type B. Group IV was represented by only six A. flavus, four of which were S strains, geographically predominant from the Darolabu district (66.7%), which were able to produce the four types of aflatoxins. In this particular season, all the Aspergillus isolated were able to produce aflatoxins. To the best of the authors’ knowledge, this is the first report of a diversity study of Aspergillus section Flavi isolated from groundnut seeds using InDel markers designed based on the Aspergillus biosynthesis gene cluster, in Easter Ethiopia. In this study, we identified molecular markers useful to detect genetic variation in Aspergillus spp. for assisting selection of candidate isolates for future DNA sequencing analyses, genetic information required to generate an exclusive Ethiopian Aspergillus spp. database and to develop effective aflatoxins control strategies in groundnut