Study of the genetic diversity of the aflatoxin biosynthesis cluster in Aspergillus section Flavi using insertion/deletion markers in peanut seeds from Georgia, USA

Authors

Paola C. Faustinelli, National Peanut Research Laboratory, USDA-ARSFollow
Edwin R. Palencia, National Peanut Research Laboratory, USDA-ARS
Victor S. Sobolev, USDA-ARS National Peanut Research LaboratoryFollow
Bruce W. Horn, National Peanut Research Laboratory, USDA-ARSFollow
Hank T. Sheppard, National Peanut Research Laboratory, USDA-ARSFollow
Marshall C. Lamb, National Peanut Research Laboratory, USDA-ARSFollow
Xinye M. Wang, National Peanut Research Laboratory, USDA-ARS
Brian E. Scheffler, USDA ARSFollow
Jaime Martinez Castillo, Centro de Investigación Científica de YucatánFollow
Renee S. Arias, National Peanut Research LaboratoryFollow

ORCID IDs

Paola C. Faustinelli http://orcid.org/0000-0002-6925-4610

Bruce W. Horn http://orcid.org/0000-0002-0858-5424

Date of this Version

2017

Citation

MYCOLOGIA 2017, VOL. 109, NO. 2, 200–209

doi 10.1080/00275514.2017.1307095

Comments

US government work

Abstract

Aflatoxins are among themost powerful carcinogens in nature. The major aflatoxin-producing fungi are Aspergillus flavus and A. parasiticus. Numerous crops, including peanut, are susceptible to aflatoxin contamination by these fungi. There has been an increased use of RNA interference (RNAi) technology to control phytopathogenic fungi in recent years. In order to develop molecular tools targeting specific genes of these fungi for the control of aflatoxins, it is necessary to obtain their genome sequences. Although high-throughput sequencing is readily available, it is still impractical to sequence the genome of every isolate. Thus, in this work, the authors proposed a workflow that allowed prescreening of 238 Aspergillus section Flavi isolates from peanut seeds from Georgia, USA. The aflatoxin biosynthesis cluster (ABC) of the isolates was fingerprinted at 25 InDel (insertion/deletion) loci using capillary electrophoresis. All isolates were tested for aflatoxins using ultra-high-performance liquid chromatography. The neighbor- joining, three-dimension (3D) principal coordinate, and Structure analyses revealed that the Aspergillus isolates sampled consisted of three main groups determined by their capability to produce aflatoxins. Group I comprised 10 non-aflatoxigenic A. flavus; Group II included A. parasiticus; and Group III includedmostly aflatoxigenic A. flavus and the three non-aflatoxigenic A. caelatus.Whole genomes of 10 representative isolates from different groups were sequenced. Although InDels in Aspergillus have been used by other research groups, this is the first time that the cluster analysis resulting from fingerprinting was followed by whole-genome sequencing of representative isolates. In our study, cluster analysis of ABC sequences validated the results obtained with fingerprinting. This shows that InDels used here can predict similarities at the genome level. Our results also revealed a relationship between groups and their capability to produce aflatoxins. The database generated of Aspergillus spp. can be used to select target genes and assess the effectiveness of RNAi technology to reduce aflatoxin contamination in peanut.

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