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

item Faustinelli, Paola
item Palencia, Edwin
item Wang, Xinye
item Sobolev, Victor
item Horn, Bruce
item Sheppard, Harry - Hank
item Lamb, Marshall
item Scheffler, Brian
item MARTINEZ-CASTILLO, JAIME - Yucatan Center For Scientific Research
item Arias De Ares, Renee

Submitted to: Mycologia
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/30/2017
Publication Date: 4/12/2017
Citation: Faustinelli, P.C., Palencia, E.R., Wang, X.M., Sobolev, V., Horn, B.W., Sheppard, H.T., Lamb, M.C., Scheffler, B.E., Martinez-Castillo, J., Arias De Ares, R.S. 2017. Study of the genetic diversity of the aflatoxin biosynthesis cluster in Aspergillus section Flavi using insertion/deletion markers in peanut seeds from Georgia, USA. Mycologia. doi:10.1080/00275514.2017.1307095.

Interpretive Summary: A workflow was developed to study genetic diversity of Aspergillus section flavi. A preliminary screening with 25 insertion/deletion (InDel) loci, was followed b whole genome sequencing of representative isolates of these fungi. This approach will provide a tool to obtain representative DNA sequences of these fungi in different geographic areas where molecular tools for the control of aflatoxins needs to be developed.

Technical Abstract: Aflatoxins are among the most 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 included mostly 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.