Location: Food and Feed Safety ResearchTitle: Genome sequencing Louisiana Aspergillus flavus population to understand corn-fungal interaction
|GEBRU, SOLOMON - Food And Drug Administration(FDA)|
|Rajasekaran, Kanniah - Rajah|
Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 5/17/2023
Publication Date: N/A
Technical Abstract: Aspergillus flavus poses a food and feed safety risk by infecting and contaminating oil-rich seed crops with acutely toxic and carcinogenic aflatoxin. A previous population study in Louisiana revealed only 6 of 16 A. flavus vegetative compatibility groups (VCGs) infected corn. To understand genetic relatedness and conserved regions among corn infecting VCGs, genomes of isolates from 16 VCG were sequenced. The population consisted of 3 groups corresponding to sclerotial size: small (S; less than 400 µM), large (L; greater than 400 µM), mixed (M; both S and L sclerotia). L and S groups were more closely related (Fst = 0.44 ± 0.16) than both S and L groups were to the M group (Fst = 0.62 ± 0.12 and Fst = 0.67 ± 0.46, respectively). VCGs that infected corn were found in each sclerotial group, however, 4 of 6 were in the L group which included a sub-group with 2 VCGs most frequently isolated from corn (88%). Genetic relatedness also corresponded with conidial production; the 2 VCGs frequently isolated from corn produced the most conidia and were more distantly related to the most recent common ancestor between L and S and/or M groups suggesting selection for greater conidial production also favors corn infection. A total of 1840 genes were under positive selection in the L, S and M groups with 657 genes uniquely positive in the L group. It is important to investigate L group genes undergoing positive selection to understand their role in conidial production, pathogenicity and as potential silencing targets to improve resistance to A. flavus and aflatoxin contamination.