Location: Food and Feed Safety Research
Project Number: 6054-41420-009-020-S
Project Type: Non-Assistance Cooperative Agreement
Start Date: Aug 1, 2026
End Date: Jul 31, 2029
Objective:
To characterize the regulation of genetic instability in subtelomeric and centromeric regions in Aspergillus flavus through a genetic and molecular analysis. This identification of genes underlying the generation of inverted triplications will facilitate the generation of genetic and physical tools to study the elimination of toxin-producing gene clusters through subtelomeric rearrangement.
Approach:
Based on our previous collaborative studies, we have found that subtelomeric and centromeric regions display an equilibrium between mechanisms of divergence and conservation by an evolutionary comparison between different strains of A. flavus. We have subsequently identified a specific type of recombinant, an inverted triplication (TRP/INV) (a triplication in which the central repeat is inverted) that are clustered in subtelomeric and centromeric heterochromatic regions through high-depth long-read nanopore sequencing. Interestingly, very frequent short palindromic sequences clustered in heterochromatic regions are a major driver of TRP/INV formation. We have initiated a genetic analysis. In preliminary data we have found that mutations in the double-strand break-binding heterodimer Ku70/Ku80, involved in non-homologous end joining and protection of double-strand breaks from end processing, elevates the frequency TRP/INVs and leads to their excision as extrachromosomal circles. We further investigate this process by using high-depth long-read sequencing and bioinformatic analyses to test the role of micro-homology mediated recombination and epigenetic factors in TRP/INVs genesis. We will also develop a physical assay for extrachromosomal circles as a readout for TRP/INV instability.