Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 9/10/2011
Publication Date: N/A
Citation: Interpretive Summary:
Technical Abstract: The Fusarium trichothecenes nivalenol (NIV) and deoxynivalenol (DON) are among the mycotoxins of greatest concern to agricultural production and food/feed safety worldwide. Previous analyses indicate that during early evolution of the Fusarium incarnatum-F. equiseti species complex (FIESC), the trichothecene biosynthetic gene (TRI) cluster underwent marked rearrangements, including gene loss, changes in gene position and orientation, and relocation of genes into the cluster from elsewhere in the genome. Here, additional analyses revealed that in most FIESC isolates the cluster gene TRI1 is almost entirely deleted. Nevertheless, TRI1 is intact in some isolates. In the morphologically defined FIESC species F. camptoceras, two cluster genes, TRI7 and TRI13, have multiple insertions and deletions that render them nonfunctional. Nonfunctionalization of TRI7 and TRI13 is responsible for the change from NIV-like to DON-like trichothecene production in the Fusarium graminearum species complex (FGSC), a lineage that is phylogenetically distinct from FIESC. If nonfunctionalization of TRI7 and TRI13 arose once in a common ancestor of FGSC and FIESC, the nonfunctional alleles would have had to persist during divergence of the two lineages and rearrangement of the TRI cluster in FIESC. These findings suggest that TRI7 and TRI13 nonfunctionalization and concomitant changes in trichothecene production arose independently in F. camptoceras and FGSC and thereby represent convergent evolution of trichothecene biosynthesis in different lineages of Fusarium.