|De Saeger, Sarah|
Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 9/14/2017
Publication Date: N/A
Citation: N/A Interpretive Summary:
Technical Abstract: The genus Fusarium comprises 22 species complexes that together include approximately 300 phylogenetically distinct species. A major focus in Fusarium literature is to understand the genetic basis of niche specialization, secondary metabolites (SM) production, and host interactions in closely related species. In this study, we focused on the Fusarium incarnatum-equiseti species complex (FIESC), which comprises 31 phylogenetically distinct species, that group into two clades, the Equiseti and Incarnatum clades, in phylogenetic analysis. Members of FIESC are regarded as important plant and human pathogens, able to produce a wide range of mycotoxins, including both type A and B trichothecenes, beauvericin, butenolide, equisetin, and zearalenone. Despite their wide occurrence and toxigenic potential, little is known about inter species genome variability or the molecular organization and distribution of the SM gene clusters within the complex. Therefore, we investigated the distribution and variability of known and putative novel SM biosynthetic gene clusters within FIESC by generating and analyzing genomes of twelve members of the complex. Phylogenomic analysis, based on 26 housekeeping and whole-genome sequences, inferred phylogenies that were consistent with but more highly resolved than previously described phylogenies inferred from four genes. Genome mining of SM biosynthetic gene clusters through antiSMASH analysis showed that about 3-4% of predicted genes in a genome are involved in secondary metabolism. We confirmed production of several SMs product of several gene clusters by chemical analysis. The trichothecene cluster was present in all twelve genomes, but differed in presence, absence, and arrangement of genes relative to the cluster in the F. sambucinum species complex (FSAMSC). Overall, the number of PKS and NRPS clusters was comparable to that of other Fusarium species, ranging from 9 to 14 and from 13 to 15, respectively. Specifically, eight well-characterized SM clusters, four unknown PKS and nine unknown NRPS are shared among all the twelve genomes, while 20 other SM biosynthetic clusters are variably distributed among several genomes investigated. The distribution of some SM gene clusters among FIESC members was not always correlated with the species phylogenies. Interestingly, one NRPS-derived SM gene cluster and three PKS-derived SM gene clusters are uniquely present in FIESC among all the Fusarium species investigated to date, representing new potential SM to further investigate. Overall, our results indicate considerable variation exists in the genetic potential of FIESC members to produce SMs, including mycotoxins. The results also reveal genetic variation within FIESC that is associated with previously observed phenotypic variability.