EFS12- Book of abstracts - Contact

SESSION 2: SECONDARY METABOLITES – BIOCHEMISTRY,
BIOSYNTHESIS, FEED AND FOOD SAFETY
Evidence for birth-and-death evolution and horizontal
transfer of a mycotoxin biosynthetic gene cluster in
Fusarium
R. H. Proctor 1 , F. Van Hove 2 , A. Susca 3 , G. Stea 3 , M. Busman 1 , T. van der
Lee 4 , C. Waalwijk 4 , T. J. Ward 1 , A. Moretti 3
1 United States Department of Agriculture, Agriculture Research Service, National Center for
Agricultural Utilization Research, Peoria, Illinois, USA; 2 Université catholique de Louvain, Earth and
Life Institute, Applied Microbiology, Mycology, Mycothèque de l’université catholique de Louvain
(BCCMTM /MUCL), Louvain-la-Neuve, Belgium; 3 National Research Council, Institute of Sciences of
Food Production, Bari, Italy; 4 Plant Research International B.V., Wageningen, The Netherlands
E-mail: francois.vanhove@uclouvain.be
In fungi, genes required for synthesis of secondary metabolites are often
clustered. The FUM gene cluster is required for synthesis of fumonisins, a family
of toxic secondary metabolites produced by species in the Fusarium (Gibberella)
fujikuroi species complex (FFSC). Fumonisins are a health and agricultural
concern because their consumption is epidemiologically associated with cancer
and neural tube defects in humans and other animals. Among FFSC species, the
FUM cluster is uniform in gene order and orientation, but located in different
genomic positions. Phylogenetic analyses indicated discord between species
phylogenies and FUM gene-based phylogenies. Subsequent constraint analyses
confirmed the discord, and analyses of variation in synonymous sites indicated
that cluster divergence predated, in some cases, and postdated, in one case,
divergence of lineages of Fusarium in which the cluster occurs. The results are
not consistent with the discord resulting from trans-species evolution of ancestral
cluster alleles, or with interspecies hybridization, but are consistent with
duplication of the cluster within an FFSC ancestor and subsequent loss and
sorting of paralogous clusters in a manner consistent with the birth-and-death
evolution seen in several multigene families. Although the results are also
consistent with horizontal transfer of the cluster, such a model is less
parsimonious because it requires multiple transfer events from unknown but
related donors to multiple FFSC recipients. However, the analyses do provide
strong support for horizontal transfer of the cluster from FFSC to another
Fusarium lineage. Thus, despite conservation of gene organization within it, the
Fusarium FUM cluster has had a complex evolutionary history.
Keywords: fumonisin, secondary metabolism, biosynthetic gene cluster
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