Abstract:
Fusarium circinatum is an economically important pathogen of pine and resides in the
Fusarium fujikuroi species complex. Here we investigated the molecular processes underlying growth
in F. circinatum by exploring the association between growth and the nutritional environment provided
by the pine host. For this purpose, we subjected a mapping population consisting of F. circinatum
X F. temperatum hybrid progeny to an analysis of growth rate on a pine-tissue derived medium.
These data, together with the available genetic linkage map for F. circinatum, were then used to
identify Quantitative Trait Loci (QTLs) associated with growth. The single significant QTL identified
was then characterized using the available genome sequences for the hybrid progeny’s parental
isolates. This revealed that the QTL localized to two non-homologous regions in the F. circinatum
and F. temperatum genomes. For one of these, the F. circinatum parent contained a two-gene deletion
relative to the F. temperatum parent. For the other region, the two parental isolates encoded different
protein products. Analysis of repeats, G+C content, and repeat-induced point (RIP) mutations
further suggested a retrotransposon origin for the two-gene deletion in F. circinatum. Nevertheless,
subsequent genome and PCR-based analyses showed that both regions were similarly polymorphic
within a collection of diverse F. circinatum. However, we observed no clear correlation between the
respective polymorphism patterns and growth rate in culture. These findings support the notion that
growth is a complex multilocus trait and raise the possibility that the identified QTL contains multiple
small-effect QTLs, of which some might be dependent on the genetic backgrounds. This study
improved our current knowledge of the genetic determinants of vegetative growth in F. circinatum
and provided an important foundation for determining the genes and processes underpinning its
ability to colonize its host environment.
Description:
SUPPLEMENTARY FILE S1: HPLC and GC-MS results showing the broad overview and primary metabolites identified in the pine-based media. SUPPLEMENTARY FILE S2: The primer sequences and PCR protocols used to amplify gene regions in this study. SUPPLEMENTARY FILE S3: Reference mapping of F. circinatum Illumina and MinIon raw reads mapped to the genomes of F circinatum KS17 and F. temperatum. SUPPLEMENTARY FILE S4: Genic information of the identified genes and indel region in the QTL region of F. circinatum. InterProScan and gene ontology information are provided for all genes in this region. Further information on the retrotransposons and repeats that are characteristic of the indel within the QTL region is provided.