After adult MPB dispersal, aggregating beetles attempt to colonize host pine trees with the aid of symbiotic, blue-staining fungi (from the ophiostomatoid group) that they carry with them. The Tria Project has been successful in establishing vital genomic resources for fungi to assist in determining the processes by which fungi colonize a host, and the genetic features that differentiate pathogenic from only saprophytic fungus life cycles. By incorporating fungal genomics and population information into enhanced ecological risk models, we can improve our ability to estimate future spread of the MPB into forests at risk of the epidemic.
The beetles depend on the fungi to overcome host defenses and to unlock nutrients from the tree. The fungi rely on the beetles as vectors to move to new host trees. The combined activity of many beetles plus the pathogenic symbiotic fungi acts to kill the tree.
By comparing the difference in genome sequence, gene function and gene expression between a pathogenic sapstaining fungus that kills pine (Grosmannia clavigera) and a saprophytic sapstaining fungus (like Ophiostoma piceae) that only discolours processed softwood but is unable to grow in living trees, we will develop comparative genomics using high-throughput sequencing technology to yield further insights into how epidemic dynamics relate to genomic and phenotypic differences (e.g. pathogenicity and host specificity).