Rubin indicates that by using DNA sequence to survey the forest ecosystem, from the plants to symbiotic and pathogenic fungi, researchers can ultimately optimize the conditions under which a biomass plantation would thrive. "We now have the opportunity to gain fundamental insights into plant development and growth as related to their intimate interaction which symbiotic fungi. These insights will lead to bolstered biomass productivity and improved forests."
Laccaria bicolor occurs frequently in the birch, fir, and pine forests of North America and is a common symbiont of Populus, the poplar tree whose genome was determined by the JGI in 2006 The analysis of the 65-million-base Laccaria genome, the largest fungal genome sequenced to date, yielded 20,000 predicted protein-encoding genes, almost as many as in the human genome. In sifting through these data, researchers have discovered many unexpected features, including an arsenal of small secreted proteins (SSPs), several of which are only expressed in tissues associated with symbiosis. The most prominent SSP accumulates in the extending hyphae, the tips of the fungus that colonize the roots of the host plant.
"We believe that the proteins specific to this host/fungus interface play a decisive role in the establishment of symbiosis," said Francis Martin, the Nature study's lead author. This genome exploration led Martin and his CNRS-Marseille University and DOE JGI colleagues to the unexpected observation that the genome of Laccaria lacks the enzymes involved in degradation of the carbohydrate polymers of plant cell walls but maintains the ability to degrade non-plant cell walls, which may account for Laccaria's protective capacity. These observations point towards the dual life
|Contact: David Gilbert|
DOE/Joint Genome Institute