03/17/2008
DOE-JGI Researchers Sequence Genome of Soil Fungus Laccaria bicolor, Symbiotic Colonizer of Plant Roots
Summary
In the March 6, 2008, issue of Nature, the DOE-JGI, with French and Swedish collaborators, report the genome sequence of the fungus, Laccaria bicolor, that is intimately involved in rhizosphere colonization and symbiosis for many plants. The availability of this genome provides an unparalleled opportunity to develop a deeper understanding of the processes by which symbionts interact with plants in the carbon and nitrogen cycles, providing new insights to enhance plant productivity. This 65-megabase genome is the largest fungal genome published to date, and contains ~20,000 predicted protein-encoding genes (fewer than in the human genome). The most highly expressed of these accumulates in the proliferating hyphae colonizing the host root and may have a decisive role in the establishment of the symbiosis. Another unexpected observation is that the genome of L. bicolor lacks carbohydrate-active enzymes involved in degradation of plant cell walls, but maintains the ability to degrade non-plant cell wall polysaccharides, a capacity of potential use to bioenergy researchers. This may also enable the fungus to grow within both soil and in living plant roots. The predicted gene inventory of the L. bicolor genome points to previously unknown mechanisms of symbiosis operating in this class of fungi.