Why Sequence Poplar Leaf Rust?

The Populus (poplar tree) genome has been publicly released by the JGI, and the genomes of its symbiotic fungal associates Laccaria bicolor and Glomus intraradices are near completion. As part of the development of a broader community-based Populus genomics resource, and as a means of conducting informative comparative genomics among fungi, JGI will be sequencing Melampsora larici-populina (poplar leaf rust fungus), which causes widespread economic losses in poplar plantations worldwide and is a close relative of other economically important rusts (Uredinales), including Puccinia and other cereal rusts.

There is a pressing need to develop a thorough understanding of the Melampsora species that are poplar pathogens so that new control approaches can be established. In addition, an understanding of the ability of these fungi to cause disease will contribute to more general strategies to control serious diseases caused by other fungi. Moreover, the comparison of the genomes and transcriptomes of mutualistic (L. bicolor) and pathogenic (M. larici-populina) basidiomycetes interacting with Populus will provide insights into virulence/symbiosis mechanisms and into differences in evolutionary processes developed by the different types of biotrophic fungi. Overall, the sequencing will result in an unprecedented view of the complex mutualistic and pathogenic communities associated with the model tree Populus.

The perennial nature of Populus has facilitated the evolution of consortia of microorganisms, and it may be that these consortia shape individual and ecosystem responses to global climate change and other environmentally occurring biotic/abiotic stresses. Characterization of key fungal species interacting with Populus would allow in-depth exploration of the coordinated community response to these stressors, thus adding a needed dimension to climate change research and providing another step in the quest for mechanistic modeling of ecosystem responses. In addition, this project will provide unprecedented insights into the molecular bases of symbiosis, pathogenicity, and adaptation and will be a major step toward moving genomic research into the realm of ecosystem science.

CSP project participants: Francis M. Martin (proposer, INRA, France), G.K. Podila (Univ. of Alabama), R. Hamelin (Natural Resources Canada), P Rouzé (Univ. of Ghent), and S.P. DiFazio and G.A. Tuskan (Oak Ridge Natl. Lab.).