Melampsora laricis-populina

Introduction

The first symptoms are visible at the beginning and during summer in the form of  golden pustules filled with masses of spores under the leaves. Heavily infected leaves wither and die. An infected tree has an abnormal high rate of respiration and a weak photosynthesis which forces him to use up his reserves. This results in a reduced growth and badly lignified shoots that then easily freeze and become sensitive to secondary pathogens. During the next spring there are less leaves on the tree and sometimes flowering is skipped. The earlier the infection has occurred during the summer the heavier the consequences will be.

Not a single resistant poplar cultivar exists so far, since new virulent strains of Melampsora larici-populina are developed regularly. An improved understanding of the biology of Melampsora laricis-populina and the defence mechanism in poplar leaves may help to reduce the damage in plantations of the economically important poplar tree.

The JGI-DOE is currently sequencing the genome to a 8-9x depth. The initial size was estimated to be approximately 61 Mb but analysis of an initial assembly revised this estimate to approximately 95 Mb. The genome sequencing and assembly on the dicaryotic strain 98AG31 has been generated with 101.1 MB genomic sequence at an average 6.79X genome coverage. A total of 16,694 gene models were predicted by the integration of EuGene and JGI annotation pipeline. The comparison of the genomes of mutualistic (Laccaria bicolor) and pathogenic (Melampsora laricis-populina) basidiomycetes interacting with Populus will provide insights into pathogenicity/symbiosis mechanisms and into differences in evolutionary processes developed by the different types of biotrophic fungi.

Our involvement

In collaboration with:

• Joint Genome Institute
• MycorWeb, Nancy, France