Home • Melampsora allii-populina 12AY07 v1.0
Photo of Melampsora allii-populina 12AY07 v1.0
Urediniospores and paraphyses of Melampsora allii- populina (Photos: © Pascal Frey, INRA Nancy).
Photo of Melampsora allii-populina 12AY07 v1.0
Uredinia of Melampsora allii­populina forming orange pustules on a poplar leaf (Photo: © Pascal Frey, INRA Nancy).

Melampsora allii­-populina is a rust fungus (Pucciniales) that belongs to the Melampsoraceae family and is closely related to  Melampsora larici­-populina, the first poplar rust fungus sequenced by the Joint Genome Institute. Both rust fungi can cause damage in poplar plantations. Rust fungi are obligate biotrophs and have the most complex life cycle known in fungi with one or two alternate host species and up to five distinct spore forms (sexual and asexual). Both poplar rust fungi sequenced by JGI are heteroecious and share poplar as a telial host, on which they produce large amounts of asexual spores (urediniospores) responsible for epidemics. Interestingly, they possess different aecial hosts on which they perform sexual reproduction, i.e. Allium spp., Arum spp. and Muscari spp. (all of which are monocots) for M. allii­-populina and Larix spp. (conifers) for M. larici­-populina.

The genome of M. allii­-populina was sequenced in the frame of the JGI 1000 Fungal Genomes Project to explore the molecular bases of host adaptation by identifying the common sets of genes that are necessary to infect poplar and those that differ and may be specific to infection of Allium and Larix.

Rust fungi are notorious for their large genome size compared to other basidiomycetes. M. allii­-populina represents one of the largest fungal genomes sequenced to date, at ~336Mb. Additionally, this genome is quite a bit larger than  the two relatives already sequenced in the Melampsoraceae family (i.e. ~110 Mb for M. larici-populina and ~190 Mb for the flax rust M. lini). Some of this difference may be due to the sequencing platform, as M. allii-populina is the first member of this  family sequenced with PacBio.