Rust fungi are pathogens that use crops as hosts, leading to reduced yields and potentially hindering efforts to grow biomass for fuel. They are some of the most devastating pathogens of crop plants.

Igor Grigoriev and colleagues, US Department of Energy, Califronia, USA, have genetically sequenced the poplar leaf rust fungus, Melampsora larici-populina, and the wheat and barley stem rust fungus, Puccinia graminis f. sp. tritici. The two genomes were compared to identify the role rust fungi play in infecting the host plant and extract nutrients from living plant tissues.

The rust fungi genomes contain more than a thousand small effectors likely to interfere with plant perception systems and activation of defense reactions. The team believes that the fungi suppress host defense and recognition by masking their proximity to the plant and using enzymes to attach the fungal cell wall to the plant cell wall which would allow them to invade the host.

• Obligate biotrophy features unraveled by the genomic analysis of rust fungi
  S. Duplessis, C. A. Cuomo, Y.-C. Lin, A. Aerts, E. Tisserant et al.,
  Proc. Natl. Acad. Sci. 2011.
  DOI: 10.1073/pnas.1019315108