Polymyxa graminis and the cereal viruses it transmits : a research challenge

Polymyxa graminis is a eukaryotic obligate biotrophic parasite of plant roots that belongs to a poorly studied discrete taxonomic unit informally called the 'plasmodiophorids'. P. graminis is nonpathogenic, but has the ability to acquire and transmit a range of plant viruses which cause serious diseases in cereal crop species and result in significant yield reductions. The viruses are protected from the environment within A graminis resting spores ('cysts') that may remain dormant but viable for decades (probably until a suitable host plant is encountered). The persistent, soilborne nature of these diseases makes the use of virus-resistant crop varieties currently the only practical and environmentally friendly means of control.