Polymyxa graminis is a plasmodiophorid. It is an obligate parasite of plant roots and though itself in non-pathogenic, it is responsible for the transmission of several very important plant viruses, including Barley yellow mosaic virus (BaYMV) and Soil-borne wheat mosaic virus (SBWMV).

References

• Plasmodiophorid Home Page
• Konstantin Kanyuka, Elaine Ward and Michael J. Adams. Polymyxa graminis and the cereal viruses it transmits: a research challenge. Molecular Plant Pathology, Vol 4 page 393.