Plasmodiophora brassicae–The causal agent of clubroot and its biological control/suppression with fungi–A review

Clubroot, as a major disease and severe threat to cruciferous crops, is caused by the pathogen Plasmodiophora brassicae Woronin. The pathogen is an obligate biotrophic protist and plasmodiophorid in the eukaryotic kingdom of Rhizaria. P. brassicae can infect almost all species of family Brassicaceae, resulting in yield and quality losses of these important oil and vegetable producing crops worldwide. Resting spores of the pathogen can persist in soil for more than 18 years and can easily be transmitted through a number of agencies, including infected transplants and animals. Furthermore, resting spores can rapidly increase with continuous cropping system devastating both protected vegetables and infected fields. Cruciferous crops such as Canola and others are of enormous importance, as they are important source of vegetable oil for human and industrial lubricants, where mineral oils are inappropriate. Several strategies are in practice such as adjustment of soil pH, soil liming, controlling the soil environment and changes in hormonal levels etc. for suppression and/or controlling clubroot disease. But these are conventional techniques impractical under most circumstances and insufficient for controlling the disease. Thus, the use of fungi could be a possible promising strategy for suppression/controlling clubroot disease in economically important plants. This review summarizes the historical background of clubroot, current knowledge about its pathogen life cycle, its host range, problems in controlling the spreading of disease as well as the recent attempts for suppression/controlling the pathogen via beneficial endosymbiont fungi.