Understanding the Genetics of Clubroot Resistance for Effectively Controlling this Disease in Brassica Species

Clubroot disease is one of the most serious diseases of Brassica species, which is caused by soil-borne pathogen Plasmodiophora brassicae Woronin. Clubroot disease has a long history on vegetable crops belonging to the Brassica species; most recently, this disease is also invading rapeseed/canola crop around the globe. The clubroot disease causes significant yield and quality losses in highly infected fields. Clubroot pathogens invade into the host plant roots and infect root tissues with the formation of abnormal clubs, named as galls, which results in incompetent plant roots to intake water and nutrients and eventually dead plants. As it is a soil-borne disease and accomplishes its disease cycle in two different phases and both phases are highly efficient to damage root system as well as to release more inoculum, there are many challenges to control this disease through chemical and other cultural practices. In general, clubroot disease can be effectively managed by developing resistant cultivars. In this chapter, various resistance sources of clubroot disease in different Brassica species have been discussed with potential applications in canola/rapeseed breeding programs worldwide. Importance of gene mapping and molecular marker development efforts by different research studies for clubroot in B. rapa, B. oleracea, and B. napus has been stressed. Transcriptomic and metabolomic changes occurring during host–pathogen interac‐ tions are also covered in this chapter, which would enhance our understanding and utilization of clubroot resistance in Brassica species.