Role of Cytokinins in Clubroot Disease Development

Clubroot, caused by the obligate biotrophic protist Plasmodiophora brassicae is a devastating disease of crucifers that causes substantial economic loss worldwide. The disease is characterized by the formation of galls in the root and hypocotyl of infected plants which restricts host vascular cambium development inhibiting efficient water and nutrient uptake by the plant. The pathogen- driven interference of hormonal homeostasis, particularly of cytokinin, in the root tissue is intricately linked with induction of hypertrophy and cell divisions leading to formation of galls. Levels of cytokinins and cell division generally increase at the onset of the disease which declines at the later stages of gall formation. The genes involved cytokinin biosynthesis such as cytokinin oxidase/ dehydrogenases and isopentenyl transferases shows differential expressions during clubroot infection and gall expansion in root tissues. Wider understanding of the roles of cytokinins and associated genes along the development of the disease will be helpful in unravelling plants defense mechanism against clubroot disease.