Sclerotinia sclerotiorum (Lib) de Bary causing Sclerotinia rot in oilseed Brassicas: A review

Sclerotinia sclerotiorum (Lib.) de Bary, the causal organism of stem rot of Brassica and over 500 host plants is distributed worldwide. Selerotinia rot is menace to cultivation of oilseed Brassica crops in the world. Infection occurs on leaves, stems and pods at different developmental stages, causing seed yield losses of up to 80%, as well as significant reductions in oil content and quality. The initial mycelia infection at the base of the stem is an appearance of elongated water-soaked lesions that expand rapidly. Ascosporic (carpogenic) infection is quite general and occurs on the leaves or leaf axil. Effective pathogenesis by S. sclerotiorum requires the secretion of pathogenicity factors including oxalic acid and extracellular lytic enzymes. Germination of overwintered sclerotia, and release, survival and germination of ascospores are important factors for the development of disease and in the life cycle of this pathogen. Isolates of S. sclerotiorum show high level of morphological variability and molecular diversity. Management of S. sclerotiorum is a major challenge, and the best being the integration of various IPM measures. Partial resistance has been identified in some brassica napus and, B. Juncea, genotypes, though, wild Brassicas show better resistant reactions. This review summarizes current information on biology, physiology, epidemiology and molecular aspects of pathogenicity. In addition, current tools for research and stratagies to combat S. sclerotiorum have also been discussed.