<i>Bipolaris sorokiniana</i> , a cereal pathogen of global concern: cytological and molecular approaches towards better control‡

Summary Bipolaris sorokiniana (teleomorph Cochliobolus sativus) is the causal agent of common root rot, leaf spot disease, seedling blight, head blight, and black point of wheat and barley. The fungus is one of the most serious foliar disease constraints for both crops in warmer growing areas and causes significant yield losses. High temperature and high relative humidity favour the outbreak of the disease, in particular in South Asia's intensive 'irrigated wheat-rice' production systems. In this article, we review the taxonomy and worldwide distribution, as well as strategies to counteract the disease as an emerging threat to cereal production systems. We also review the current understanding of the cytological and molecular aspects of the interaction of the fungus with its cereal hosts, which makes B. sorokiniana a model organism for studying plant defence responses to hemibiotrophic pathogens. The contrasting roles of cell death and H(2)O(2) generation in plant defence during biotrophic and necrotrophic fungal growth phases are discussed.