Molecular Plant Pathology – Pathogen Profiles

Bipolaris sorokiniana, a cereal pathogen of global concern: cytological and molecular approaches towards better control

Jagdish Kumar1, Patrick Schäfer2, Ralph Hückelhoven2, Gregor Langen2, Helmut Baltruschat2, Elke Stein2, Subramaniam Nagarajan1 and Karl-Heinz Kogel2

1 Directorate of Wheat Research, Agrasen Road, Karnal 132001, India
2 Interdisciplinary Research Centre for Environmental Sciences, Justus-Liebig-University, D-35392 Giessen, Heinrich-Buff-Ring 26–32, Germany

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 H2O2 generation in plant defence during biotrophic and necrotrophic fungal growth phases are discussed.

Disease caused by Bipolaris sorokiniana. The pathogen causes spot blotch on primary leaves of barley (A), wheat (B), and flag leaves of wheat (C). Necrotic lesions are light coloured on barley compared to darker lesions on wheat. Barley leaves develop more chlorosis as compared to wheat.