A lesser-known pathogen of wheat: Bipolaris sorokiniana

The filamentous fungus Bipolaris sorokiniana (teleomorph Cochliobolus sativus) is a necrotrophic cereal pathogen of significant concern in the warm, nontraditional wheat cropping regions of Southern Asia. B. sorokiniana is also recognised as the predominant causative agent of the disease complex Helminthosporium leaf blight (HLB), comprising both B. sorokiniana and the tan spot pathogen Pyrenophora triciti-repentis. B. sorokiniana is the major constraint on wheat production in the Eastern Gangetic Plains within India, Nepal and Bangladesh and is causal to significant reductions in grain yield and quality. While efforts to identify host resistance have made headway since the early 1990s in establishing partial cultivar resistance, there remains a considerable gap in our understanding of the disease, the pathogen and the traits and mechanisms governing resistance. In the following section, we review the current status of understanding of wheat diseases caused by B. sorokiniana and their impact in the field and highlight knowledge gaps that remain unaddressed.