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Brachypodium distachyon-Cochliobolus sativus pathosystem is a new model for studying plant-fungal interactions in cereal crops

Zhong, Shaobin, Ali, Shaukat, Leng, Yueqiang, Wang, Rui, Garvin, David F.
Phytopathology 2015 v.105 no.4 pp. 482-489
Bipolaris sorokiniana, Brachypodium distachyon, Hordeum vulgare, Triticum aestivum, barley, blight, crossing, diploidy, disease resistance, genetic techniques and protocols, grain crops, grasses, host specificity, host-pathogen relationships, hosts, hypersensitive response, major genes, models, nucleotide sequences, plant pathogenic fungi, root rot, seeds, virulence, wheat
Cochliobolus sativus (anamorph: Bipolaris sorokiniana) causes three major diseases in barley and wheat, including spot blotch, common root rot and kernel blight or black point. These diseases significantly reduce the yield and quality of the two most important cereal crops in the US and other regions of the world. However, little is known about the molecular mechanisms underlying the pathogenicity and host specificity of the fungal pathogen as well as resistance or susceptibility of the hosts. This study aims to investigate the host status of the grass model plant Brachypodium distachyon to C. sativus and establish the B. distachyon – C. sativus interaction as a new model pathosystem for studying plant-fungal interactions in cereal crops. Six diploid B. distachyon lines (Bd1-1, Bd21, Bd21-3, Bd2-3, Bd3-1 and Bd18-1) were inoculated with five C. sativus strains (ND93-1, ND90Pr, ND85F, ND4008 and Cs07-47-1) that exhibited different virulence patterns on barley and wheat differential lines. The results indicated that all six B. distachyon lines were infected by the C. sativus strains and their susceptibility varied depending on the C. sativus strains used. A wide range of responses from a hypersensitive response (HR)-mediated resistance to full susceptibility were also observed in a large collection of B. distachyon accessions with diverse background when inoculated with four of the C. sativis isolate (ND90Pr, ND85F, ND4008 and Cs07-47-1). Genetic analysis of a F2 population derived from the cross between Bd1-1 and Bd3-1, which showed differential infection responses to Cs07-47-1, suggests that the resistance to C. sativus is controlled by major genes in B. distachyon. The availability of whole genome sequences of both the host (B. distachyon) and the pathogen (C. sativus) makes the pathosystem an attractive model for studying diseases in cereal crops.