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Histochemical Characterization of Early Response to Cochliobolus sativus Infection in Selected Barley Genotypes

July 2014 , Volume 104 , Number  7
Pages  715 - 723

Susana Rodríguez-Decuadro, Paula Silva, Oscar Bentancur, Fernanda Gamba, and Clara Pritsch

First, second, and fifth authors: Departamento de Biología Vegetal, third author: Departamento de Biometría y Estadística, and fourth author: Departamento de Protección Vegetal, Facultad de Agronomía, Universidad de la República, Garzón 780, Montevideo 12900, Uruguay.

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Accepted for publication 20 January 2014.

Much effort is being made to breed barley with durable resistance to leaf spot blotch incited by Bipolaris sorokiniana (teleomorph: Cochliobolus sativus). We hypothesized that susceptibility and resistance traits in 11 diverse barley genotypes inoculated with a single C. sativus isolate might specify a range of distinct host cell responses. Quantitative descriptions of interaction microphenotypes exhibited by different barley genotype seedlings after infection with C. sativus are provided. Early oxidative responses occurring in epidermis and mesophyll leaf tissue were monitored by histochemical analysis of H2O2 accumulation at 8, 24, and 48 h after inoculation. Cell wall apposition (CWA) in epidermal cells and hypersensitive reaction (HR) of epidermal or mesophyll tissue were early defenses in both resistant and susceptible genotypes. There were differences in level, duration, and frequency of occurrence for CWA and HR for the different barley genotypes. Occurrence of HR in epidermal cells at post-penetration stages was indicative of compatibility. Patterns of cell responses were microphenotypically diverse between different resistant and susceptible genotypes. This suggests that timing and level of response are key features of microphenotypic diversity that distinguish different functional mechanisms of resistance and susceptibility present in barley.

© 2014 The American Phytopathological Society