title: Compromised Photosynthetic Electron Flow and H2O2Generation Correlate with Genotype-Specific Stomatal Dysfunctions during Resistance against Powdery Mildew in Oats.
abstract: Stomatal dysfunction known as "locking" has been linked to the elicitation of a hypersensitive response (HR) following attack of fungal pathogens in cereals. We here assess how spatial and temporal patterns of different resistance mechanisms, such as HR and penetration resistance influence stomatal and photosynthetic parameters in oat (Avena sativa) and the possible involvement of hydrogen peroxide (H2O2) in the dysfunctions observed. Four oat cultivars with differential resistance responses (i.e., penetration resistance, early and late HR) to powdery mildew (Blumeria graminisf. sp.avenae,Bga) were used. Results demonstrated that stomatal dysfunctions were genotype but not response-type dependent since genotypes with similar resistance responses when assessed histologically showed very different locking patterns. Maximum quantum yield (Fv/Fm) of photosystem II were compromised in mostBga-oat interactions and photoinhibition increased. However, the extent of the photosynthetic alterations was not directly related to the extent of HR. H2O2generation is triggered during the execution of resistance responses and can influence stomatal function. Artificially increasing H2O2by exposing plants to increased light intensity further reduced Fv/Fm ratios and augmented the patterns of stomatal dysfunctions previously observed. The latter results suggest that the observed dysfunctions and hence a cost of resistance may be linked with oxidative stress occurring during defense induced photosynthetic disruption.
authors.affiliation: Institute for Sustainable Agriculture, Consejo Superior de Investigaciones Científicas (CSIC) Córdoba, Spain.
authors.forename: Javier
authors.initials: J
authors.lastname: Sánchez-Martín
authors.affiliation: Institute for Sustainable Agriculture, Consejo Superior de Investigaciones Científicas (CSIC) Córdoba, Spain.
authors.forename: Gracia
authors.initials: G
authors.lastname: Montilla-Bascón
authors.affiliation: Institute of Biological, Environmental and Rural Sciences, Aberystwyth University Aberystwyth, UK.
authors.forename: Luis A J
authors.initials: LA
authors.lastname: Mur
authors.affiliation: Institute for Sustainable Agriculture, Consejo Superior de Investigaciones Científicas (CSIC) Córdoba, Spain.
authors.forename: Diego
authors.initials: D
authors.lastname: Rubiales
authors.affiliation: Institute for Sustainable Agriculture, Consejo Superior de Investigaciones Científicas (CSIC) Córdoba, Spain.
authors.forename: Elena
authors.initials: E
authors.lastname: Prats
keywords: Avena sativa; hypersensitive response; oat; penetration resistance; powdery mildew; resistance cost; stomatal dysfunctions; stomatal responses to pathogens