title: Alterations in Gas Exchange and Oxidative Metabolism in Rice Leaves Infected by Pyricularia oryzae are Attenuated by Silicon.
abstract: Rice blast, caused by Pyricularia oryzae, is the most important disease in rice worldwide. This study investigated the effects of silicon (Si) on the photosynthetic gas exchange parameters (net CO2 assimilation rate [A], stomatal conductance to water vapor [gs], internal-to-ambient CO2 concentration ratio [Ci/Ca], and transpiration rate [E]); chlorophyll fluorescence a (Chla) parameters (maximum photochemical efficiency of photosystem II [Fv/Fm], photochemical [qP] and nonphotochemical [NPQ] quenching coefficients, and electron transport rate [ETR]); concentrations of pigments, malondialdehyde (MDA), and hydrogen peroxide (H2O2); and activities of superoxide dismutase (SOD), catalase (CAT), ascorbate peroxidase (APX), glutathione reductase (GR), and lypoxigenase (LOX) in rice leaves. Rice plants were grown in a nutrient solution containing 0 or 2 mM Si (-Si or +Si, respectively) with and without P. oryzae inoculation. Blast severity decreased with higher foliar Si concentration. The values of A, gs and E were generally higher for the +Si plants in comparison with the -Si plants upon P. oryzae infection. The Fv/Fm, qp, NPQ, and ETR were greater for the +Si plants relative to the -Si plants at 108 and 132 h after inoculation (hai). The values for qp and ETR were significantly higher for the -Si plants in comparison with the +Si plants at 36 hai, and the NPQ was significantly higher for the -Si plants in comparison with the +Si plants at 0 and 36 hai. The concentrations of Chla, Chlb, Chla+b, and carotenoids were significantly greater in the +Si plants relative to the -Si plants. For the -Si plants, the MDA and H2O2 concentrations were significantly higher than those in the +Si plants. The LOX activity was significantly higher in the +Si plants than in the -Si plants. The SOD and GR activities were significantly higher for the -Si plants than in the +Si plants. The CAT and APX activities were significantly higher in the +Si plants than in the -Si plants. The supply of Si contributed to a decrease in blast severity, improved the gas exchange performance, and caused less dysfunction at the photochemical level.
authors.affiliation: First, second, third, sixth, and seventh authors: Universidade Federal de Viçosa (UFV), Departamento de Fitopatologia, Laboratório da Interação Planta-Patógeno, Viçosa, MG, 36570-900, Brazil; fourth author: EMBRAPA-National Research Center for Rice and Beans, Plant Pathology Section, Santo Antônio de Goiás, GO, 75375-000, Brazil; fifth author: UFV, Departamento de Biologia Vegetal, Brazil.
authors.forename: Gisele Pereira
authors.initials: GP
authors.lastname: Domiciano
authors.affiliation: First, second, third, sixth, and seventh authors: Universidade Federal de Viçosa (UFV), Departamento de Fitopatologia, Laboratório da Interação Planta-Patógeno, Viçosa, MG, 36570-900, Brazil; fourth author: EMBRAPA-National Research Center for Rice and Beans, Plant Pathology Section, Santo Antônio de Goiás, GO, 75375-000, Brazil; fifth author: UFV, Departamento de Biologia Vegetal, Brazil.
authors.forename: Isaías Severino
authors.initials: IS
authors.lastname: Cacique
authors.affiliation: First, second, third, sixth, and seventh authors: Universidade Federal de Viçosa (UFV), Departamento de Fitopatologia, Laboratório da Interação Planta-Patógeno, Viçosa, MG, 36570-900, Brazil; fourth author: EMBRAPA-National Research Center for Rice and Beans, Plant Pathology Section, Santo Antônio de Goiás, GO, 75375-000, Brazil; fifth author: UFV, Departamento de Biologia Vegetal, Brazil.
authors.forename: Cecília
authors.initials: C
authors.lastname: Chagas Freitas
authors.affiliation: First, second, third, sixth, and seventh authors: Universidade Federal de Viçosa (UFV), Departamento de Fitopatologia, Laboratório da Interação Planta-Patógeno, Viçosa, MG, 36570-900, Brazil; fourth author: EMBRAPA-National Research Center for Rice and Beans, Plant Pathology Section, Santo Antônio de Goiás, GO, 75375-000, Brazil; fifth author: UFV, Departamento de Biologia Vegetal, Brazil.
authors.forename: Marta Cristina Corsi
authors.initials: MC
authors.lastname: Filippi
authors.affiliation: First, second, third, sixth, and seventh authors: Universidade Federal de Viçosa (UFV), Departamento de Fitopatologia, Laboratório da Interação Planta-Patógeno, Viçosa, MG, 36570-900, Brazil; fourth author: EMBRAPA-National Research Center for Rice and Beans, Plant Pathology Section, Santo Antônio de Goiás, GO, 75375-000, Brazil; fifth author: UFV, Departamento de Biologia Vegetal, Brazil.
authors.forename: Fábio Murilo
authors.initials: FM
authors.lastname: DaMatta
authors.affiliation: First, second, third, sixth, and seventh authors: Universidade Federal de Viçosa (UFV), Departamento de Fitopatologia, Laboratório da Interação Planta-Patógeno, Viçosa, MG, 36570-900, Brazil; fourth author: EMBRAPA-National Research Center for Rice and Beans, Plant Pathology Section, Santo Antônio de Goiás, GO, 75375-000, Brazil; fifth author: UFV, Departamento de Biologia Vegetal, Brazil.
authors.forename: Francisco Xavier Ribeiro
authors.initials: FX
authors.lastname: do Vale
authors.affiliation: First, second, third, sixth, and seventh authors: Universidade Federal de Viçosa (UFV), Departamento de Fitopatologia, Laboratório da Interação Planta-Patógeno, Viçosa, MG, 36570-900, Brazil; fourth author: EMBRAPA-National Research Center for Rice and Beans, Plant Pathology Section, Santo Antônio de Goiás, GO, 75375-000, Brazil; fifth author: UFV, Departamento de Biologia Vegetal, Brazil.
authors.forename: Fabrício Ávila
authors.initials: FÁ
authors.lastname: Rodrigues
mesh_terms: D001203:Ascomycota / Q000502:physiology*; D002734:Chlorophyll / Q000378:metabolism; D000077194:Chlorophyll A; D005453:Fluorescence; D006861:Hydrogen Peroxide / Q000378:metabolism; D008315:Malondialdehyde / Q000378:metabolism; D012275:Oryza / Q000187:drug effects* / Q000382:microbiology / Q000502:physiology; D018384:Oxidative Stress; D010788:Photosynthesis / Q000187:drug effects*; D045332:Photosystem II Protein Complex / Q000378:metabolism; D010935:Plant Diseases / Q000276:immunology* / Q000382:microbiology; D018515:Plant Leaves / Q000187:drug effects / Q000382:microbiology / Q000502:physiology; D018526:Plant Transpiration / Q000187:drug effects*; D012825:Silicon / Q000494:pharmacology*
chemical_list: D045332:Photosystem II Protein Complex; D002734:Chlorophyll; D008315:Malondialdehyde; D006861:Hydrogen Peroxide; D000077194:Chlorophyll A; D012825:Silicon
keywords: Oryza sativa; fungal infection; photosynthesis