title: Microscopic Aspects of Silicon-Mediated Rice Resistance to Leaf Scald.
abstract: This study investigated the effect of silicon (Si) on the potentiation of rice resistance against leaf scald at the microscopic level. Rice plants ('Primavera') were grown in a nutrient solution containing 0 (-Si) or 2 mM (+Si) Si. The foliar Si concentration of the +Si plants (3.6 dag/kg) increased in comparison with the -Si plants (0.3 dag/kg). An X-ray microanalysis revealed that the leaf tissue of +Si plants infected with Microdochium oryzae had higher peaks and deposition of insoluble Si than that of -Si plants. The high foliar Si concentration for the +Si plants reduced the expansion of leaf scald lesions. Scanning electron microscopy revealed that fungal hyphae and appressorium-like structures of M. oryzae were more abundant in the leaf surface of -Si plants relative to +Si plants. At both histopathological and ultrastructural levels, fungal hyphae grew abundantly into the leaf tissue of -Si plants. By contrast, rice cell walls were rarely degraded and fungal hyphae were often surrounded by amorphous granular material in the leaf tissue of +Si plants. Conidiophores emerged from stomata 36 h after fungal penetration, and conidia were noticed inside the leaf tissue of the -Si plants in great abundance. The collective results of the present study showed a high concentration and deposition of Si and a considerable deposition of phenolic-like compounds in the leaf tissue of +Si plants. These results indicate that the potentiation of the phenylpropanoid pathway in these plants supplied with Si was favorable for the increase in rice resistance to leaf scald.
authors.affiliation: Universidade Federal de Viçosa, Departamento de Fitopatologia, Laboratório da Interação Planta-Patógeno, Viçosa, Minas Gerais State, CEP 36570-900, Brazil.
authors.forename: Leonardo
authors.initials: L
authors.lastname: Araujo
authors.affiliation: Universidade Federal de Viçosa, Departamento de Fitopatologia, Laboratório da Interação Planta-Patógeno, Viçosa, Minas Gerais State, CEP 36570-900, Brazil.
authors.forename: Rayane Silva
authors.initials: RS
authors.lastname: Paschoalino
authors.affiliation: Universidade Federal de Viçosa, Departamento de Fitopatologia, Laboratório da Interação Planta-Patógeno, Viçosa, Minas Gerais State, CEP 36570-900, Brazil.
authors.forename: Fabrício Ávila
authors.initials: FÁ
authors.lastname: Rodrigues
mesh_terms: D001203:Ascomycota / Q000472:pathogenicity / Q000502:physiology*; D002473:Cell Wall / Q000378:metabolism; D060467:Disease Resistance; D004577:Electron Probe Microanalysis; D025301:Hyphae; D008855:Microscopy, Electron, Scanning; D012275:Oryza / Q000187:drug effects / Q000276:immunology* / Q000382:microbiology / Q000648:ultrastructure; D010935:Plant Diseases / Q000276:immunology* / Q000382:microbiology; D018515:Plant Leaves / Q000276:immunology / Q000382:microbiology / Q000648:ultrastructure; D054046:Plant Stomata / Q000276:immunology / Q000382:microbiology / Q000648:ultrastructure; D012825:Silicon / Q000494:pharmacology*; D013172:Spores, Fungal
chemical_list: D012825:Silicon
keywords: Monographella albescens; Oryza sativa; host defense responses