title: Cell wall alterations in the leaves of fusariosis-resistant and susceptible pineapple cultivars.
abstract: Fusariosis, caused by the fungus Fusarium subglutinans f. sp. ananas (Syn. F. guttiforme), is one of the main phytosanitary threats to pineapple (Ananas comosus var. comosus). Identification of plant cell responses to pathogens is important in understanding the plant-pathogen relationship and establishing strategies to improve and select resistant cultivars. Studies of the structural properties and phenolic content of cell walls in resistant (Vitoria) and susceptible (Perola) pineapple cultivars, related to resistance to the fungus, were performed. The non-chlorophyll base of physiologically mature leaves was inoculated with a conidia suspension. Analyses were performed post-inoculation by light, atomic force, scanning and transmission electron microscopy, and measurement of cell wall-bound phenolic compounds. Non-inoculated leaves were used as controls to define the constitutive tissue characteristics. Analyses indicated that morphological differences, such as cell wall thickness, cicatrization process and lignification, were related to resistance to the pathogen. Atomic force microscopy indicated a considerable difference in the mechanical properties of the resistant and susceptible cultivars, with more structural integrity, associated with higher levels of cell wall-bound phenolics, found in the resistant cultivar. p-Coumaric and ferulic acids were shown to be the major phenolics bound to the cell walls and were found in higher amounts in the resistant cultivar. Leaves of the resistant cultivar had reduced fungal penetration and a faster and more effective cicatrization response compared to the susceptible cultivar.
authors.affiliation: Núcleo de Biotecnologia, Universidade Federal do Espírito Santo, Vitoria, ES 29040-090, Brazil. viegasaquije@yahoo.com.br
authors.forename: Glória Maria
authors.initials: GM
authors.lastname: de Farias Viégas Aquije
authors.forename: Poliana Belisário
authors.initials: PB
authors.lastname: Zorzal
authors.forename: David Shaun
authors.initials: DS
authors.lastname: Buss
authors.forename: José Aires
authors.initials: JA
authors.lastname: Ventura
authors.forename: Patricia Machado Bueno
authors.initials: PM
authors.lastname: Fernandes
authors.forename: Antonio Alberto Ribeiro
authors.initials: AA
authors.lastname: Fernandes
mesh_terms: D031230:Ananas / Q000737:chemistry* / Q000382:microbiology; D002473:Cell Wall / Q000737:chemistry* / Q000648:ultrastructure; D003373:Coumaric Acids / Q000737:chemistry; D005670:Fusarium / Q000472:pathogenicity; D054884:Host-Pathogen Interactions; D018625:Microscopy, Atomic Force; D008854:Microscopy, Electron; D010636:Phenols / Q000737:chemistry*; D010935:Plant Diseases / Q000382:microbiology; D018515:Plant Leaves / Q000737:chemistry* / Q000382:microbiology / Q000648:ultrastructure
chemical_list: D003373:Coumaric Acids; D010636:Phenols; C004999:ferulic acid