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.

Differential gene expression in response to Fusarium oxysporum infection in resistant and susceptible genotypes of flax (Linum usitatissimum L.)

“…It could be suggested that, in susceptible cultivars, changes in apoplast structure in response to F. oxysporum are more pronounced. The role of cell wall compounds in the response of flax [ 26 , 46 ] and other plant species [ 47 – 49 ] to F. oxysporum has been revealed previously. However, the present study is the first to identify the differential expression of genes related to cell wall organization or biogenesis in flax cultivars and BC 2 F 5 populations with different resistance to Fusarium wilt.…”

Physical Characteristics of the Leaves and Latex of Papaya Plants Infected with the Papaya meleira Virus

“…Physical structures or pressure differences between the surface tissues may originate from AFM tip indentations [ 16 ]. In the present study, the tip indentations causing pressure differences were avoided by using dried samples, as described by Aquije et al (2010) [ 11 ], and the images and force data obtained from each sample in air were reproducible with repeated AFM operations.…”

“…The AFM analysis of the latex samples was performed according to the procedure described by Aquije et al (2010) [ 11 ]. Twenty microliters samples of healthy and PMeV-infected papaya latex were placed on microscope slide coverslips and allowed to dry at room temperature for 1 h. The latex samples were lyophilized prior to SEM.…”

“…Light microscopy studies have been conducted to investigate the changes in papaya tissues infected with PMeV [ 7 ]. More recently, atomic force microscopy (AFM) was used to study the cell wall morphology [ 8 , 9 ] and the structural and mechanical properties of the cell walls of plants exposed to microorganisms [ 10 , 11 ].…”

Degradation of aromatic compounds through the β‐ketoadipate pathway is required for pathogenicity of the tomato wilt pathogen Fusarium oxysporum f. sp. lycopersici

“…() showed that, in response to Pythium ultimum attack, hairy roots of Ocimum basilicum secrete rosmarinic acid, a root exudate with a repellent function against an array of soil‐borne pathogens. Comparison of susceptible and resistant crop varieties also revealed that increased lignification and higher levels of phenolics can be correlated with disease resistance (de Ascensao and Dubery, ; Eynck et al ., ; de Farias Viegas Aquije et al ., ; Taddei et al ., ). In addition, several studies have reported reduced plant disease after pretreatment of the plants with various (fungal) elicitors, associated with increased lignification or increased synthesis of phenolics, such as ferulic acid (Benhamou et al ., ; Bhaskara Reddy et al ., ; He et al ., ; Takenaka et al ., ).…”