Differential protein expression in Colletotrichum acutatum: changes associated with reactive oxygen species and nitrogen starvation implicated in pathogenicity on strawberry

Abstract

The cellular outcome of changes in nitrogen availability in the context of development and early stages of pathogenicity was studied by quantitative analysis of two-dimensional gel electrophoresis of Colletotrichum acutatum infecting strawberry. Significant alterations occurred in the abundance of proteins synthesized during appressorium formation under nitrogen-limiting conditions compared with a complete nutrient supply. Proteins that were up- or down-regulated were involved in energy metabolism, nitrogen and amino acid metabolism, protein synthesis and degradation, response to stress and reactive oxygen scavenging. Members belonging to the reactive oxygen species (ROS) scavenger machinery, superoxide dismutase and glutathione peroxidase, were up-regulated at the appressorium formation stage, as well as under nitrogen-limiting conditions relative to growth with a complete nutrient supply, whereas abundance of bifunctional catalase was up-regulated predominantly at the appressorium formation stage. Fungal ROS were detected within germinating conidia during host pre-penetration, penetration and colonization stages, accompanied by plant ROS, which were abundant in the apoplastic space. Application of exogenous antioxidants quenched ROS production and reduced the frequency of appressorium formation. Up-regulation in metabolic activity was detected during appressorium formation and nutrient deficiency compared with growth under complete nutrient supply. Enhanced levels of proteins related to the glyoxylate cycle and lipid metabolism (malate dehydrogenase, formate dehydrogenase and acetyl-CoA acetyltransferase) were observed at the appressorium formation stage, in contrast to down-regulation of isocitrate dehydrogenase. The present study demonstrates that appressoria formation processes, occurring under nutritional deprivation, are accompanied by metabolic shifts, and that ROS production is an early fungal response that may modulate initial stages of pathogen development.

Induced expression of the Fragaria × ananassa Rapid alkalinization factor‐33‐like gene decreases anthracnose ontogenic resistance of unripe strawberry fruit stages

“…A, B and C) although here tissue colonization by Colletotrichum hyphae appeared less deep than in control fruits. To evaluate the fungal growth, the expression of the housekeeping gene β‐tubulin , specific to C. acutatum (Brown et al , ), was analysed by qRT‐PCR. In FaRALF‐33‐like‐ silenced red fruits the fungus grows similarly to wild‐type red fruits but less than in mock‐silenced red fruits (Fig.…”

Proteomic analysis of the phytopathogenic soilborne fungusVerticillium dahliaereveals differential protein expression in isolates that differ in aggressiveness

“…Proteasome subunit α type 1, tentatively identified in spot 8, is part of an enzyme complex that plays a role in protein processing and degradation activity 49. Proteasome subunit α type 6 has been identified in V. albo‐atrum pathotypes 9 and in Colletotrichum acutatum during appressorium stage and under nitrogen deficiency conditions 50. Activity of proteasome dgradation pathways was detected in the mycelial extract of lignin‐degrading white rot fungi 51.…”

Transcriptome Profiling of the Phaseolus vulgaris - Colletotrichum lindemuthianum Pathosystem

“…vulgaris - Colletotrichum interaction, activation of the plant defense response depends on the recognition of avirulence determinants by plant receptors. Upon recognition, specific signal transduction pathways are triggered resulting in the production of reactive oxygen species (ROS) [34]; accumulation of pathogenesis-related (PR) proteins [33]; phytoanticipins [35]; enzymes derived from host and involved in secondary metabolism [36, 37, 38]; and localized cell death [39]. …”