The Hemibiotrophic Apple Scab Fungus <i>Venturia inaequalis</i> Induces a Biotrophic Interface but Lacks a Necrotrophic Stage

Microscopic evidence demonstrated a strictly biotrophic lifestyle of the scab fungus <i>Venturia inaequalis</i> on growing apple leaves and characterised its hemibiotrophy as the combination of biotrophy and saprotrophy not described before. The pathogen–host interface was characterised...

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Main Authors: Ulrike Steiner, Erich-Christian Oerke
Format: Article
Language:English
Published: MDPI AG 2024-11-01
Series:Journal of Fungi
Subjects:
Online Access:https://www.mdpi.com/2309-608X/10/12/831
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author Ulrike Steiner
Erich-Christian Oerke
author_facet Ulrike Steiner
Erich-Christian Oerke
author_sort Ulrike Steiner
collection DOAJ
description Microscopic evidence demonstrated a strictly biotrophic lifestyle of the scab fungus <i>Venturia inaequalis</i> on growing apple leaves and characterised its hemibiotrophy as the combination of biotrophy and saprotrophy not described before. The pathogen–host interface was characterised by the formation of knob-like structures of the fungal stroma appressed to epidermal cells as early as 1 day after host penetration, very thin fan-shaped cells covering large parts of the host cell lumen, and enzymatic cuticle penetration from the subcuticular space limited to the protruding conidiophores. The <i>V. inaequalis</i> cell wall had numerous orifices, facilitating intimate contact with the host tissue. Pathogen-induced modifications of host cells included partial degradation of the cell wall, transition of epidermal cells into transfer cells, modification of epidermal pit fields to manipulate the flow of nutrients and other compounds, and formation of globular protuberances of mesophyll cells without contact with the pathogen. The non-haustorial biotrophy was characterised by enlarged areas of intimate contact with host cells, often mediated by a matrix between the pathogen and plant structures. The new microscopic evidence and information on the pathogens’ biochemistry and secretome from the literature gave rise to a model of the lifestyle of <i>V. inaequalis</i>, lacking a necrotrophic stage that covers and explains its holomorphic development.
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spelling doaj-art-ab9cb7e2b202436a92b56ea69f92f8132025-08-20T02:56:59ZengMDPI AGJournal of Fungi2309-608X2024-11-01101283110.3390/jof10120831The Hemibiotrophic Apple Scab Fungus <i>Venturia inaequalis</i> Induces a Biotrophic Interface but Lacks a Necrotrophic StageUlrike Steiner0Erich-Christian Oerke1Institute of Crop Science and Resource Conservation—Plant Pathology, Rheinische Friedrich-Wilhelms-Universitaet Bonn, 53115 Bonn, GermanyInstitute of Crop Science and Resource Conservation—Plant Pathology, Rheinische Friedrich-Wilhelms-Universitaet Bonn, 53115 Bonn, GermanyMicroscopic evidence demonstrated a strictly biotrophic lifestyle of the scab fungus <i>Venturia inaequalis</i> on growing apple leaves and characterised its hemibiotrophy as the combination of biotrophy and saprotrophy not described before. The pathogen–host interface was characterised by the formation of knob-like structures of the fungal stroma appressed to epidermal cells as early as 1 day after host penetration, very thin fan-shaped cells covering large parts of the host cell lumen, and enzymatic cuticle penetration from the subcuticular space limited to the protruding conidiophores. The <i>V. inaequalis</i> cell wall had numerous orifices, facilitating intimate contact with the host tissue. Pathogen-induced modifications of host cells included partial degradation of the cell wall, transition of epidermal cells into transfer cells, modification of epidermal pit fields to manipulate the flow of nutrients and other compounds, and formation of globular protuberances of mesophyll cells without contact with the pathogen. The non-haustorial biotrophy was characterised by enlarged areas of intimate contact with host cells, often mediated by a matrix between the pathogen and plant structures. The new microscopic evidence and information on the pathogens’ biochemistry and secretome from the literature gave rise to a model of the lifestyle of <i>V. inaequalis</i>, lacking a necrotrophic stage that covers and explains its holomorphic development.https://www.mdpi.com/2309-608X/10/12/831hemibiotrophyhost responsepit fieldsplasmodesmatasubcuticular developmenttransfer cells
spellingShingle Ulrike Steiner
Erich-Christian Oerke
The Hemibiotrophic Apple Scab Fungus <i>Venturia inaequalis</i> Induces a Biotrophic Interface but Lacks a Necrotrophic Stage
Journal of Fungi
hemibiotrophy
host response
pit fields
plasmodesmata
subcuticular development
transfer cells
title The Hemibiotrophic Apple Scab Fungus <i>Venturia inaequalis</i> Induces a Biotrophic Interface but Lacks a Necrotrophic Stage
title_full The Hemibiotrophic Apple Scab Fungus <i>Venturia inaequalis</i> Induces a Biotrophic Interface but Lacks a Necrotrophic Stage
title_fullStr The Hemibiotrophic Apple Scab Fungus <i>Venturia inaequalis</i> Induces a Biotrophic Interface but Lacks a Necrotrophic Stage
title_full_unstemmed The Hemibiotrophic Apple Scab Fungus <i>Venturia inaequalis</i> Induces a Biotrophic Interface but Lacks a Necrotrophic Stage
title_short The Hemibiotrophic Apple Scab Fungus <i>Venturia inaequalis</i> Induces a Biotrophic Interface but Lacks a Necrotrophic Stage
title_sort hemibiotrophic apple scab fungus i venturia inaequalis i induces a biotrophic interface but lacks a necrotrophic stage
topic hemibiotrophy
host response
pit fields
plasmodesmata
subcuticular development
transfer cells
url https://www.mdpi.com/2309-608X/10/12/831
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