Transcriptome profiling of Botrytis cinerea conidial germination reveals upregulation of infection-related genes during the prepenetration stage
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Published on: March 1, 2022
Michaela Leroch1, Astrid Kleber, Evelyn Silva
1Department of Biology, University of Kaiserslautern, Kaiserslautern, Germany.
Abstract:
Botrytis cinerea causes gray mold on a great number of host plants. Infection is initiated by airborne conidia that invade the host tissue, often by penetration of intact epidermal cells. To mimic the surface properties of natural plant surfaces, conidia were incubated on apple wax-coated surfaces, resulting in rapid germination and appressorium formation. Global changes in gene expression were analyzed by microarray hybridization between conidia incubated for 0 h (dormant), 1 h (pregermination), 2.5 h (postgermination), 4 h (appressoria), and 15 h (early mycelium). Considerable changes were observed, in particular between 0 h and 1 h. Genes induced during germination were enriched in those genes encoding secreted proteins, including lytic enzymes. Comparison of wild-type and a nonpathogenic MAP kinase mutant (bmp1) revealed marked differences in germination-related gene expression, in particular related to secretory proteins. Using promoter-GFP reporter strains, we detected a strictly germination-specific expression pattern of a putative chitin deacetylase gene (cda1). In contrast, a cutinase gene (cutB) was found to be expressed only in the presence of plant lipids, in a developmentally less stringent pattern. We also identified a coregulated gene cluster possibly involved in secondary metabolite synthesis which was found to be controlled by a transcription factor also encoded in this cluster. Our data demonstrate that early conidial development in B. cinerea is accompanied by rapid shifts in gene expression that prepare the fungus for germ tube outgrowth and host cell invasion.
Insights
Botrytis cinerea rapidly alters gene expression during germination on plant surfaces. These changes, particularly in secreted proteins, are crucial for the fungus to invade host tissues.
Area of Science:
- Plant Pathology
- Molecular Mycology
- Fungal Genetics
Background:
- Botrytis cinerea causes gray mold disease in numerous plants.
- Infection begins with airborne conidia penetrating host epidermal cells.
Purpose of the Study:
- To investigate gene expression changes in Botrytis cinerea during early development on plant-like surfaces.
- To identify genes involved in germination and host invasion.
Main Methods:
- Conidia incubated on apple wax-coated surfaces to mimic plant surfaces.
- Microarray hybridization analyzed gene expression at different developmental stages (0h to 15h).
- Promoter-GFP reporter strains used to track gene expression patterns.
Main Results:
- Significant gene expression shifts occurred within 1 hour of incubation, especially in genes encoding secreted proteins like lytic enzymes.
- A MAP kinase mutant (bmp1) showed altered germination-related gene expression.
- Specific genes (cda1, cutB) exhibited distinct expression patterns related to germination and plant lipids.
- A coregulated gene cluster potentially involved in secondary metabolite synthesis was identified.
Conclusions:
- Early conidial development in B. cinerea involves rapid transcriptional reprogramming.
- These gene expression shifts prepare the fungus for germ tube elongation and host cell invasion.
- Understanding these early events is key to developing disease control strategies.
