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Published on: August 31, 2015
DHN melanin biosynthesis in the plant pathogenic fungus Botrytis cinerea is based on two developmentally regulated
1Institut für Biologie und Biotechnologie der Pflanzen (IBBP), Westfälische Wilhelms-Universität (WWU) Münster, Schlossplatz 8, 48143, Münster, Germany.
Abstract:
Botrytis cinerea is the causal agent of gray mold disease in various plant species and produces grayish macroconidia and/or black sclerotia at the end of the infection cycle. It has been suggested that the pigmentation is due to the accumulation of 1,8-dihydroxynaphthalene (DHN) melanin. To unravel its basis and regulation, the putative melanogenic and regulatory genes were identified and functionally characterized. Unlike other DHN melanin-producing fungi, B. cinerea and other Leotiomycetes contain two key enzyme (PKS)-encoding enzymes. Bcpks12 and bcpks13 are developmentally regulated and are required for melanogenesis in sclerotia and conidia respectively. BcYGH1 converts the BcPKS13 product and contributes thereby to conidial melanogenesis. In contrast, enzymes acting downstream in conversion of the PKS products (BcBRN2, BcSCD1 and BcBRN1) are required for both, sclerotial and conidial melanogenesis, suggesting that DHN melanogenesis in B. cinerea follows a non-linear pathway that is rather unusual for secondary metabolic pathways. Regulation of the melanogenic genes involves three pathway-specific transcription factors (TFs) that are clustered with bcpks12 or bcpks13 and other developmental regulators such as light-responsive TFs. Melanogenic genes are dispensable in vegetative mycelia for proper growth and virulence. However, DHN melanin is considered to contribute to the longevity of the reproduction structures.
Insights
Botrytis cinerea produces melanin for reproduction structures. Its 1,8-dihydroxynaphthalene (DHN) melanin pathway involves unique enzymes and transcription factors, crucial for conidia and sclerotia development.
Area of Science:
- Mycology
- Plant Pathology
- Biochemistry
Background:
- Botrytis cinerea causes gray mold disease in plants.
- Pigmentation in B. cinerea is attributed to 1,8-dihydroxynaphthalene (DHN) melanin.
- Understanding DHN melanin biosynthesis and regulation is key to controlling plant diseases.
Purpose of the Study:
- To identify and functionally characterize genes involved in DHN melanin production and regulation in Botrytis cinerea.
- To elucidate the specific roles of key enzymes and transcription factors in the melanogenesis pathway.
- To investigate the unusual non-linear pathway of DHN melanogenesis in B. cinerea.
Main Methods:
- Gene identification and functional characterization of putative melanogenic and regulatory genes.
- Analysis of developmental regulation of melanin-related genes.
- Investigation of enzyme activities and downstream product conversions.
Main Results:
- B. cinerea possesses two key polyketide synthase (PKS)-encoding enzymes, Bcpks12 and bcpks13, for melanogenesis.
- Bcpks12 and bcpks13 are developmentally regulated and essential for sclerotial and conidial melanogenesis, respectively.
- DHN melanogenesis in B. cinerea follows an unusual non-linear pathway regulated by specific transcription factors.
Conclusions:
- DHN melanin is not essential for vegetative growth or virulence but contributes to the longevity of reproductive structures in B. cinerea.
- The identified genes and regulatory mechanisms provide insights into fungal pigmentation and development.
- This study reveals a unique DHN melanin pathway in Leotiomycetes, distinct from other fungi.
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