Mr-lac3 and Mr-lcc2 in <i>Metarhizium robertsii</i> Regulate Conidiation and Maturation, Enhancing Tolerance to Abiotic Stresses and Pathogenicity
As a type of multicopper oxidase, laccases play multiple biological roles in entomopathogenic fungi, enhancing their survival, development, and pathogenicity. However, the mechanisms by which laccases operate in these fungi remain under-researched. In this study, we identified two laccase-encoding g...
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| Main Authors: | , , , , , , , , |
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| Format: | Article |
| Language: | English |
| Published: |
MDPI AG
2025-02-01
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| Series: | Journal of Fungi |
| Subjects: | |
| Online Access: | https://www.mdpi.com/2309-608X/11/3/176 |
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| Summary: | As a type of multicopper oxidase, laccases play multiple biological roles in entomopathogenic fungi, enhancing their survival, development, and pathogenicity. However, the mechanisms by which laccases operate in these fungi remain under-researched. In this study, we identified two laccase-encoding genes, <i>Mr-lac3</i> and <i>Mr-lcc2</i>, from <i>Metarhizium robertsii</i>, both of which are highly expressed during conidiation. Knocking out <i>Mr-lac3</i> and <i>Mr-lcc2</i> resulted in a significant increase in the conidial yields of <i>M. robertsii</i>. Furthermore, the relative expression levels of upstream regulators associated with the conidiation pathway were markedly up-regulated in <i>ΔMr-lac3</i> and <i>ΔMr-lcc2</i> compared to the wild-type strain during conidiation, indicating that <i>Mr-lac3</i> and <i>Mr-lcc2</i> negatively regulate conidia formation. qRT-PCR analyses revealed that <i>Mr-lac3</i> and <i>Mr-lcc2</i> are regulated by the pigment synthesis gene cluster, including <i>Mr-Pks1</i>, <i>Mr-EthD</i>, and <i>Mlac1</i>, and they also provide feedback regulation to jointly control pigment synthesis. Additionally, <i>ΔMr-lac3</i> and <i>ΔMr-lcc2</i> significantly reduced the trehalose content in conidia and increased the sensitivity to cell wall-perturbing agents, such as Congo red and guaiacol, which led to a marked decrease in tolerance to abiotic stresses. In conclusion, the laccases Mr-lac3 and Mr-lcc2 negatively regulate conidia formation while positively regulating conidial maturation, thereby enhancing tolerance to abiotic stresses and pathogenicity. |
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| ISSN: | 2309-608X |