The phosphatase gene MaCdc14 negatively regulates UV-B tolerance by mediating the transcription of melanin synthesis-related genes and contributes to conidiation in Metarhizium acridum.

Abstract

Reversible phosphorylation of proteins regulated by protein kinases and phosphatases mediate multiple biological events in eukaryotes. In this study, a dual-specificity cell division cycle 14 phosphatase, MaCdc14, was functionally characterized in Metarhizium acridum. Deletion of MaCdc14 decreased branch numbers, affected septum formation and resulted in multiple nuclei in each hyphal compartment, indicating nuclear division and cytokinesis defects. The spore production capacity was severely impaired with decreased conidial yield and delayed conidiation in MaCdc14-deletion mutant (ΔMaCdc14). The transcription levels of conidiation-related genes were significantly changed after MaCdc14 inactivation. The morphology of conidia was uneven in size and the germination rate of conidia was increased in ΔMaCdc14. In addition, ΔMaCdc14 displayed significantly enhanced conidial tolerance to ultraviolet (UV) irradiation but had no significant effect on the thermotolerance, the sensitivities to cell wall damage reagents, osmotic and oxidative stresses, and virulence compared to the wild-type strain and complementary transformant. Furthermore, the pigmentation of ΔMaCdc14 was increased by the upregulated expression of melanin synthesis-related genes, which may result in the enhanced UV-B tolerance of ΔMaCdc14. In summary, MaCdc14 negatively regulated UV-B tolerance by mediating the transcription of melanin synthesis-related genes, contributed to conidiation by regulating the expression levels of conidiation-related genes and also played important roles in cytokinesis and morphogenesis in Metarhizium acridum.