MaPmt1, a protein O-mannosyltransferase, contributes to virulence through governing the appressorium turgor pressure in Metarhizium acridum

• Published in: Fungal genetics and biology 2020-12, Vol.145, p.103480-103480, Article 103480
• Main Authors: Wen, Zhiqiong, Tian, Huiting, Xia, Yuxian, Jin, Kai
• Format: Article
• Language: English
• Subjects: Appressorium turgor pressure; Cell wall integrity; MaPmt1; Metarhizium acridum; O-mannosyltransferase; Virulence
• ISSN: 1087-1845; 1096-0937
• DOI: 10.1016/j.fgb.2020.103480

[Display omitted] •An ortholog of Pmt1 was functionally characterized in Metarhizum acridum.•MaPmt1 contributed to fungal virulence.•Deletion of MaPmt1 had no effect on appressorium formation but specifically declined the turgor pressure of appressorium.•Deletion of MaPmt1 affected the fungal cell wall integrity and content of intercellular glycerol. O-glycosylation is a very important post-translational modification of protein and involved in many cell processes in fungi. There exist three protein O-manosyltransferanse genes (MaPmt1, MaPmt2, MaPmt4) in Metarhizium acridum based on sequence homology. Here, MaPmt1, a gene for Pmt1 O-manosyltransferanse in M. acridum, was characterized and functionally analyzed through targeted gene disruption and complementation methods. Deletion of MaPmt1 had no effect on conidial germination, but slightly increased the conidial yield and significantly impaired fungal tolerances to UV-B radiation and wet-heat. Deletion of MaPmt1 made the fungus become more sensitive to cell wall disturbing agents and exhibit a thinner cell wall with changed components. Insect bioassays showed that disruption of MaPmt1 attenuated the fungal virulence significantly by topical inoculation but not by injection, indicating that MaPmt1 is required for penetration during the infection of M. acridum. Interestingly, deletion of MaPmt1 did not affect appressorium formation but significantly decreased appressorium turgor pressure. Moreover, the decreased virulence of MaPmt1 disruptant is mainly due to the reduced appressorium turgor pressure, which may be resulted from the declined glycerol concentration, combined with the weakened cell wall that could not hold the normal appressorium turgor pressure to penetrate the host cuticle.