Handling Editor: Derek Walsh
ABSTRACT
The fungus Magnaporthe oryzae uses a specialized pressure-generating infection cell called an appressorium to break into rice leaves and initiate disease. Appressorium functionality is dependent on the formation of a cortical septin ring during its morphogenesis, but precisely how this structure assembles is unclear. Here, we show that F-actin rings are recruited to the circumference of incipient septin disc-like structures in a pressure-dependent manner, and that this is necessary for their contraction and remodeling into rings. We demonstrate that the structural integrity of these incipient septin discs requires both an intact F-actin and microtubule cytoskeleton and provide fundamental new insight into their functional organization within the appressorium. Lastly, using proximity-dependent labeling, we identify the actin modulator coronin as a septin-proximal protein and show that F-actin-mediated septin disc-to-ring remodeling is perturbed in the genetic absence of coronin. Taken together, our findings provide new insight into the dynamic remodeling of infection-specific higher-order septin structures in a globally significant fungal plant pathogen.
Footnotes
Competing interests
The authors declare no competing or financial interests.
Author contributions
Conceptualization: M.J.E.; Methodology: R.L., Y.W., M.J.E.; Formal analysis: N.D., R.L., V.R.K., Y.W., M.J.E.; Investigation: N.D., A.M.R., R.P., B.D.B., R.L.; Writing - original draft: R.L., Y.W., M.J.E.; Visualization: M.J.E.; Supervision: Y.W., M.J.E.; Project administration: A.M.R., M.J.E.; Funding acquisition: Y.W., M.J.E.
Funding
This work was funded by a University of Arkansas Chancellor's Innovation and Collaboration Fund award to M.J.E. and Y.W.
Supplementary information
Supplementary information available online at https://jcs.biologists.org/lookup/doi/10.1242/jcs.251298.supplemental
- Received July 10, 2020.
- Accepted December 16, 2020.
- © 2021. Published by The Company of Biologists Ltd
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