Microtubule regulation during secondary cell wall formation

PhD defence by Beyza Özmen

Assessment Committee

Professor Alexander Schulz, PLEN, University of Copenhagen (Chairperson)
Professor Katharina Burstenbinder, University of Halle
Professor Esben Lorentzen, University of Aarhus

Supervisors

Professor Staffan Persson
Postdoc Shuai Zheng

Department

Department of Plant and Environmental Sciences

Place

Building: Main Building (Hovedbygningen), Building 1-01, Room: A1-01.01 Festauditoriet, Bülowsvej 17, 1870 Frederiksberg C

Email address to gain access to the thesis: bo@plen.ku.dk.
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Short description of the thesis

How do plant cells know exactly where to build structural reinforcements? Vascular plants rely on xylem tracheary elements with precisely patterned secondary cell walls (SCWs) for water transport and mechanical support. These SCW bands are templated by cortical microtubule (cMT) arrays, and while the transcriptional program initiating this process, driven by regulators like VND7, is well characterized, how cMT band geometry is refined afterward remains poorly understood.

Using an inducible VND7 system to trigger synchronous SCW formation and a proximity labeling approach (PUP-IT) to map the microtubule-proximal proteome in Arabidopsis, this thesis identifies KINL7, a previously uncharacterized kinesin-like protein, as a context-dependent regulator of cMT band coherence. KINL7 fine-tunes array geometry, likely through motility-dependent bundling regulated by autoinhibitory tail domains, revealing a new layer of cytoskeletal quality control in cell wall patterning.