New Article: "A cytokinin response maximum induces and activates bifacial stem cells for radial growth" rdcu.be/eBbtc

Initiation of radial growth, during which a transient cytokinin response maximum transforms dormant procambial cells into bifacial stem cells.

Free-to-read version here👇 rdcu.be/ey7yj

9/9
Huge thanks to all collaborators! Special thanks to Prof. Hidehiro Fukaki (Kobe Univ.) — his lab's imaging setup was essential. And to Dr. Takaaki Yonekura @monera-kingdom.bsky.social, a former senior whose modeling directly supported our conclusions.

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This work is the culmination of 7.5 years of research, starting from my undergraduate days.
Deep thanks to my supervisor Prof. Yuki Kondo @ykondolab.bsky.social for unwavering support.

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This means:
💡 Cytokinin is not just a generic growth signal —
It’s a switch that creates stem cells specifically for radial growth.

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So what does cytokinin actually do during this peak?
It induces and activates stem cells.
Before the CRM, cells can’t directly differentiate to xylem or self-renew. After the CRM, they gain both abilities.

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In Arabidopsis roots, cytokinin response imaging revealed something surprising:
A clear but transient peak of cytokinin signaling — which we called the cytokinin response maximum (CRM) — appears.
2–3 days later, radial growth begins.

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Using a vascular cell induction system called VISUAL, combined with single-cell transcriptomics and luminescence imaging, we found something else:
Cytokinin doesn't just boost division — it promotes the transition of dormant procambial cells into active cambial stem cells.

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Cytokinin was already known to be important for radial growth, but mostly thought to just promote cell division.
We questioned this assumption.

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In many plants like trees, bifacial cambial stem cells drive radial growth by dividing actively.
Before that, they exist as inactive procambial cells — waiting in a dormant state.

1/n
What triggers plants to start growing thicker (radial growth)?
We discovered that a transient cytokinin response maximum acts as a switch to initiate this process in roots.
So proud to share the work I started as an undergrad, now in Nature Plants! 🧵👇
www.nature.com/articles/s41...

Our review article on primary vascular development in Arabidopsis has been published.

Coordination and regulation of vascular development in roots
www.sciencedirect.com/science/arti...

Kondo Lab has started Bluesky.

In our latest work, we provide molecular insights into the age-dependent morphological changes occurring in the root meristem during phase change. Perseverance over many years by BaoJun Yang and Yanbiao Sun. Generous funding by ERC, FWO, VIB and UGent #plantscience
www.science.org/doi/10.1126/...

Finally out! We identified the stem cell factors (CAILs) of the vascular cambium, and a mechanism involving a ligand sequestration to position the stem cells. This work is a result of fruitful collaboration with @peteretchells.bsky.social and Tusscher labs. 🧵 1/x
www.science.org/doi/10.1126/...