A receptor-like mechanosensitive protein governs preprophase band positioning for asymmetric cell divisions and SC morphogenesis

What is it about?

Asymmetric cell division constitutes the developmental cornerstone for generating cellular diversity. While plant cells uniquely position their division plane via microtubule preprophase band (PPB) alignment with mechanical stress patterns, the molecular translator converting wall stress into cytoskeletal instructions has remained unknown since PPB discovery in 1960. Resolving this mechanochemical code is essential for understanding morphogenesis across kingdoms. Here, we identified the maize receptor-like protein KAI1. KAI1 senses pectin-mediated cell wall stress in a force-dependent manner, recruits tubulin to position the PPB, and thereby steers the orientation of asymmetric cell division. Loss of KAI1 function accelerates water loss, disrupts stomatal morphology, and impaires stomatal conductance. A suite of mechanical stimulation and cell wall perturbation experiments confirms that KAI acts as a direct wall force sensor to reshape the cytoskeleton and determine cell division planes during grass stomata formation.

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Photo by Soubhagya Satpathy on Unsplash

Photo by Soubhagya Satpathy on Unsplash

Why is it important?

This study solves a 60-year puzzle: how plants molecularly regulate asymmetric cell division, ever since the PPB was first observed. It elucidates how mechanical signals guide asymmetric division and cell fate, and provides a mechanism for establishing asymmetrical cellular division and cell fate determination. Overall, this study constructs a complete regulatory module consisting of pectin, mechanical force, KAI1, and cytoskeleton, and establishes an innovative theoretical model for mechanical force-cytoskeleton crosstalk. It clearly illustrates how cell wall mechanical forces coordinate with cytoskeletal systems to determine division-plane orientation. These findings advance our understanding of how cell fate is determined, and provide key gene targets and a theoretical basis for engineering stomatal traits and breeding drought-resistant, high-yield grass crops.