作物改良の主要メカニズムを解明(Key Mechanism on Crop Improvement Unlocked)

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2025-12-09 中国科学院(CAS)

中国科学院の研究チームは、植物の幹細胞が新たな葉・茎・花を生み続ける仕組みを制御する「細胞壁の力学的性質」が、作物改良に直結する重要メカニズムであることを解明した。研究では、茎頂分裂組織などの幹細胞領域で、細胞壁主成分ペクチンが成熟壁では硬く、新生壁では柔らかいという二峰性パターンを示すことを発見。特に、新生壁を柔らかくする酵素 PME5 が、mRNA を核内に隔離しておき、細胞分裂時に核が一時的に崩壊する瞬間にのみ放出・翻訳され、形成中の壁へ正確に送られる仕組みを明らかにした。この巧妙な“核内封印”による局所的な壁軟化は、細胞配列や器官形成の精密制御を可能にし、穀粒の大型化、分げつ数増加、果実の肥大など理想的な作物形態の設計につながると期待される。結果は Science 掲載で、世界的な食料生産向上への理論的基盤を提示している。

<関連情報>

細胞壁のパターン形成は植物幹細胞の動態を制御する Cell wall patterning regulates plant stem cell dynamics

Xianmiao Zhu, Xing Chen, Yangxuan Liu, Yimin Zhu, […] , and Weibing Yang
Science  Published:4 Dec 2025
DOI:https://doi.org/10.1126/science.ady4102

Editor’s summary

Plant cells are wrapped in a semirigid wall that reconfigures as cells expand. The chemical and material properties of pectin, a key component of cell walls, can influence cell division. Zhu et al. found different pectin properties in new versus mature cell walls, which are controlled by pectin-modifying enzymes such as PME5. The authors established that PME5 RNA is sequestered in the nucleus by RNA-binding proteins. The PME5 messenger RNA (mRNA) is released into the cytoplasm during cytokinesis when the nuclear envelope breaks down. By spatially controlling PME5 mRNA, modification of pectin can be precisely timed to coincide with the formation of new cell division plates. —Madeleine Seale

Abstract

The plant cell wall regulates development through spatiotemporal modulation of its chemical and mechanical properties. Pectin methylesterification is recognized as a rheological switch controlling wall stiffness. Here, we reveal a bimodal methylesterification pattern in the shoot meristem: Mature walls exhibit high methylesterification, whereas demethylesterified pectins are deposited at new cross walls. This spatial heterogeneity is established through nuclear sequestration of PECTIN METHYLESTERASE5 (PME5) mRNA. MYB3R4-driven transcription, combined with RZ-1B/1C-mediated retention, creates a mitotically associated PME5 mRNA reservoir in the nucleus. Nuclear envelope disassembly synchronizes PME5 messenger RNA (mRNA) release with cell plate formation, enabling precise demethylesterification at division planes. Perturbation of this spatial control compromises stem cell maintenance or breaks division patterning. Our study uncovers an mRNA compartmentalization mechanism that couples stem cell dynamics with pectin modification.

細胞遺伝子工学
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