これまで、葉面散布や根からの吸収では、細胞壁や表皮が壁となり、植物に運べる粒子はナノサイズ（<40 nm）に限られていました。私たちは、トマト苗木の「茎を切って浸す」という単純な方法で、この限界を大きく超え、最大110 nmの粒子を植物内部まで届けることに成功しました。🍅🌱

Until now, particle delivery into plants via foliar spray or root uptake has been capped at roughly 40 nm — blocked by the cell wall and cuticle. We found a way past that ceiling: by simply cutting the stem of tomato seedlings and immersing them in a particle suspension, we delivered particles up to 110 nm — nearly three times the previous size limit — deep into the plant.

Plant Physiology and Biochemistry誌（欧州植物生物学会連合公式学術誌）に掲載。
Published in Plant Physiology and Biochemistry (official journal of the Federation of European Societies of Plant Biology).

What we did / 実験概要
水不溶性のシリカコロイド粒子（平均粒径10 nmおよび110 nm）を用意し、35日齢のトマト苗木の茎を切断、コロイド懸濁液（濃度10 mg/L）に最大24時間浸しました。
We used water-insoluble silica colloid particles (average diameters of 10 nm and 110 nm), cut the stems of 35-day-old tomato seedlings, and immersed them in a low-concentration suspension (10 mg/L) for up to 24 hours.

What we found / 結果
両サイズの粒子がともに茎を通って輸送され、節や葉に顕著に蓄積しました。さらに、粒子導入後も苗木は不定根を形成し、根・茎・葉を備えた健全な植物として成長を続けました。
Both particle sizes moved through the stem and accumulated significantly in the nodes and leaves. Remarkably, the seedlings continued to develop normally after particle uptake — forming adventitious roots and growing into complete, healthy plants with roots, stems, and leaves.

Why it matters / 意義
この「茎切り」法は、これまで不可能だったサブミクロンサイズの粒子導入を可能にし、トマトに限らず他の食用作物にも応用できる可能性があります。植物への機能性粒子導入という、農業・バイオテクノロジー分野の新しい選択肢を開くものです。
This stem-cutting method opens a delivery route that was previously closed to submicron particles — and it isn’t limited to tomatoes. It offers a new, broadly applicable strategy for introducing functional particles into food crops, with implications across agriculture and plant biotechnology.

Permanent link: https://doi.org/10.1016/j.plaphy.2023.108297
Author Final Version (PDF): https://researchmap.jp/wlenggoro/published_papers/44332868/attachment_file.pdf

Stem cutting: A novel introduction site for transporting water-insoluble particles into tomato (Solanum lycopersicum) seedlings 

Authors: Anca Awal Sembada, Toshiyuki Fukuhara, Takeshi Suzuki and I. Wuled Lenggoro

Chemical Engineering Program, Graduate School of Engineering, Tokyo University of Agriculture and Technology (TUAT)（農工大・応用化学専攻）; School of Life Sciences and Technology, Bandung Institute of Technology, Indonesia（バンドン工科大学・生命理工学院）; Department of Applied Biological Science, Graduate School of Agriculture, TUAT（応用生物科学科）; Graduate School of Bio-Applications & Systems Engineering, TUAT（生物システム応用科学府）; Department of Applied Physics and Chemical Engineering, Graduate School of Engineering, TUAT（化学物理工学科）