Toko K, Fujiyoshi T, Tanaka C, Iiyama S, Yoshida T, Hayashi K, Yamafuji K
Department of Electronics, Faculty of Engineering, Kyushu University 36, Fukuoka 812 Japan.
Biophys Chem. 1989 May;33(2):161-76. doi: 10.1016/0301-4622(89)80019-5.
A theory is presented for a relationship between ion accumulation and electric current loops in multicellular systems such as the roots and stems of higher plants. A network of electric circuits shows that the electric current transported across the cell membrane flows between an elongating region and a mature region, not only in roots but also in stems. In roots, ions constituting the extracellular electric current flow in the external aqueous medium, while in stems an electric current of comparable density flows within the epidermal cell wall. Based on this theoretical result, electric isolation between the elongating and mature regions was made in the case of both roots and stems. The speed of growth during the initial stage was greatly decreased due to a change in the distribution of protons around the surfaces of the plant by cutting off the electric current loop. Electrochemical calculation shows that ions are not always accumulated at the efflux site, since the ion distribution is strongly affected by the relation of the magnitudes between the electric field and electric current. The results calculated for the electric potential and pH distributions around the root agree with experimental data.
本文提出了一种关于多细胞系统（如高等植物的根和茎）中离子积累与电流回路之间关系的理论。一个电路网络表明，跨细胞膜传输的电流不仅在根中，也在茎中，在伸长区和成熟区之间流动。在根中，构成细胞外电流的离子在外部水介质中流动，而在茎中，密度相当的电流在表皮细胞壁内流动。基于这一理论结果，在根和茎的情况下都实现了伸长区和成熟区之间的电隔离。通过切断电流回路，植物表面质子分布发生变化，导致初始阶段的生长速度大幅下降。电化学计算表明，离子并不总是在流出部位积累，因为离子分布受到电场和电流大小关系的强烈影响。计算得出的根周围电势和pH分布结果与实验数据相符。
