植物凯氏带形成分子机制及功能特点的研究进展

凯氏带位于被子植物初生根内皮层细胞,环绕细胞1周,是与质膜紧密结合的非极性带状增厚结构。凯氏带作为植物根中离子径向运输障碍,调节离子的质外体吸收途径,迫使土壤中的离子通过内皮层细胞膜,选择性地进入中柱。凯氏带发现于1865年,但直至拟南芥凯氏带蛋白的发现和凯氏带阻滞作用物质基础被揭示,凯氏带的形成机理和功能才逐渐为人们所认知。凯氏带的物质基础为木质素,其形成需要由凯氏带蛋白和受体激酶组成的合成平台。细胞内部的木质素单体经ABCG载体运输到凯氏带的形成区,经ESB1dirigent蛋白、RBOHF氧化酶和PER64过氧化物酶等催化,合成木质素。该文对近年来国内外有关凯氏带形成的分子机制和功能特点方面的研究进展进行综述,为进一步理解和解析凯氏带的形成机理和功能提供参考。

Molecular Mechanism of Formation and Functional Characteristics of Casparian Strip

Casparian strips are a cellular feature found in the roots of all higher plants, which are ring like, hydrophobic cell wall impregnations that tightly attach with the endodermal cell membrane. Casparian strip acts as a barrier to the free diffusion of solutes from the soil, and forces ions through endodermal cell into the stele. Casparian strip was found in 1865, but many botany textbooks cannot give completely correct information on it. The mechanism of its formation was gradually aware until Casparian strip membrane domain proteins (CASPs) were characterized and the substance of Casparian strip were revealed. The scaffold, which consists of CASPs and receptor like kinases, was needed for Casparian strip formation. Casparian strip diffusion barrier in Arabidopsis is made of a lignin, and NADPH oxidase RBOHF, Peroxidase Per64 and ESB1 dirigent protein were used to catalyze the polymerization with monolignol, which was transported from cell into Casparian strip membrane domain by ABCG transporter. Here, we reviewed the major findings and models related to Casparian strip and its function in light of recent molecular data. This article can provide a framework and inspiration for further molecular dissection.