The Casparian strip (CS) is a tight junction-like structure formed by lignin impregnation on the walls of endodermal cells in plant roots. The CS membrane domain (CSD^M), demarked by the CASP proteins, is important for orienting lignification enzymes. Here, we report that an endodermis-expressed multicopper oxidase, LACCASE3 (LAC3) in Arabidopsis, locates to the interface between lignin domains and the cell wall during early CS development prior to CASP1 localizing to CSD^M and eventually flanks the mature CS. Pharmacological perturbation of LAC3 causes dispersed localization of CASP1 and compensatory ectopic lignification. These results support the existence of a LAC3-based CS wall domain which coordinates with CSD^M to provide bidirectional positional information that guides precise CS lignification.

里海带（CS）是一种紧密连接的结构，通过木质素浸渍在植物根部的内胚层细胞壁上形成。由CASP蛋白标记的CS膜结构域（CSD ^M）对于定向木质化酶很重要。在这里，我们报告说，在拟南芥中，在CASP1定位到CSD ^M之前，CS早期发育期间，木质素表达的多铜氧化酶LACCASE3（LAC3）位于木质素结构域和细胞壁之间的界面，最终定位在成熟的CS两侧。LAC3的药理扰动会导致CASP1的分散定位和代偿性异位木质化。这些结果支持了与CSD ^M协调的基于LAC3的CS壁域的存在。 提供指导精确CS木质化的双向位置信息。