Suberin is a hydrophobic biopolymer that can be deposited at the periphery of cells, forming protective barriers against biotic and abiotic stress. In roots, suberin forms lamellae at the periphery of endodermal cells where it plays crucial roles in the control of water and mineral transport. Suberin formation is highly regulated by developmental and environmental cues. However, the mechanisms controlling its spatiotemporal regulation are poorly understood. Here, we show that endodermal suberin is regulated independently by developmental and exogenous signals to fine-tune suberin deposition in roots. We found a set of four MYB transcription factors (MYB41, MYB53, MYB92, and MYB93), each of which is individually regulated by these two signals and is sufficient to promote endodermal suberin. Mutation of these four transcription factors simultaneously through genome editing leads to a dramatic reduction in suberin formation in response to both developmental and environmental signals. Most suberin mutants analyzed at physiological levels are also affected in another endodermal barrier made of lignin (Casparian strips) through a compensatory mechanism. Through the functional analysis of these four MYBs, we generated plants allowing unbiased investigation of endodermal suberin function, without accounting for confounding effects due to Casparian strip defects, and were able to unravel specific roles of suberin in nutrient homeostasis.

Suberin 是一种疏水性生物聚合物，可沉积在细胞外围，形成针对生物和非生物胁迫的保护屏障。在根中，木栓质在内胚层细胞的外围形成薄片，它在控制水和矿物质运输中起着至关重要的作用。Suberin 的形成受发育和环境因素的高度调节。然而，对其时空调节的控制机制知之甚少。在这里，我们表明内胚层木栓质由发育和外源信号独立调节，以微调根中的木栓质沉积。我们发现了一组四个 MYB 转录因子（MYB41、MYB53、MYB92 和 MYB93），每一个都受这两个信号的单独调节，足以促进内胚层木栓质。通过基因组编辑同时突变这四种转录因子导致响应发育和环境信号的木栓质形成显着减少。在生理水平上分析的大多数木栓质突变体也通过补偿机制在由木质素（Casparian 条）制成的另一个内胚层屏障中受到影响。通过对这四种 MYB 的功能分析，我们生成了允许对内胚层木栓质功能进行公正研究的植物，而不考虑由于里海带缺陷造成的混杂效应，并且能够阐明木栓质在营养稳态中的特定作用。在生理水平上分析的大多数木栓质突变体也通过补偿机制在由木质素（Casparian 条）制成的另一个内胚层屏障中受到影响。通过对这四种 MYB 的功能分析，我们生成了允许对内胚层木栓质功能进行公正研究的植物，而不考虑由于里海带缺陷造成的混杂效应，并且能够阐明木栓质在营养稳态中的特定作用。在生理水平上分析的大多数木栓质突变体也通过补偿机制在由木质素（Casparian 条）制成的另一个内胚层屏障中受到影响。通过对这四种 MYB 的功能分析，我们生成了允许对内胚层木栓质功能进行公正研究的植物，而不考虑由于里海带缺陷造成的混杂效应，并且能够阐明木栓质在营养稳态中的特定作用。