Suberin plasticity to developmental and exogenous cues is regulated by a set of MYB transcription factors

背景回顾：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. 

提出问题：However, the mechanisms controlling its spatiotemporal regulation are poorly understood.

主要发现：Here, we show that endodermal suberin is regulated independently by developmental and exogenous signals to fine-tune suberin deposition in roots.

结果1-4个MYBs：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. 

结果2-功能缺失突变：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. 

结果3-木栓质与凯氏带：Most suberin mutants analyzed at physiological levels are also affected in another endodermal barrier made of lignin (Casparian strips) through a compensatory mechanism. 

结果4-单独研究木栓质：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.

 摘 要 

木栓质是一种疏水性生物聚合物，可以沉积在细胞的边缘，形成一层保护屏障，抵抗生物和非生物胁迫。在根中，木栓质在内皮层细胞的边缘形成片层，在控制水分和矿物质运输中起着关键作用。木栓质的形成受到发育和外界环境的强烈调控。然而，控制木栓质形成的时空调控的机制尚不清楚。本文中，作者发现，内皮层木栓质受到发育和外源信号的独立调节，从而精细调控木栓质在根中的沉积。作者鉴定了一组MYB转录因子，即MYB41、MYB53、MYB92和MYB93，其中每一个转录因子都会受这两种信号的单独调节，并且足以促进内皮层木栓质的形成。通过基因组编辑技术，作者构建了四突株系，发现其响应发育和环境信号的木栓质形成明显减少。大多数的木栓质突变体通过补偿机制，另一个由木质素形成的内皮层屏障，即凯氏带也会被影响。通过对这四个MYBs的功能分析，作者获得了能够对内皮层木栓质功能进行无偏研究的材料，而无需考虑由凯氏带缺陷所引起的混杂效应，并且能够揭示木栓质在营养稳态中的特定作用。