Plant root diffusional barriers: genesis and implications for nutrient efficiency and stress tolerance

Casparian条带和suberin分别通过在相邻细胞之间以及细胞壁和质膜之间提供紧密的密封来限制植物根中的细胞外扩散。这种扩散屏障是至关重要的，使根内胚层细胞层作为一个选择性屏障，允许控制吸收水和溶质进入植物。此外，这些屏障还被认为为病原体渗透到根部提供了化学或物理障碍，包括植物寄生线虫进入维管系统取食。驱动这些关键屏障生物合成的分子机制知之甚少，限制了我们充分表征其功能和操纵其特性以获得农业效益的能力。我们设计了一个雄心勃勃的跨学科研究计划，将分子植物科学与分析化学、全植物生理学和建模相结合。本课程旨在全面了解从分子到整个植物的各个尺度的卡斯帕里斯条带和木栓质的生物学。这些信息将使分子定向操作Casparian条带和木参素成为可能，为作物品种的开发提供新的途径，提高养分和水分利用效率，增强对根系病原体、盐度和水分胁迫的抵抗力。如果我们要开发出对气候变化对土壤肥力的预测影响更有弹性的作物，并以更可持续的方式提高产量，以实现满足未来人口增长所需的产量增长，这些性状是必不可少的。通过采用基因组学、分子遗传学、化学、生化和细胞生物学方法，我们将发现和表征参与卡斯帕里斯条和木栓素生物合成的基因和分子机制。通过这一机制研究鉴定和开发的遗传资源将有助于在根和全株水平上理解这些物理和化学屏障在矿质养分和水分吸收以及根寄生线虫感染中的作用。还将确定这些屏障的生态和适应功能，以应对与农业有关的非生物胁迫，如水、矿物质营养（缺乏和过量）和盐度。基于这一新的认识，将分子机制知识与组织和整个植物水平的生理过程相结合的数学模型也将建立起来，为将屏障特性与整个植物功能联系起来提供预测能力。

Casparian strips and suberin limit extracellular diffusion in plant roots by providing tight seals between adjacent cells, and between the cell wall and the plasma membrane, respectively. Such diffusional barriers are vital to enable the root endodermal cell layer to act as a selectivity barrier allowing controlled uptake of water and solutes into plants. Further, these barriers are also thought to provide a chemical or physical block to pathogen penetration into roots, including plant-parasitic nematodes accessing the vascular system for feeding. The molecular mechanisms that drive the biosynthesis of these critical barriers are poorly understood, limiting our ability to fully characterize their function and manipulate their properties for agricultural benefit. We have designed an ambitious interdisciplinary research programme integrating molecular plant science with analytical chemistry, whole plant physiology and modelling. This programme aims to deliver a complete understanding of the biology of Casparian strips and suberin, across scales, from molecules to the whole plant. Such information will enable a molecularly directed manipulation of Casparian strips and suberin, providing new pathways for the development of crop varieties with improved nutrient and water use efficiencies, and enhanced resistance to root pathogens, salinity and water stress. Such traits are essential if we are to develop crops that are more resilient to the predicted impacts of climate change on soil fertility, and to improve yields in a more sustainable manner to deliver the yield gains required to meet future population growth. By employing genomic, molecular genetic, chemical, biochemical and cell biological approaches we will discover and characterize the genes and molecular mechanisms involved in the biosynthesis of Casparian strips and suberin. Genetic resources characterized and developed through this mechanistic investigation will be leveraged to understand, at the root and whole plant level, the role of these physical and chemical barriers in mineral nutrient and water uptake, and root parasitic nematode infection. The ecological and adaptive function of these barriers to agriculturally relevant abiotic stresses such as water, mineral nutrient (deficiency and excess) and salinity will also be established. Building on this new understanding, mathematical models integrating molecular mechanistic knowledge with physiological processes at the tissue and whole plant level will also be built, providing predicative capacity to connect barrier properties with whole plant function.