Discovering How Root Sense Hard Soils

土壤压实是现代农业面临的主要挑战。如果再加上干旱等其他压力，土壤压实会使作物减产高达75%，每年造成数十亿欧元的损失。开创性的项目解决了植物根系如何感知不同程度的土壤压实并改变其生长。该项目建立在我最近的发现基础上，即根系对高度土壤压实的反应是由气体信号“乙烯”控制的（Pandey等人，2021年，Science，Huang等人，2022年，PNAS）。然而，农业土壤的硬度差别很大。欧洲除了3600万公顷高度压实的土壤外，还有2500万公顷易于中等压实的土壤。因此，发现哪些信号通路控制根系对低到中等、高到非常高水平土壤压实的感知，对于培育更具气候适应性的作物至关重要。我假设根系利用新的挥发性信号来感知中等水平的土壤压实，并利用机械信号途径来感知非常高水平的土壤压实。这种新型信号范式的前提是基于挥发性信号分子和土壤孔隙的大小，它们影响气体信号在压实土壤中扩散的能力。然而，当土壤孔径太小，甚至不能让气体交换像乙烯这样的小信号时，机械信号将接管控制高度密实土壤中的根系反应。开创性的项目将开拓我最近确定的控制根压实反应的新型挥发性和机械信号通路的特征，揭示其潜在的分子，细胞和组织尺度机制，然后为根-土壤信号传递创造一个新的范例。为了实现这些雄心勃勃的目标，我将整合跨学科的土壤物理专业知识，最先进的非侵入性成像，前沿分子生物学和自然土壤条件下的遗传方法。这个开创性的项目也非常及时，因为关于压实反应的新知识将为设计作物根系的努力提供基础，使其长深，并获得更可靠的水资源。

Soil compaction represents a major challenge facing modern agriculture. When combined with other stresses like drought, soil compaction can reduce crop yields by up to 75% and causes billions of Euros in losses annually. The GROUNDBREAKING project addresses how plant roots sense different levels of soil compaction and modify their growth. This Project builds on my recent discovery that root responses to a high level of soil compaction are controlled by the gaseous signal "ethylene" (Pandey et al., 2021, Science,Huang et al., 2022, PNAS). However, agriculture soils vary greatly in terms of their hardness. Europe, inaddition to 36-million hectares of highly compacted soil, contains 25-million-hectares of soil prone to medium compaction. Therefore, discovering which signalling pathways control root sensing of low to medium and high to very high levels of soil compaction is vital for developing more climate resilient crops. I hypothesise that roots employ novel volatile signals to sense medium levels of soil compaction, and mechanical signalling pathways to sense very high level of soil compaction. The premise of this novel signalling paradigm is based on the size of volatile signalling molecules and soil pores that impact the ability of gaseous signals to diffuse through compacted soil. However, when soil pore size is too small to allowgaseous exchange for even small signals like ethylene, mechanical signalling will take over to control root responses in very highly compacted soil. The GROUNDBREAKING project will pioneer the characterisation of novel volatile and mechanical signalling pathways I have recently identified control root compaction responses, revealing their underlying molecular, cellular and tissue-scale mechanisms, then creating a new paradigm for root-soil signalling. To realise these ambitious goals, I will integrate interdisciplinary expertise in soil physics, state-of-the-art non-invasive imaging, cutting edge molecular biology and genetic approaches under natural soil conditions. The GROUNDBREAKING project is also very timely as the new knowledge generated about compactionresponses will underpin efforts to engineer crop roots to grow deeper and access more reliable water resources.