16 ERA-CAPS. MURINAS_Mechano-purino signalling in abiotic stress

To survive, plants must maintain an upright stem in the face of wind, while their roots must forage for water and nutrients despite soil hardness and compaction. Wind induces adaptive structural changes in stems, including tissue thickening. Roots penetrate hard substrate and modify their growth and shape as obstacles are sensed. Despite this adaptive capacity, mechanical stresses account for approximately 10% of annual European crop yield loss from wind lodging and 10-50% yield loss can arise from soil compaction. Discovering how plants sense and respond to mechanical stress could help in breeding better adapted crops. A protein has been identified in the model plant Arabidopsis thaliana that could sense mechanical stress in the plant cell wall and send a message to the cell to adapt. This protein (DORN1) sends its message by activating the movement of calcium into the cell and the increase of calcium acts as the signal to adapt. The objective of this project is to identify the proteins that enable calcium entry into the cell downstream of DORN1. The results obtained in Arabidopsis could be transferred to crops in the medium to long term. This innovation in understanding how these walled organisms cope with the mechanical stresses they face will provide a platform to improve crop lodging and root growth in line with trans-national strategic aims for agriculture.

Evidence is accumulating that points to intersects between mechanobiology [PNAS USA 110: 755] and purino-signalling [Science 343: 290] in plants. Purino-signalling is the transduction of signals elicited by extracellular purine nucleotides, such as ATP. Research on plant purino-signalling is gathering pace; extracellular ATP (eATP) has been found to increase as cells expand (a process that generates intrinsic mechanical stress) and eATP also increases in response to extrinsic mechanical stress. Moreover, eATP affects root development and governs the transcriptional response to wounding as the most severe mechanical stress. The recent discovery of the first plant purino receptor, Arabidopsis DORN1, provides a unique opportunity to explore at the molecular and whole plant levels the relationships between purino- and mechano-signalling. Critically, the structure of DORN1 indicates its acting as a reporter of cell wall state. In this ERA-CAPS consortium, two cross-discipline purino-signalling groups and a mechanobiology group will delineate the DORN1 mechano-purino signalling system using molecular, biochemical and biophysical approaches. The BBSRC-funded component will address the discovery of the cell membrane calcium channels mediating the DORN1-dependent calcium increase in roots and stems, using patch clamp electrophysiology.

Project impact lies in the development of sustainable agricultural production in the face of climatic change. Mechanical stresses account for approximately 10% of annual European crop yield loss from wind lodging, this may well rise as climate change brings increasingly stormy, erratic weather. Up to 50% of yield can be lost from soil compaction, whilst increasing drought events will impose both water stress and greater mechanical stress on roots. Better adapted crop plants are needed urgently but there is a paucity of information on withstanding mechanical stress. The consortium's work will identify new components of stem and root mechano-responses to wind and soil hardness respectively. These results have the potential to feed into wheat improvement programmes for lodging, wind resistance and penetrative root growth. In addition to aiding water and nutrient uptake, deeper roots with greater lateral outgrowth improve soil structure (improving water and nutrient retention) and may make a significant contribution to CO2 sequestration. Improved root growth by expression of a single gene has been shown to improve crop yield by 60%, demonstrating the potential of identifying and exploiting new components. Wind damage also inflicts losses on forestry and urban landscapes, so increasing our understanding of the molecular basis of wind sensing and adaptation can be relevant to those sectors. in addition to dissemination of results through conferences and research publications, forging links to industry through the Cambridge Translational Research Group will help ensure impact. Thus, this project will provide foundation elements for understanding the adaptability of plants to stress in this current context of climate change and for improving crop yield for the increasing global population. This fundamental research will have significant and diverse impacts on research communities, from there the food and forestry industries, and hence economies and society.