Recent decades have seen a dramatic increase in research on plant roots. A deeper understanding of the complex ways roots interact with soils is making it possible to 'design' roots to optimise nutrient/water uptake in low-input environments as well as deliver other benefits such as improved soil health and reduced nutrient leaching. This collection summarises the wealth of current research in this important area and how it can contribute to more sustainable, 'climate-smart' crop production. Part 1 in this collection reviews recent research on understanding root system architecture and growth together key interactions in the rhizosphere. Chapters cover topics such as measurement and modelling techniques, root architecture, root growth regulators, root anatomy and nutrient acquisition. Part 2 assesses how roots respond to biotic stresses such as parasites, pathogens nematodes. Part 3 summarises what we know about root uptake of water and key nutrients such as nitrogen and, phosphorus Part 4 explores how this understanding can be used to optimise root function.