Roots for the Future - A systematic approach to root design [SUREROOT]

The increasing frequency of extreme climate events in the UK suggests the approach of the 'Perfect Storm' described by Beddington (2009). In 2012 an early season drought followed by extreme rainfall and flooding over extensive areas of the UK drove the need for the 'climate smart' agriculture that will be used here to address the dual challenges of climate change and food security. Over an 80h period in November 2012, more than 46 x 106L of rain fell on the North Wyke Farm Platform (NWFP), 90% of which was immediately lost as overland flow or in drainage. Droughts also challenge the sustainability of UK grasslands and occur increasingly in winter where the warmer temperatures now encountered encourage continued winter growth placing drought susceptible varieties at risk. UK grasslands occupy 65% of all available agricultural land and unlike most other crops comprise perennial species that provide crop yields over many years. The combination of their extensive land-cover and persistency provides grasslands opportunities for environmental service in addition to their traditional roles as high quality forage for livestock agriculture. This is achieved through selection of the appropriate varieties and when necessary their modification, and improved grassland management, with benefits likely to persist over years. Grasslands provide catchments for many UK rivers and act as regulators of water capture, its release, and quality dependent on their composition.

IBERS is widely recognised for innovative approaches to breeding grass and clover varieties. However, variety development has untill now neglected programmes to improve root design or the opportunities for improved root-soil interactions that will deliver improved soil structure, hydrology, nutrient use and reduce the compaction that compromises crop yields. A recent BBSRC study published in Nature Scientific Reports (involving the PI of this proposal) demonstrated the potential for a novel grass species hybrid to initiate significant root-soil interactions that would if reproduced at the field-scale generate significant benefits in terms of flood control (DOI:10.1038/srep01683). Equivalent results have been recorded in white clover. In the current project, the potential of both for flood control will be assessed at the field scale, independently and as mixtures. The project will use two new BBSRC-supported National Capabilities: the National Plant Phenomics Centre (NPPC) and the North Wyke Farm Platform (NWFP). The project will investigate at different scales from the individual plant genotype, to the plot, through to the crop the potential for environmental service that may be achieved through a modified root design or growth pattern. The results achieved from the NPCC and NWFP facilities will be validated by testing selected varieties on commercial farms in diverse locations and under alternative livestock management systems.

The proposal will use the latest BBSRC high-throughput phenomic and genomic technologies, with a suite of well characterised and relevant experimental populations together with molecular markers to engage in marker-assisted breeding for improved root designs in elite forage grass and clover varieties. Plant materials suitable for entry into National List trials will be developed within the time-course of the project. This proposal is being submitted through the BBSRC stand-alone LINK scheme. The project will benefit from the involvement of industrial partners that represent the various sectors of the UK grassland and livestock industry allowing for identification and review of key targets, and evaluation of the impact of the research, dissemination of the results within the grassland sector, and uptake and delivery of project outcomes.

Climate-smart responses are required to mitigate effects of extreme weather events like flooding and these require precision technologies and their wide-spread adoption in order to achieve any significant success. Grasslands inhabit major land areas of the UK and are located appropriately in areas of high rainfall often acting as river catchments. We will employ 2 BBSRC National Capability Centres; IBERS National Plant Phenomics Centre and North Wyke Farm Platform. Precision phenotyping will provide plants of grass or clover having alternative root structure and ontogeny and these will be assessed for their impacts on soil structure. Where necessary, roots will be modified by inclusion of new genetic variants through plant hybridisation involving targeted gene introgression using a functional genetic marker-assisted breeding approach. Genotypes selected for their desirable root traits will be multiplied and populations and varieties tested at the plot and at the field scale. This will be undertaken at North Wyke where movements of water, nutrients and C will be monitored and assessments made in terms of benefits accrued through enhanced plant-soil interactions that limit flows of water and nutrients. To validate outcomes, real-farm assessments will be undertaken by industry partners in fields of grass and clover grown as monocultures or as mixtures, replicated over 8 Commercial Development farms distributed across the UK and using alterantive livestock management. Significant phenotype variation for root-based traits has been found and this will be extended further by hybridisation and gene transfers from related species. Their impacts on soils structure and hydrology will be measured and their genetic basis determined. From known QTL locations, relevant genetic sequences and SNPs will be identified that confer either deep rooting, water-use-efficiency, or root strength, and these will be transferred by MAS into elite varieties for entry and assessment in NL trials

The major beneficiaries of this research will be:
Plant breeding community: The project rectifies previous ommissions where forage ryegrass and clover breeding has largely neglected selections for improved root design and never involved their interactions with soils and impacts on soil structure, porosity and hydrology. Pilot studies have shown significant phenotypic variation for root structure and ontogeny between varieties and this will be extended further in hybrids. Information on the genetic control of root architecture and ontogeny and genomically and phenomically characterised germplasm will be available for trait dissection and breeding. Development of high throughput cost-effective phenotyping techniques linked to development of functional gene markers will provide "breeders toolkits" for root strength, depth, drought resistance and water-use-efficiency and allow precise marker-assisted trait selection for root traits over generations in forage plant breeding programmes. Breeders of related crop species that share genome synteny with ryegrass and clover will benefit through opportunities to identify orthologous gene loci in their crops.

Livestock sector: This work will have a significant economic and environmental impact on livestock production. Advanced germplasm will be developed into potential new ryegrass and clover varieties that will have improved root traits and will deliver environmental benefits to sustainable livestock production systems without compromising on agronomic performance. Indeed improved and more stress-resilient root systems should enhance the efficiency of crop production and mitigate costly losses of essential soil resources. The outputs of this project, to modify the root traits of grasses and clovers and reduce the impacts of excessive water (flooding) or sub-optimal water supply (drought) on the key species employed in UK grassland systems, are targeted and relevant to the whole of the grassland sector safeguarding supplies of fodder to livestock at times of extreme weather events. Both droughts, floods, and their interactions with soils that cause soil compaction either by livestock or farm machinery reduce crop yields significantly and compromise on persistency e.g. a reduced yield of ryegrass of 1t DM/ha for every 50mm of soil-water-deficit. Reduced leaching and run-off of soil nutrients following heavy rainfall should decrease through improved soil hydrology and lower requirements for additions of suppementary fertiliser.

Society: Improving the potential of grassland systems to act as front-line defences against flooding is a key objective of this project. In the UK, the cost of dealing with flooding runs into billions of pounds, e.g. it has been estimated that the devastating floods of summer 2007 cost £3.2b (Environment Agency). Excessive run-off erodes top soils and soil organic matter, and depletes valuable nutrients (N and P), with negative impacts on water quality. Eutrophication of surface and ground-waters in England and Wales is estimated to cost £75-114m/y due to loss of amenity value, reduced biodiversity and increased costs of water treatment. The damage to agricultural soil in England and Wales, and water treatment for pollution, have been estimated at nearly £500 x 106y-1 (UK Parliamentary Office of Science and Technology 2006). The cost of damage to agricultural soil in England and Wales has been estimated as £264m/yr, and that of treating water contaminated with agricultural pollutants as £203 million a year (UK Parliamentary Office of Science and Technology 2006). Perennial ryegrass is the grass of choice in UK livestock agriculture and the most widely sown. Pilot studies have indicated that rainfall run-off measured over a perennial ryegrass sward may be reduced by 51% should an alternative grass variety with a root system that induced a better soil porosity be used in its place. Clover roots induce similar benefits and may further enhance soil hydrology.