ROOTS FOR THE FUTURE- A SYSTEMATIC APPROACH TO ROOT DESIGN (SUREROOT) (BBSRC-LINK)

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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 has never involved their interaction with soils with the impact these have on structure, porosity and hydrology. Pilot studies have shown significant phenotypic variation for root structure and ontogeny to exist 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 ctops.

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 which will have the improved root traits that will deliver environmental benefits to sustainable livestock production systems without compromising agronomic performance. Indeed improved and more stress resilient root systems should enhance the efficiency of crop production and mitigate losses of essential soil resources. The outputs of this project, to modify the root traits of grasses and legume and reduce the impact of excessive water (flooding) or sub-optimal water supply (drought) on key species of 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 lessen through improved soil hydrology to 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 through 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.