IWYP Call 2: Rooty-A root ideotype toolbox to support improved wheat yields

This project assembles a world-class team of leaders in root research and wheat genetic improvement from seven institutes and five breeding companies, and brings this expertise into the IWYP programme. Our goal of optimising root systems is a critical component of the overarching IWYP aim of raising yield potential: higher yielding crops developed through IWYP will most likely demand more water and nutrients to support those yields, and roots must supply these in an efficient manner without draining any more carbon away from grain formation than is necessary to provide this function. The project builds on state-of-the-art developments in wheat genomic tools, germplasm resources, 'Speed Breeding', physiological and genetic understanding of root growth/development, high-throughput root phenotyping methods and the creation of novel genetic variation ready for exploitation. We establish a pipeline to validate the impact of root ideotype on yield, based on the use of: (1) recently cloned genes, (2) known QTL, and (3) de novo natural and artificial allele discovery. This pipeline provides staggered delivery of validated root ideotypes that will feed the breeding activities carried out by the IWYP Hub, participating breeding companies, and wider wheat breeding networks. By focusing on the often ignored 'invisible half' of the crop, this approach complements IWYP work on above ground traits, ultimately providing the knowledge and resources to allow above and below ground approaches to be combined in the future to maximise yield genetic gains.

Rooty is a multidisciplinary project with 6 workpackages:

WP1-Fast track stacking of cloned root angle gene and known QTLs into elite CIMMYT, EU and Australian wheat germplasm
WP2-Exploiting novel genetic variation for beneficial root phenotypes via TILLING
WP3-Genome editing to create novel variation for deep, narrow root systems
WP4-Genetic characterisation of novel root architecture genes
WP5-Testing yield x root trait interactions using lines with high yield potential
WP6-Field validation of root phenotypes and yield

The project will establish a pipeline of materials and knowledge that allow root architecture alleles/allelic combinations to be precisely assessed for root architecture and its impact on yield in elite genetic backgrounds adapted to three broad wheat growing regions: countries within CIMMYT's remit; Australia; NW Europe (focussed on winter wheat). The research pipeline (WPs 1 to 5), serving the validation phase (WP6), is organised into four overarching Tiers, providing a framework for continued research and translation post-project:

Tier 1-Cloned wheat root genes and well-characterised QTL.
Tier 2-Characterisation of novel alleles: artificial variants. Includes allele discovery/creation via TILLING and genome editing.
Tier 3-Characterisation of novel alleles: natural variants. Allele discovery via forward genetic screens of mapping populations created from genetically diverse wheat germplasm.
Tier 4-Forward scanning for sources of novel root architecture alleles/phenotypic diversity.

Work is predominantly focused on near-term validation (Tier 1), but reflects the increasing timescales of mid- (Tiers 2 and 3) and long-term (Tier 4) validation objectives. Accordingly, this project will provide the IWYP Hub, partner breeding companies, and the wider wheat breeding community with a phased release of validated near isogenic material & knowledge in regionally adapted genetic backgrounds for subsequent breeding activities.

The research will benefit wheat improvement programmes in developed and developing countries because there is global interest in understanding how to optimise root systems for a range of environments. Improved root systems should increase the capture and utilisation of nutrients and water, and decrease losses of nutrients to groundwater through leaching. These factors will contribute to the sustainability of growing wheat in both high input and low input farming systems. In this project we aim to collaborate where possible with other initiatives and projects aimed at improving root systems within the CG centres and by academic groups around the world. Specifically, information on controlled environment and field phenotyping of root ideotypes to support yield potential will foster collaboration across IWYP Programme projects focussed on above-ground traits. Communication and sharing of ideas, results, markers and germplasm with other research efforts will provide mutual benefits.
The potential impact on livelihoods is extensive, as the project's pipeline of tools (e.g. molecular markers and germplasm) to improve wheat varieties is delivered to plant breeders in the public and private sector. The commercial breeding companies involved in the project sell seed for food production in many LMICs, taking advantage of large distribution networks, and their markets are not limited to Europe and North America. In the public sector, by using elite (high yielding) lines currently used by CIMMYT breeders in Mexico and Turkey as recurrent parents for the proposed backcrossing programme, the resulting lines produced in the project should feed directly into their variety improvement programmes.