Enhancing diversity in UK wheat through a public sector prebreeding programme

Food security is becoming a critical issue both in the UK and worldwide due to rapid population expansion, dietary changes, climate change and declining fossil fuel stocks. In the next 50 years, we will need to grow as much wheat grain as has been produced since the beginning of agriculture, some 10,000 years ago. The requirement to enhance the amount of wheat grown in the UK creates a major challenge for research. We need to develop new wheat varieties which have higher yields with lower nutrient requirements, whilst retaining the quality of the grain. Historically the Plant Breeding Institute (PBI) made experimental crosses with wild wheats and related grasses, capable of transferring traits of high agronomic potential into wheat, but still requiring further breeder selection to generate varieties with elite performance. However, the PBI was privatised in 1987 and research developing new experimental crosses of this kind almost stopped. This has created a major bottleneck for wheat breeders, because they do not have the necessary new experimental lines from which to develop new varieties with increased yield. The objective of this proposal is to re-establish a pre-breeding programme in wheat developing such experimental crosses in the UK. Such a pre-breeding programme will produce wheat germplasm, characterised for the next generation of key traits, such as yield, and will identify genetic markers for selecting these traits, in breeding programmes and for the academic community. We will develop novel pre-breeding wheat germplasm, using three different but complementary strategies, to maximise the introduction of diversity and beneficial traits into a range of wheat lines. First we will develop germplasm from crosses involving wheat landraces or locally adapted varieties, derived from exiting germplasm collections. Secondly we will create synthetic hexaploid wheats by artificially crossing tetraploid or 'pasta' wheats with diploid wheat progenitors. This captures diversity in both the tetraploid and diploid wheat progenitors. The potential of these synthetics is illustrated by their success in the CIMMYT breeding programme. Thirdly we will use a technique called alien introgression, to transfer small segments of chromosomes of wild relatives containing the target genes, into wheat. Wild and cultivated relatives (alien species) provide a wealth of genetic variation for all characters of importance relative to yield, climate change and the environment. The impact of this approach has been illustrated by the transfer of rust resistance by Sears in the US saving its economy several billion dollars in the intervening years. The parental material used in the initial prebreeding crosses will be characterised to ensure the maximal levels of diversity are being exploited. New sequencing technologies will be used to generate very high density maps, providing the breeding companies with markers for 'precision' breeding, and the academic researchers with markers for fine dissection of key traits. Key target traits relating to yield, of interest to both UK breeders and academics, have been identified. We will screen for, biomass and enhanced N and P use efficiency, Take-All and insect resistance including Bulb fly and Aphids. The programme will not involve the actual cloning of the genes responsible for these particular traits, but will provide the germplasm as the starting point for such projects. The new germplasm generated in this project will be exploited by breeders for crossing with their elite lines to develop new varieties for use by farmers. All the information generated in the programme will be stored in a central database, and seed stored centrally, both being freely available within the UK to both academics and breeders alike.

We propose a pre-breeding wheat programme to develop novel populations containing key agronomic traits as starting materials for the development of new varieties by plant breeders and the main resource for understanding the biological basis of these key traits. In collaboration with key stakeholders we have identified the most relevant and important yield and quality traits to study. We will focus on biomass and nutrient use efficiency, Take-all resistance and resistance to Bulb fly and Aphids. The programme will be structured around three complementary 'pillars', each of which will broaden the pool of genetic variation in wheat by a different route. The first will develop germplasm from crosses involving wheat landraces or locally adapted varieties, derived from the 'Watkins' and other collections. The second will create synthetic hexaploid wheats by artificially crossing tetraploid wheats with diploid wheat progenitors. This will capture diversity in both the tetraploid and diploid wheat progenitors. The third will use alien introgression to transfer small segments of chromosomes of wild relatives containing the target genes, into wheat. Wild and cultivated relatives (alien species) provide a wealth of genetic variation for all characters of importance relative to yield, climate change and the environment. A fourth pillar, which will involve the production of the elite performing wheat, will be undertaken independently by the breeding companies. The parental material used in the initial crosses will be genotyped, ensuring the maximal levels of diversity are being exploited. Next generation sequencing will generate very high density maps, providing the breeding companies with markers for 'precision' breeding, and academics with markers for fine dissection of key traits. Detailed phenotypic characterisation of the material will identify the best lines to be taken forward by the breeders and/or the academic partners to dissect the biology of the key traits.

The development of a prebreeding programme to support the development of new varieties of wheat, a key crop for the UK, will have a major impact in addressing elements of the global challenge of food security. The beneficiaries of this work will be the UK wheat breeding community, the academic wheat community, international breeding centres and the Developing world. UK wheat breeders. The UK private wheat breeders have been consulted and engaged at every stage of the development of this proposal to ensure that this proposal and the consequent outputs are entirely relevant to their requirements. In recognition of the potential impact of this work, the British Society of Plant Breeders (BSPB), have written to BBSRC giving their strong support to the initiative. In discussion with the breeders, we have defined the populations, genotyping and phenotyping to be undertaken, with the collective objective of generating germplasm characterised for increased biomass, resource use efficiency and resistances to disease and insects. These are priority biological targets that the breeders have identified as being of most importance to them. Thus, as the germplasm is generated and characterised during the course of the programme, it will be available for trialling by the breeders within their own programmes. In addition, the breeders will be key stakeholders on the steering committee for the programme, ensuring that they remain informed and influential in determining the focus on specific populations to be generated and traits to study. This engagement will maxmise the BBSRC investment in relation to the development of economically relevant varieties. The programme will provide a direct bridge between the UK plant community funded by BBSRC and the privately funded wheat breeding programmes. Economic impact. The USDA reviewed the impact of the PBI pre-breeding programme before it closed in 1987. It concluded that the investment return of this programme for the UK economy covered the costs of all future research of an institute like the John Innes Centre well into the 21st century. There are clear examples of the exploitation of wild relatives and exotic germplasm to introduce novel resistance, yield or drought characteristics into wheat which have resulted in economic impacts globally of hundreds of million and in some cases billions of dollars. One example being the dwarfing gene for the green revolution introduced via a Japanese wheat Norin 10 from a Japanese landrace Shiro Daruma. Close on half the resistance genes for stem rust and leaf rust resistance originated in species which were not either bread or pasta wheats. More recently 25% of wheat now produced for Developing countries from CIMMYT's wheat programme is derived from wheat synthetics. If a novel source of Take-All resistance in wild species can be transferred to wheat, this would substantially alter european farming and crop rotation. International Breeding Centres. Many of the academics within this programme are also involved in interactions with CIMMYT, INRA, GATES foundation and wheat breeding programmes in the US and Australia. There is the opportunity during the course of this programme to enhance the exploitation of the germplasm generated by making it available through interactions with these international centres as many of the targets identified are also important to their own breeding programmes. Social and Training impact. Following privatisation of the PBI, wheat researchers with a whole range of skills have become dispersed across different types of institutes and universities in the UK. This programme will bring that skill base together, providing a framework within which young researchers can be trained in a wide range of skills involved in population development, genotyping and phenotyping. These key skills will be required to underpin future UK wheat programmes both in the public and private sectors.