A 'breeder's tool kit' to improve Hagberg Falling Number for the economic and environmental sustainability of UK wheat

A harvested wheat crop is normally assessed for several quality attributes that influence the ability of its flour to make bread and also affect the money paid to farmers by millers. One such parameter is called Hagberg Falling Number (HFN) which is an indirect measure of the properties that a loaf of bread will have. For example, wheat with low HFN will produce bread that is very difficult to slice because of sticky crumb. Therefore, millers and other end-users avoid buying wheat grain that has a HFN value below a fixed number. Low HFN wheat impacts negatively on the environment as it produces wastage and inefficient use of resources. Unlike other problems in wheat which can be corrected by agronomic practices or through disease management, HFN is heavily influenced by the environment and cannot be easily improved by these means. This is especially relevant in the UK environment as cold and wet periods during the summer are thought to reduce HFN. Therefore, the most effective and reliable way for a farmer to grow high HFN wheat is proper varietal selection. Unfortunately, it is very difficult for breeders to develop high HFN varieties due to lack of knowledge of the genes, or regions throughout the genome, which might influence HFN. Through a previously funded Defra-BBSRC project we have made important progress in understanding the variation for HFN in UK wheat varieties and have taken a first step to discovering the regions of the genome that affect this trait. Despite these encouraging results, we are still short in developing the tools that breeders require to transfer this knowledge into improved commercial wheat varieties. This projects seeks to address this limitation by developing a 'breeder's tool kit' that will assist towards this end. We have selected six regions of the wheat genome which we know are affecting HFN based on experiments conducted in the previous project. We will now hone in and develop more precise information of these regions. This will result in better defined genetic maps which breeders can use to navigate the wheat genome and focus their breeding efforts more effectively in those locations that contain genes affecting HFN. We will investigate how these regions affect agronomic traits which are of interests to breeders and farmers; such as yield and other quality characteristics. We will also combine the six regions in different combinations to better understand how they work together and if we can produce more resilient varieties that will have high HFN values independent of the weather conditions. We will also investigate the basic biology of how these regions affect HFN. Together, this information will enable UK plant breeders to develop new, more competitive varieties of wheat with reduced environmental footprint and more consistent grain quality.

Hagberg Falling Number (HFN) is one of several standards against which the UK wheat crop is routinely assessed for bread-making quality. Low HFN is a serious problem reducing grower's margins, increasing costs in the processing industries and with many negative environmental impacts. The most effective and sustainable option for achieving consistent HFN for bread-making specifications and export premiums is through proper varietal selection. Considerable progress has been made in understanding the genetic systems involved through the Defra-BBSRC-funded LINK project (LK0975, 2005-2010). Despite the success of this initial discovery phase, several factors restrict the use of the project outcomes in commercial breeding programmes. There is now an opportunity to address these limitations and convert this knowledge into a 'breeder's tool kit' allowing high throughput marker-assisted selection. We have selected QTL (chromosomal regions) which have been prioritized based on stability, effect on pre-harvest sprouting (PHS)/HFN and their importance to both academic and industrial partners. We propose an extended partnership to identify and validate closely linked markers associated with these QTL to allow marker assisted breeding of new wheat varieties with improved HFN and resistance to PHS. We will evaluate interactions between these QTL in isogenic genetic backgrounds and determine their effect on yield related traits and agronomic characteristics. We will also use the precise germplasm generated in this proposal for controlled physiological experiments to characterize seed dormancy mechanisms and to exploit new technologies to accelerate marker development. This information will enable UK plant breeders to develop new, more competitive varieties of wheat with reduced environmental footprint and more consistent grain quality.

The most important impact of this research is the development of a 'breeder's tool kit' (including tightly linked molecular markers for validated and clearly defined QTL) that will enable breeders to develop new varieties of bread wheat with stable HFN and bread-making quality under variable weather conditions. There are many environmental and economic costs associated with PHS/HFN that have a detrimental effect on the overall competitiveness and sustainability of the UK arable industry. Genetic improvement of PHS/HFN would have a profound impact on reducing these negative externalities across the production sector. We expect several different beneficiaries of the proposed work, including the private sector in the form of wheat farmers and breeding companies, the UK environment, and the wider public in general. Breeders, farmers, and Industry: -In the last three years, almost 40% of the nabim Group 1 acreage grown for bread-making in the UK has failed to meet the minimum HFN requirement, with an average of over 27% over the last decade. Bread-making wheat that fails to make the Hagberg quality threshold is usable only as animal feed, incurring a drop in price of up to 28% (£37/tonne, Aug 2009). Therefore, many growers lose the premium essential to grow Group 1 varieties profitably. This also has a knock-on effect on the price of feed wheat, reducing all UK wheat growers' incomes still further. - As part of the 'breeder's kit' we will generate the necessary experimental germplasm to determine how these QTL interact with each other and evaluate their effect on important agronomic performance characters such as yield, crop establishment, quality, height, etc. This information will allow the best combinations of alleles to be deployed in breeding programmes and will significantly increase the likelihood of uptake. - Currently, overseas wheat represents approximately 15-20% of UK milling grists. The economic cost of importing over one million tonnes of wheat to the UK exceeded £150 million in 2008/09. The ability to produce high quality wheat with reliable HFN would significantly decrease these import costs and possibly open export markets. - The identification of validated molecular markers for genomic regions that confer reliably high HFN will enable the industrial partners to screen breeding material for this complex trait in early generations, thus improving the efficiency of variety development. This is of critical importance for industrial competitiveness as breeding material for all nabim groups requires a minimum HFN standard to be included on the HGCA Recommended List. UK environment and society: - Increased and stable HFN will decrease reliance on imports of bread-making quality wheat [over one million tonnes annually, including 45% from non-EU members (2008)], thereby reducing the environmental and economic costs of overseas transport. - Increased tolerance to adverse weather will decrease the need to harvest wheat before fully mature, a practise used to avoid a decrease of HFN in the field. This will reduce the requirement for costly grain drying, minimising energy use (drying can account for ~10-15% of wheat production energy use), reducing CO2 emissions and improving the commercial and environmental sustainability of UK wheat. - Wheat crop that is grown for bread-making often requires extra N applications to meet protein specifications. Considering group 1 acreage and percent failure to meet HFN specifications, a surplus of over 11,550 tonnes N/annum have been applied in the last three seasons. This is especially relevant considering that ~45% of CO2 emissions from wheat production inputs are due to N fertilizers. This significant environmental and economic impact could be reduced with the outcomes of this project. Increased reliability of wheat HFN will allow these N applications to be better targeted at crops that will have a higher probability of meeting the bread-making quality threshold.