A ‘breeder’s tool kit’ to improve Hagberg Falling Number in UK wheat

Abstract

Hagberg Falling Number (HFN) is one of the principal standards against which the UK wheat crop is routinely assessed for bread-making quality. Low HFN for wheat grown for the bread-making market can present a serious problem, through reducing grower’s margins and increasing costs in the processing industries.

The most effective and sustainable option for achieving consistent HFN for bread-making specifications and export premiums is through appropriate varietal selection. Considerable progress has been made in understanding the genetic systems involved in HFN, primarily through an AHDB/BBSRC-funded LINK project (Report No. 480). There existed an opportunity to turn this knowledge into a ‘breeder’s tool kit’, based on advanced molecular tools. The ultimate aim was the development of new wheat varieties with increased and more stable HFN under variable weather conditions.

We have cloned a major gene affecting pre-harvest sprouting in UK wheat (4A QTL) and developed a high-throughput perfect SNP marker which allows breeders to tag the functional polymorphism which confers resistance to pre-harvest sprouting. We screened UK germplasm based on this SNP marker and have identified different versions of the chromosome region (haplotypes). This information is now being implemented by breeding partners to deliver varieties with enhanced sprouting resistance to UK growers.

We have prioritised two additional genes which confer resistance to sprouting (1A) and pre-maturity amylase, PMA (7B). We show that these genes do not affect yield and provide an increase in HFN of 25 and 32s, respectively. Importantly, these genes have distinct mechanisms of action, which suggests that combining them could lead to average increases in HFN of over 50s and also could provide alternative resistance mechanism that could be triggered independently depending on weather events for the particular year. Both genes have been mapped to relatively small genetic intervals and breeder friendly markers and transferred to industrial partners to enable rapid targeted deployment into UK elite varieties.

We have developed a new tool (PolyMarker) to improve the speed of transfer of SNP from fixed platforms (e.g. iSelect 90k chip) into functional assays that can be routinely implemented in a high-throughput manner in breeders’ molecular laboratories. This accelerates the rate in which new genomic information can be deployed for the benefit of UK growers. This tool is open source and is being used to generate markers for many additional traits within the breeding community. This project, alongside advances by others in the field, has now made marker-assisted selection for high HFN a reality in UK wheat breeding programmes.