Production of wheat lacking B-type starch granules

Lead Research Organisation: John Innes Centre
Department Name: Crop Genetics

Abstract

Starch is a major component of cereal grains and its functional properties have a significant impact on grain utilisation. Of considerable importance is the size and shape of the starch granules. In wheat, barley, rye and most of their wild grass relatives, there are two types of starch granules, called A- and B-type. These differ in size, leading to a bimodal granule-size distribution that is unusual amongst plant starches and not found in other grasses, including Brachypodium, oats, rice and maize.
The smaller, B-type starch granules have negative impacts on many end-uses of wheat and barley. So far, attempts to reduce or remove B-granules from these crops by breeding have failed. The reason for this is the lack of genetic variation in B-granule content between cultivars. However, there is much greater variation for this character between species of Aegilops (Goat Grass), wild grasses that include the ancestors of bread wheat. The existence of Aegilops species lacking B-granules suggests that it should be possible to introduce variation for B-granule content into the closely-related crop species.
The project builds on previous work in which we identified a major QTL controlling the content of B-type starch granules in Aegilops. Our ultimate goal is to identify and manipulate the gene responsible for the control of B-granule content in wheat and barley, Bgc-1. In this project, we will investigate gene order in the region of the genome harbouring Bgc-1 and compare it with that in other grasses. If the opportunity arises within our project's timeline, we will be ready to use the latest developments from ongoing genomics projects in other labs to identify the orthologs of Bgc-1 in wheat and barley and we will begin to manipulate Bgc-1 in these crops using RNAi and TILLING technologies.
Prior to the identification of Bgc-1, we will start to produce mutant wheat plants lacking B-granules using a pre-existing collection of deletion lines of a breadmaking wheat cultivar Paragon. Previously, this population has been successfully used to generate wheat mutants with novel phenotypes by stacking deletions of genes. By screening for deletions spanning the Bgc-1 region, we can select lines likely to lack Bgc-1 in each of the three genomes of wheat and then stack these into a single plant by repeated rounds of crossing and selection.
This project will produce: 1) a fine map of the Bgc-1 region and possibly identification of the Bgc-1 gene in Aegilops and a comparision of this region/gene with those in other grasses. 2) near-isogenic lines of wheat and Aegilops that will allow functionality testing to determine the utility of B-granule-less grains. In addition, if Bgc-1 is identified, the production of genetically manipulated lines of wheat and barley and/or TILLING mutants lacking B-granules will be underway by the end of the project.

Technical Summary

We recently made a significant breakthrough in our understanding of the control of B-granule content in the Triticeae: a population of Aegilops segregating for B-granule content was used to identify a major QTL that is responsible for B-granule content. Subsequently, we have made progress towards fine mapping the Bgc-1 gene using the same Aegilops population. Refinement of the phenotyping procedure together with the use of homozygous recombinant lines has enabled conversion of the trait from a QTL to a simple qualitative (Mendelian) trait. Within this project we will extend the fine mapping to define a sub-cM interval encompassing the Bgc-1 locus. As the genome sequence of Aegilops (or any other Triticeae) is unknown at present, we cannot be certain of identifying Bgc-1 by fine-mapping alone. However, we are optimistic that ongoing genomics projects in wheat, Aegilops and other cereals are generating tools and resources that will facilitate its identification.
Prior to the identification of Bgc-1, we will begin to select lines likely to lack this gene by screening a wheat deletion-mutant population for deletions spanning the Bgc-1 region. In this Paragon population, the deletions vary in size but include ones of ~10cM that eliminate multiple contiguous genes. The high level of conserved gene order observed between grass species in the region containing Bgc-1 and the close taxonomic relationship between wheat and Aegilops makes it highly likely that the wheat homoeologs of Bgc-1 will be in syntenous positions. The B-granule content and functional properties of the grains and starches isolated from the wheat deletion mutants and from recombinant inbred lines of Aegilops will be tested. The improved lines with the most useful characteristics will be bulked up and grain will be made available at the end of the project for end-user trials e.g. bread and baking trials, mashing and alcohol yield trials.

Planned Impact

Government policies recognise the need to improve grain quality whilst maintaining or enhancing yield. Thus, genetic improvements affecting critical processing attributes, such as starch functionality, are encouraged. The smaller, B-type starch granules present in the grains of wheat and barley are known to have negative impacts on many end-uses. However, efforts to breed wheat and barley cultivars with altered B-granule content have failed because variation in granule-size distribution among elite wheat and barley cultivars is almost non-existent. In contrast, amongst the closely-related wild grasses (Aegilops), there are some species which lack B-granules. This project is designed to provide a deeper understanding of the control of B-granule content in Aegilops, thus allowing the introduction of novel variation for this trait into the related crop species. It has been submitted to the CIRC initiative as it is clear the project is directly relevant to the objectives of many stakeholders, providing as it does the means to achieve a step-change in grain quality. The proposed work is directly relevant to the BBSRC key strategic aims of 'advancing fundamental understanding of complex biological processes' and of 'helping to provide the skilled researchers needed for industrial R&D and academic research'.

Who will benefit from this research?

Plant breeders, millers/bakers, brewers/distillers, farmers

How will they benefit from this research?

UK breeders will benefit from the introduction of novel genetic variation for a key parameter affecting starch functionality that is at present not available in elite wheat and barley cultivars and will provide UK growers with new market opportunities. Scientists in both the academic and commercial private sectors will benefit from the Aegilops grain and leaf RNA sequence database, which is an open-ended resource. The lack of B-granules in wheat is predicted to improve milling and baking functionality and reduce the waste associated with wet processing procedures. In barley, the B-granule-less grains are predicted to enhance processing and the quality and alcohol yield of the final product. Importantly, the introduction of novel grain quality should be achieved in both crops without major impacts on yield.

Our data and germplasm, after appropriate protection of IP in accordance with the special conditions relating to CIRC, will be released into the public domain and will be available to industrialists and academics worldwide. It will contribute directly to wheat (and ultimately to barley) breeding in the UK by producing breeding lines that better meet the needs of end-users. The use of genetic/genomic information from /other cereal systems to help define candidate genes will provide a paradigm for other similar work. The development and release of gene-based markers will aid breeders in manipulating the B-granule trait in elite wheat varieties.
 
Description We have identified a region from wild Aegilops that is required for the initiation of B-type starch granules in wheat. This gene, Bgc-1, has been mapped and we are now developing closely linked markers to identify mutants in bread wheat to reduce B-granule content. Continuing on from that we have identified a candidate gene which we have now validating. The identification of this gene allows new possibilities to engineer starch quality.
Exploitation Route The findings will allow the development of wheat lines with reduced B-granule content and expected changes in starch functionality.
Sectors Agriculture, Food and Drink

 
Description We have shown the effect of B-granule less wheat on flour properties. We now have a follow on fund to understand how this will impact bread making on a larger scale. Partners of the Crop Improvement Research Club are aware of these developments.
First Year Of Impact 2015
Sector Agriculture, Food and Drink
Impact Types Economic

 
Description UK Global Food Security Science Advisory Board
Geographic Reach Multiple continents/international 
Policy Influence Type Participation in a advisory committee
URL https://www.foodsecurity.ac.uk/
 
Title Wheat Training 
Description This website provides background information and practical resources to help both budding wheat scientists as well as researchers looking to expand their work into wheat. There is a need to improve crops to feed the world's growing population with the backdrop of climate change. Translation of fundamental plant biology research (e.g. from Arabidopsis thaliana) into crops such as wheat provides a potential route to deal with this challenge. However learning even simple tasks such as growing and crossing wheat plants requires time and effort, while material and methods sections in published articles are often short and cannot substitute teaching aids. This is also true for more complex topics such as the genomics aspect of wheat. 
Type Of Material Database/Collection of data 
Year Produced 2016 
Provided To Others? Yes  
Impact >4,500 sessions from >2,700 users 
URL http://www.wheat-training.com/
 
Description A meeting between CIMMYT and DFW funded by BMGF to discuss collaboration projects 
Organisation International Centre for Maize and Wheat Improvement (CIMMYT)
Country Mexico 
Sector Charity/Non Profit 
PI Contribution I organised a meeting funded by Bill and Melinda Gates Foundation brought together members of the BBSRC's coordinated wheat programme (Designing Future Wheat) with members of CIMMYT (who breed wheat for the resource poor in the developing world), discuss potential opportunities for interaction. These opportunities are taken forward by writing proposals for Newton , GCRF or IWYP funding calls
Collaborator Contribution See above
Impact This interaction is still ongoing between members of BBSRC's coordinated wheat programme (Designing Future Wheat) and researchers within CIMMYT with proposals being written for IWYP and Newton calls
Start Year 2018
 
Description Bayer 
Organisation Bayer
Department Bayer CropScience Ltd
Country United Kingdom 
Sector Private 
PI Contribution Wheat genetics and genomics
Collaborator Contribution Wheat breeding and molecular knowledge
Impact joint projects
Start Year 2012
 
Description KWS 
Organisation KWS UK
Country United Kingdom 
Sector Private 
PI Contribution Genetics and genomics
Collaborator Contribution Breeder know how and germplasm
Impact joint projects
Start Year 2009
 
Description Limagrain 
Organisation Limagrain
Country France 
Sector Private 
PI Contribution Genetics and genomics
Collaborator Contribution Germplasm and breeder know-how
Impact Phd Studentship, field trails, among others
Start Year 2009
 
Description RAGT 
Organisation RAGT Seeds
Country United Kingdom 
Sector Learned Society 
PI Contribution Genetics and genomics
Collaborator Contribution Wheat germplasm and know how
Impact Shared projects
Start Year 2009
 
Description Agricultural Industries Confederation 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach National
Primary Audience Industry/Business
Results and Impact Agribusiness Meeting: A step change in plant breeding to achieve a UK competitive advantage
Year(s) Of Engagement Activity 2016
 
Description BBSRC Food Priming Partnership Workshop 
Form Of Engagement Activity A formal working group, expert panel or dialogue
Part Of Official Scheme? No
Geographic Reach National
Primary Audience Professional Practitioners
Results and Impact BBSRC Food Priming Partnership Workshop
Year(s) Of Engagement Activity 2018
 
Description Discussion Norman Lamb, MP 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach National
Primary Audience Policymakers/politicians
Results and Impact Discussion Norman Lamb, MP
Year(s) Of Engagement Activity 2017
 
Description Discussion with Gov Office Science 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Policymakers/politicians
Results and Impact Discussion with Gov Office Science
Year(s) Of Engagement Activity 2017
 
Description Discussions with Syngenta 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Industry/Business
Results and Impact Discussions on collaborations
Year(s) Of Engagement Activity 2018
 
Description GARNish27. "Spotlight on NIAB" June 2017 
Form Of Engagement Activity A magazine, newsletter or online publication
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Professional Practitioners
Results and Impact Alison Bentley authored an article in GarNish that featured two BBSRC-funded projects from the Trafford lab: the B-granule project and the large-embryo project. The impact was publicity for NIAB research in general and for the two BBSRC-funded projects in particular.
Year(s) Of Engagement Activity 2017
 
Description Gatbsy Plant Science Students 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach Regional
Primary Audience Schools
Results and Impact Can wheat genomics help alleviate food insecurity?
Year(s) Of Engagement Activity 2017
 
Description Italian Society of Genetics (SIGA) and Plant Biology (SIBV) Joint meeting 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Postgraduate students
Results and Impact Keynote at PISA
Year(s) Of Engagement Activity 2017
 
Description JIC Open day 
Form Of Engagement Activity Participation in an open day or visit at my research institution
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Professional Practitioners
Results and Impact JIC Open Day
Year(s) Of Engagement Activity 2018
 
Description JIC Science Innovation Showcase 
Form Of Engagement Activity Participation in an open day or visit at my research institution
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Industry/Business
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Year(s) Of Engagement Activity 2018
 
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Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Industry/Business
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Year(s) Of Engagement Activity 2017
 
Description Rachel Lambert, Senior Livelihoods Adviser, Agriculture Research DFID 
Form Of Engagement Activity A formal working group, expert panel or dialogue
Part Of Official Scheme? No
Geographic Reach Local
Primary Audience Policymakers/politicians
Results and Impact Rachel Lambert, Senior Livelihoods Adviser, Agriculture Research DFID
Year(s) Of Engagement Activity 2018
 
Description Talk Aarhus 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Postgraduate students
Results and Impact Talk at Aarhus University
Year(s) Of Engagement Activity 2017
 
Description • EPSO-EC Conference at EXPO Milano 
Form Of Engagement Activity A formal working group, expert panel or dialogue
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Policymakers/politicians
Results and Impact EU meeting on new breeding technologies
Year(s) Of Engagement Activity 2015