UK-Brazil partnership.

Lead Research Organisation: Rothamsted Research
Department Name: Plant Biology & Crop Science

Abstract

The proposal is for a small project which, if successful, would represent a major step forward in our understanding of genes controlling cell wall properties of grasses, which include not only grassland crops but also major food crops such as wheat, rice and sugar cane. These cell walls represent the great majority of biomass in grass vegetation and therefore are the main constituent of by-products of crop food production such as cereal straw and sugar cane residues. If they could be made more digestible, these huge amounts of biomass would become more valuable for bioethanol production and for animal feed. It is believed that feruloylation in grass cell walls makes them less digestible by linking the polysaccharide sugars to lignin, which inhibits digestion. However the genes responsible for feruloylation are unknown. We have identified candidate genes in the BAHD gene family and have designed a DNA sequence to specifically suppress the acitivity of these genes in a model grass species (Brachypodium distachyon). The proposed work is to introduce this sequence into the Brachypodium plants and then compare the GM plants with control plants. We will therefore determine if feruloylation has been decreased by suppressing the BAHD genes. If it has, these plants will become invaluable tools for studying feruloylation of cell walls and the way it affects the properties of the cell walls. In particular, we will study the impact on digestibility of biomass.

Technical Summary

The proposal is for a small project which, if successful, would represent a major step forward in our understanding of genes controlling grass cell wall properties. These cell walls represent the great majority of biomass in grass vegetation and by-products of crop food production such as wheat straw and sugar cane residues. If they could be made more digestible, these huge amounts of biomass would become more valuable for bioethanol production and for animal feed. It is believed that feruloylation in grass cell walls makes them less digestible by linking the polysaccharide sugars to lignin, which inhibits digestion. However the genes responsible for feruloylation are unknown. In a previous project, we have already identified all the candidate genes within the BAHD family that are highly expressed in Brachypodium distachyon. An RNAi construct has been designed to specifically suppress expression of all 8 of these genes in Brachypodium. Two versions of this RNAi construct have been created, one driven by a constitutive promoter and one by a IRX3-1.5kb upstream region isolated from Brachypodium which we expect to act as a strong secondary cell wall specific promoter. The proposed work is to transform Brachypodium plants with these constructs and then analyse the cell wall feruloylation using a protocol that we have already applied extensively to Brachypodium tisssues. We will therefore determine if feruloylation has been decreased by suppressing the BAHD genes. If it has, these plants will become invaluable tools for studying feruloylation of cell walls and the way it affects the properties of the cell walls. In particular, we will study the impact on digestibility of biomass as part of a wide investigation of the cell walls of the transgenic plants.

Planned Impact

Societal:
Since use of lignocellulose feedstock for biofuel has far greater benefits for CO2 emissions than starch or sugar, a successful outcome in showing a means for increasing digestibility of grass biomass would be a step towards reducing emissions in Brazil and UK and would reduce competition between food and fuel for land.

Academic:
Grass cell walls are a topic of great interest worldwide and the major evolutionary division between dicots and grasses is in the feruloylation of xylan in grass cell walls. Therefore definitive evidence that the BAHD gene candidates are responsible for feruloylation would have major importance for our understanding of evolution of cell walls and would be a high impact publication.

Commercial:
Identification of genes responsible for feruloylation may open opportunites for developing new varieties with increased digestibility of biomass for animal feed.

Publications

10 25 50
 
Description This grant established the collaboration that eventually led to the key discovery made as part of grant BB/K007599/1 i.e. the discovery of the BAHD genes that are responsible for linkage between lignin and polysaccaharide in grass cell walls. Cell wall polysaccharides contain the sugars that are used to make biofuels from the non-food parts of crops. However these are hard to digest from polysaccharide into sugar because of the inhibitory lignin. Therefore identification of the gene responsible for the lignin-polysaccharide linkage is important as it provides a route to decrease amount of linkage and make polysaccharide more digestible. As part of our collaboration with Embrapa-Agroenergy, formed in this project we were able to show that suppression of the activity of the gene did indeed greatly increase digestibility of biomass in grasses.
Exploitation Route Our Brazilian partners are applying the discoveries to develop sugar cane with more digestible biomass (paper under review). This could have massive benefits for production of biofuels from sugar cane residues making bioethanol production more economic. This is a key requirement to reduce reliance on fossil fuels and thereby reduce CO2 emissions.

We are continuing our collaboration to compare alternative approaches for improving digestibility of grass biomass to identify the most promising approaches for differing end uses- use of sugarcane residues for biofuel, digestibility of pasture grasses for ruminants.
Sectors Agriculture, Food and Drink,Manufacturing, including Industrial Biotechology

URL http://onlinelibrary.wiley.com/doi/10.1111/nph.14970/full
 
Description This grant established a collaboration which is still ongoing and allowed us to achieve key outputs in other projects. Our embrapa-agroenergy partners are now translating the latest findings to sugarcane to improve digestibility of residues for bioethanol production.
First Year Of Impact 2018
Sector Agriculture, Food and Drink,Manufacturing, including Industrial Biotechology
Impact Types Societal

 
Description Newton Award: Comparing alternative technologies for genetic improvement of digestibility of Brazilian grass crops
Amount £8,225 (GBP)
Organisation Biotechnology and Biological Sciences Research Council (BBSRC) 
Sector Public
Country United Kingdom
Start 09/2018 
End 03/2019
 
Description RCUK-CIAT Newton Fund
Amount £149,481 (GBP)
Funding ID BB/R022828/1 
Organisation Biotechnology and Biological Sciences Research Council (BBSRC) 
Sector Public
Country United Kingdom
Start 04/2018 
End 03/2019
 
Title Setaria RNAseq 
Description RNAseq transcriptome of Setaria viridis BAHD01 RNAi transgenics 
Type Of Material Database/Collection of data 
Year Produced 2017 
Provided To Others? Yes  
Impact Demonstrated specific repression of SvBAHD01 gene and pleiotropic effects on other genes, as reported in de Souza et al. (2018) 
URL https://www.ebi.ac.uk/arrayexpress/experiments/E-MTAB-5648/
 
Description EMBRAPA-Agroenergy Brazil 
Organisation Brazilian Agricultural Research Corporation
Country Brazil 
Sector Public 
PI Contribution we have hosted members from their lab and helped them identify targets and methods
Collaborator Contribution they have conducted parallel experiments in their labs on species closer to the target crop, sugarcane
Impact joint paper in press
Start Year 2010
 
Description Interview for The Times national newspaper 
Form Of Engagement Activity A press release, press conference or response to a media enquiry/interview
Part Of Official Scheme? No
Geographic Reach National
Primary Audience Public/other audiences
Results and Impact As a result of our press release for de Souza et al. (2018) New Phytologist article I was interviewed by The Times resulting in article "Grass may soon be greeener with superfood for hungry cows" January 8 p. 15. as a result of this I have received 4 contacts from companies interested in testing novel pasture grasses.
Year(s) Of Engagement Activity 2018
 
Description Presentation and discussion with seed technical working group 
Form Of Engagement Activity A formal working group, expert panel or dialogue
Part Of Official Scheme? No
Geographic Reach National
Primary Audience Industry/Business
Results and Impact Invited presentation to Herbage Seed Technical Working Group Meeting 2019

Presented potential for our plant science to feed into genetic improvement of pasture grasses
Year(s) Of Engagement Activity 2019
 
Description interview - Nexus media 
Form Of Engagement Activity A press release, press conference or response to a media enquiry/interview
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Public/other audiences
Results and Impact Interview following press release for de Souza et al. (2018)
Year(s) Of Engagement Activity 2018
URL https://nexusmedianews.com/good-news-for-cows-scientists-unlock-hidden-energy-in-grass-3aa4ce33cf41
 
Description interview - genetic literacy 
Form Of Engagement Activity A press release, press conference or response to a media enquiry/interview
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Public/other audiences
Results and Impact Interview following press release for de Souza et al. (2018)
Year(s) Of Engagement Activity 2018
URL https://geneticliteracyproject.org/2018/02/27/engineering-digestible-grass-reduce-livestock-pastures...
 
Description press release 
Form Of Engagement Activity A press release, press conference or response to a media enquiry/interview
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Industry/Business
Results and Impact To advertise the implications of our discovery of a grass-specific gene that determines cell-wall feruloylation : suppressing the gene increases biomass digestibility with no penalty in growth leading to the prospect of new grass crops that are better for animal nutrition and biofuels. This led to coverage in more than 40 news outlets in English and Portuguese.
Year(s) Of Engagement Activity 2018
URL http://www.bbsrc.ac.uk/news/industrial-biotechnology/2018/180110-n-less-chewing-the-cud-more-greenin...