In 2013 the BBSRC provided funding for 13 Networks in Industrial Biotechnology and Bioenergy (NIBB) each of which had the principle aims of supporting ‘Proof of Concept’ style projects and providing a forum for like-minded researchers to interact with each other and with industry. Each of these NIBBs are set up in much the same way although the manner in which they have developed has slightly varied.
GARNet has recently promoted the activities of the High Value Chemicals from Plants network and in order to learn about another group of researchers I recently attended the 1st International Conference of the Lignocellulosic Biorefinery Network (LBNet). This three-day residential meeting brought together both academics and representatives from industry who use a variety of experimental approaches to tackle the challenges associated with utilising the biomass held within plant cell walls. The conference schedule was split into broad sections that each focused on structural aspects of the cell wall, namely ‘Lignin’, ‘Matrix Polysaccharides (MS)’ and ‘Cellulose’. Within each of these was a ‘Construction’ and ‘Deconstruction’ sections which broadly, although not exclusively could be summarised as ‘Plant’ or ‘Bacterial’ respectively!
GARNets favourite model plant is not usually thought of as a potential source of usable biomass so it was encouraging to observe that much of the plant science discovery research was indeed occurring in Arabidopsis. This again provides evidence for the utility of Arabidopsis as a model plant despite recent moves to encourage researchers to also embrace other experimental systems.
Following an introduction from the LBNet chairman Simon McQueen-Mason, the ‘Lignin Construction’ session kicked off with both Claire Halpin (Dundee) and Wout Boerjan (VIB, Ghent) describing the use of Arabdopsis mutants to identity components of lignin signaling pathways. Lignin provides a major difficulty for the saccharification of sugars from plant biomass so a prime objective in this field is to identify plants that have reduced lignin composition yet do not show any yield penalty.
Professor Boerjan introduced a very successful collaboration between his and the Halpin group wherein they identified a new branch to the lignin biosynthesis pathway and the associated cse1 Arabidopsis mutant that appears to grow normally.
The Boerjan group has also been involved in an associated piece of research that is an outstanding example of the potential to translate Arabidopsis research into other plants. Following identification of the ccr Arabidopsis mutant, which has less lignin and provides more sugar through saccharification, they generated transgenic poplar trees that had reduced expression of CCR. Subsequent field trials excitingly showed that the amount of sugar released from these plants per volume biomass was improved but unfortunately their overall yield was reduced. However Professor Boerjan also described more recent work in which the Arabidopsis ccr mutant could be rescued by expression of CCR in only xylem elements, allowing the plants to be of normal size but release their sugars more easily. Work is now ongoing to translate this approach into poplar.
The Halpin group are also working on both enhancer and suppressor mutant screens to identify novel regulators of lignin biosynthesis and have discovered some intrigued genetic lesions that are involved in an unexpected biosynthetic pathway. In addition Professor Halpin described a GWAS experiment that her lab has undertaken using 640 barley cultivars. This has identified some novel transcription factors that might be involved in lignin biosynthesis.
Arguably the most exciting result on this topic was provided by Jan Lycakowski from the lab of Paul Dupree who gave a flash talk about his work to characterise a set of Arabidopsis gut triple mutants that are unable to correctly add glucuronic acid (GlcA) to cellulose. These plants have no apparent yield penalty, have normal looking cell walls (thought to be due to the addition of different post-translational modifications instead of GlcA) but yet will release their sugars at a greater rate than wildtype Arabidopsis. It remains to be seen whether this promising result is recapitulated in more industrially relevant plants.
Other talks in the ‘Lignin Construction’ session exemplified that researchers are using many different plant species in order to identify factors that control generation of cell wall biomass. This included examples from hemp (Alexandra Lanot, York), maize (Luisa Trindade, Wageningen), wheat (Kamaljit Moirangthem, Nottingham) and Miscanthus (Ricardo Da Costa, Aberystwyth).
The ‘MS construction’ session largely focused on the role of the sugar xylan in the construction of the cell wall and included a description from Tom Simmons of his attempts to use solid state NMR to resolve the complex structure of the cell wall. In addition Paul Knox (Leeds) gave an update from his labs successful attempts to generate a set of ‘Plant Probes’, antibodies that are specific for motifs within the cell wall. This certainly represents a very useful research tool for interested potential users.
The ‘MS deconstruction’ session included the description of an exciting piece of work by Lenka Frankova who works with Stephen Fry at the University of Edinburgh. From published work, Lenka described the discovery of a unique enzyme, Hetero-trans-B-glucanase (HTG) from Equisetum plants (the ‘living fossil’ species of horsetails). HTG appears to be uniquely able to form crosslinks between cellulose and the MS xyloglucan and therefore offers a potential biochemical mechanism to strengthen cell walls. The Fry group have recently obtained a BBSRC responsive mode grant to investigate the potential role of HTG in a range of grass species. It is intriguing to speculate that this enzyme might provide a novel mechanism to strengthen cell walls, potentially providing an opportunity to add structurally rigidity to existing grass species.
In the ‘Cellulose Construction’ session both Daniel Cosgrove (Penn State) and Simon Turner (Manchester) provided an update on each of their attempts to define the nature of the plant cell wall. The Cosgrove group uses AFM and SEM to determine the arrangement of cellulose microfibrils both in the native state and under strain, the latter experiments using a novel experimental procedure where they physically stress onion epidermal cell walls.
The Turner lab works on the Cellulose Synthase Complex (CSC) and Professor Turner described a set of extremely detailed domain-swap experiments between protein members of the CSC complex. This has allowed them to propose a model for the arrangement of protein subunits within the CSC and offers insight into the mechanism by which this complex is aligned with cellulose and underlying microtubules.
The final ‘plant’ focused talk was provided by Bjorn Sundberg who, following an academic career that helped establish the reputation of the UMEA Plant Science Centre, now also works for the international forestry company StoraEnso. It was fascinating to learn about the companies transition away from paper production into research that focuses on exploiting the energy available in lignocellulose. Professor Sundberg’s role involves the global development of genetic strategies to improve Eucalyptus as a biomass stock. His description of the 20-year timescale from identification of interesting traits to first harvest is something unusual within the timeline of the academic grant cycle! The recently development of a Eucalyptus SNP-chip will hopefully improve this timescale and the company are also looking to improve transformation efficiencies, a bottleneck in the genetic engineering of many crop species.
Elsewhere in the ‘Deconstruction Session’ were talks from invited experts who discussed their work aimed at understanding and improving the process of cell wall breakdown from a microbial perspective. These included studies described by Joe Bennett and Nicola Oates from the University of York where they screened environmental microbial communities that grow on waste grain stalks with the aim of identifying novel degrading enzymes. Nicola in particular described some novel putative carbohydrate-active enzymes isolated from the Graphium species of fungus.
Overall this LBNet meeting provided an outstanding selection of talks and plenty of opportunity for discussion at the remote conference venue of Shrigley Hall, located on the edge of the Peak District. Observationally it seemed that a number of collaborations might arise from discussions. As with each of the BBSRC NIBBs, the LBNet provides ‘Proof of Concept’ and ‘Business Innovation’ funding of up to £50K. Please give some thought how your research might interact with LBNet and contact the network coordinator Vernoica Ongaro.
From a GARNet perspective it was clear from the presented Arabidopsis research that some of the genes involved in cell wall construction would not have been intuitively predicted to act in this process. Therefore it might be worth investigating whether your gene of interest somehow impacts formation of the cell wall as it could open up extra funding opportunities!
Please see this list of live tweets from the conference.
Not logged in