Seeding the next generation of fuel crops

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For biofuels to become more sustainable, lignocellulosic biomass from trees, grasses and plant stems is an appealing alternative to resource-heavy energy crops such as canola and maize. However, the high lignin content of second generation feedstocks makes them naturally recalcitrant to processing into fuel. While chemical engineers, microbiologists and enzymologists have made strides to overcome these issues, plant biologists are increasingly employed to create fuel crops that will profit the biofuel industry.

Biotechnology for Biofuels is pleased to announce a special thematic series focusing on the development of crops for enhanced fuel production. The series covers genetic improvement of plant biomass traits to increase bio-production and benefit downstream processes such as enzymatic conversion, fermentation, pyrolysis and gasification.

An undesirable trait of woody feedstocks is the abundance of xylan, that cross-links the cellulose fibres in the plant cell wall. Xylan is a polymer of xylose, a sugar that is difficult to ferment and also releases acetate, an inhibitor of fermentation enzymes. Plant biotechnologists have genetically engineered Arabidopsis to lack xylan, however this causes collapse of the xylem vessels, preventing transport of water and nutrients around the plant, resulting in stunted growth. In a highlight of the new series, Petersen et al. have shown how the deleterious effects of the irregular xylem (irx) mutation can be rescued to produce viable plants that retain the desired trait of reduced recalcitrance.

Image credit: Matt Lavin

Our knowledge of plant genomes is a growing resource for the creation of new fuel crops and Feltus and Vandenbrink review the state of genomics and systems biology approaches to identify traits for the improvement of grasses. In another article, Kelsey L Yee et al. study the effects of disrupting the lignin pathway in switchgrass, Panicum virgatum. By knocking out the caffeic acid 3-O-methyltransferase (COMT) gene, more sugar is made available for downstream bacterial conversion to fuel.

The technology to genetically characterize plants and manipulate them via transgenic and selective breeding approaches is well developed. What remains lacking is a shared knowledge of  plant cell wall biochemistry and its interdependence with downstream processing into fuel. Biotechnology for Biofuels will continue to add new publications to this thematic series as they become ready to publish. If you would like to your work to be highlighted here, we have extended the submission deadline to 31 December 2012, so there is still time. Please see the website for more details.