Modifying lignin to improve bioenergy feedstocks: strengthening the barrier against pathogens?

Authors: Sattler, Scott; Funnell-Harris, Deanna

Submitted to: Frontiers in Plant Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/14/2013
Publication Date: 4/5/2013
Publication URL: https://handle.nal.usda.gov/10113/56310
Citation: Sattler, S.E., Funnell-Harris, D.L. 2013. Modifying lignin to improve bioenergy feedstocks: strengthening the barrier against pathogens? Frontiers in Plant Science. 4: 70. DOI 10.3389/fpls.2013.00070

Interpretive Summary: Lignin is a component of plants cell walls, where it strengthens and stiffens the cell wall structure. However, the presence of lignin within plant cell walls makes the biomass more difficult to convert into biofuels. Therefore, reducing lignin has become a major goal to improve crop plants for bioenergy uses. In addition, plants also make lignin in the cell walls to defend themselves against disease-causing fungi and bacteria. This article explores the impact of changing the amount of lignin in plant cell wall on their ability defend themselves against diseases, and the implications for developing new plant varieties for the biofuels industry. Surprisingly, plants with a reduced amount of lignin may be more resistant to some disease-causing fungi. Potential reasons for this unexpected result are also examined in this article.

Technical Abstract: Lignin is a ubiquitous polymer present in cell walls of all vascular plants, where it rigidifies and strengthens the cell wall structure through covalent cross-linkages to cell wall polysaccharides. The presence of lignin makes the cell wall recalcitrant to conversion into fermentable sugars for bioenergy uses. Therefore, reducing lignin content and modifying its linkages have become major targets for bioenergy feedstock development through either biotechnology or traditional plant breeding. In addition, lignin synthesis has long been implicated as an important plant defense mechanism against pathogens, because lignin synthesis is often induced at the site of pathogen attack. This article explores the impact of lignin modifications have on the susceptibility of a range of plant species to their associated pathogens, and the implications for development of feedstocks for the second-generation biofuels industry. Surprisingly, most preliminary data suggest that plants modified in lignin synthesis may display improved resistance to their associated pathogens, which is explored in this article.