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Metabolic engineering of novel lignin in biomass crops

Permanent URL:
http://handle.nal.usda.gov/10113/56463
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Abstract:
Lignin, a phenolic polymer in the secondary wall, is the major cause of lignocellulosic biomass recalcitrance to efficient industrial processing. From an applications perspective, it is desirable that second-generation bioenergy crops have lignin that is readily degraded by chemical pretreatments but still fulfill its biological role in plants. Because plants can tolerate large variations in lignin composition, often without apparent adverse effects, substitution of some fraction of the traditional monolignols by alternative monomers through genetic engineering is a promising strategy to tailor lignin in bioenergy crops. However, successful engineering of lignin incorporating alternative monomers requires knowledge about phenolic metabolism in plants and about the coupling properties of these alternative monomers. Here, we review the current knowledge about lignin biosynthesis and the pathways towards the main phenolic classes. In addition, the minimal requirements are defined for molecules that, upon incorporation into the lignin polymer, make the latter more susceptible to biomass pretreatment. Numerous metabolites made by plants meet these requirements, and several have already been tested as monolignol substitutes in biomimetic systems. Finally, the status of detection and identification of compounds by phenolic profiling is discussed, as phenolic profiling serves in pathway elucidation and for the detection of incorporation of alternative lignin monomers.
Author(s):
Ruben Vanholme , Kris Morreel , Chiarina Darrah , Paula Oyarce , John H. Grabber , Wout Boerjan
Subject(s):
adverse effects , biomass , biosynthesis , energy crops , engineering , genetic engineering , lignin , metabolites , phenolic compounds , processing technology
Source:
New phytologist 2012 v.196 no.4
Language:
English
Year:
2012
Collection:
Journal Articles, USDA Authors, Peer-Reviewed
Rights:
Works produced by employees of the U.S. Government as part of their official duties are not copyrighted within the U.S. The content of this document is not copyrighted.