Lignin remains one of the most significant barriers to the efficient utilization of lignocellulosic substrates, in processes ranging from ruminant digestibility to industrial pulping, and in the current focus on biofuels production. Lignification is, however, a remarkably metabolically plastic process. A few approaches toward altering the composition and structure of lignin (and, therefore, its reactivity) hold considerable promise for reducing the severity and energy demands of industrial processes. Researchers are now contemplating actually <i>designing</i> lignins, by introducing novel phenolic monomers into the plant lignification process, to improve the ease with which the resulting lignins can be removed from the cell wall. One such method, via the so-called ‘zip-lignin’ approach, is showing particular promise. Poplar trees have already been engineered to incorporate monolignol ferulate conjugates into the lignification process, resulting in the introduction of readily cleavable ester linkages into the backbone of the polymer, and portending significantly improved processing. We shall describe the advances, including getting the monolignol ferulate conjugates into grasses, in which we were concerned that the natural <i>p</i>-coumaroylation of monolignols might compete. In addition, now that we have sensitive methods for determining if/when/whether plants are making monolignol ferulate conjugates and using them for lignification (methods that have not previously been available!), it appears that Nature herself may have in fact already been exploring this avenue. We’ll provide insight into the plants that seem to be doing this and try to elucidate how they are, or are not, doing it. [The question of why is likely to require a lot more time, research, and insight].

Update on Zip-lignins™: Lignins designed for deconstruction

249th National Meeting (2015)

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