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The removal of lignin in paper manufacture is a toxic and energy-requiring process. For the paper industry and for the environment, it would be very beneficial to process trees with less lignin or with lignin that is more easily ex tractable. To achieve this goal, we are down-regulating the activity of a number of lignin biosynthesis enzymes in poplar by genetic engineering and studying their role in determining the quantity and quality of lignin. Here, our recent results obtained in this field are summarized with emphasis on bispecific caffeic acid/5-OH-ferulic acid-O-methyltransferase, cinnamoyl-CoA-reductase, caffeoyl-CoA-O-methyltransferase, and peroxidase.

Extractive-free wheat straw, and the corresponding samples issued from its alkaline treatment — i.e. saponified wheat straw and alkali-soluble wheat lignin- were submitted to three chemical procedures of lignin characterization: nitrobenzene oxidation, acidolysis and thioacidolysis. The various performances of the three techniques were comparatively evaluated. The thioacidolysis procedure was found to have higher performances with regards to the two following criteria: the prominent alkyl aryl ether lignin structures were the almost exclusive source for the recovered degradation products; these products were obtained with a high yield. These advantages make the thioacidolysis procedure an unambiguous way to characterize grass lignins, even when present in low amounts.