Pyrolysis mass spectral characterization of wood from CAD-deficient pine

An extremely low level of the cinnamyl alcohol dehydrogenase (CAD) enzyme activity in a mutant loblolly pine tree leads to a different pool of precursors for lignin production. Characterization of CAD-deficient wood by pyrolysis mass spectroscopy indicates significant increased levels of dihydroconiferyl alcohol, not usually considered a lignin subunit. Also, in comparison to normal pine lignin, the CAD-deficient lignin has increased levels of coniferaldehyde, the substrate of CAD, and of p-coumaryl alcohol, along with greatly decreased levels of coniferyl alcohol. These findings are consistent with trees of different ages and confirm that there is considerable plasticity in the biosynthesis of lignin. Trees are able to utilize structures beyond the traditional definition of precursors to make lignin.