Monolignols. biosynthesis

Li, L. Popko, J. L. Umezawa, T. Chiang, V. L. 5-Hydroxyconiferyl aldehyde modulates enzymatic methylation for syringyl monolignol formation, a new view of monolignol biosynthesis in angiosperms. J. Biol. Chem. 2000, 275, 6537-6545. 

Chiang VL (2006) Monolignol biosynthesis and genetic engineering of lignin in trees, a review. Environ Chem Lett 4 143-146... 

Figure 4.7 Monolignol biosynthesis. Enzymes involved are cinnamoyl-CoAiNADPH oxidoreductase (CCR (1)), cinnamyl alcohol dehydrogenase (CAD (2)), UDP-glucose cinnamyl alcohol 4-0-glucosyltransferase (3), cinnamyl alcohol 4-0-glucoside glucosidase (4).

Reviews that include aspects of monolignol biosynthesis have been published by, e.g., Lewis and Yamamoto (1990), Davin and Lewis (1992), Whetten and Sederoff (1995), Boudet (1998), Van Rensburg et al. (2000), Dixon et al. (2001), Anterola and Lewis (2002), Boerjan et al. (2003) and Davin and Lewis (2003), Dixon and Reddy (2003), Goujon et al. (2003b), Chiang (2006). 

Anterola, A.M., Jeon, J.Fi., Davin, L.B. and Lewis, N.G. (2002) Transcriptional control of monolignol biosynthesis in Pinus taeda. Factors affecting monolignol ratios and carbon allocation in phenylpropanoid metabolism. /. Biol. Chem., 277, 18272-80. 

Boudet, A.M., Goffner, D., Marque, C. and Grima-Pettenati, J. (1998) Genes involved in the final steps of monolignol biosynthesis and their manipulation for tailoring new lignins. ACS Symp. Ser., 697,65-75. 

Chen, R, Reddy, M.S.S., Temple, S., Jackson, L., Shadle, G. and Dixon, R.A. (2006) Multi-site genetic modulation of monolignol biosynthesis suggests new routes for formation of syringyl lignin and wall-bound ferulic acid in alfalfa Medicago sativa L.). Plant., 48, 113-24. 

Li, L., Cheng, X., Lu, S., Nakatsubo, T, Umezawa, T. and Chiang, V.L. (2005) Clarification of cinnamoyl co-enzyme A reductase catalysis in monolignol biosynthesis of aspen. Plant Cell Physiol, 46, 1073-82. 

The preceding (or first monolignol pathway) methylation step was ultimately discovered to utilize a CoA derivative, that is, caffeoyl CoA (10), to afford the corresponding feruloyl derivative (11), rather than the corresponding cafifeic acid (5) to produce ferulic acid (6). Taken together, these studies had established that two quite distinct biochemical processes were operative for each methylation step in monolignol biosynthesis. 

Li, X., Chappie, C. Understanding lignification challenges beyond monolignols biosynthesis. Plant Physiol. 154, 449-452 (2010)... 

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