New Route to Lignin Biosynthesis Offers New Opportunity to Improve Biofuels Production
The biosynthetic pathway of lignin, the compound that confers strength and rigidity to plant cell walls and makes their breakdown into biofuels so difficult, is quite complex. Early steps in the pathway are common to the production of a number of different compounds but each path eventually diverges at a specific point. The first step committed to lignin (monolignol) biosynthesis occurs with the enzyme cinnamoyl CoA reductase (CCR). DOE researchers from the Samuel Roberts Noble Foundation have discovered a second, distinct CCR enzyme in a relative of alfalfa, Medicago truncatula, that apparently provides an alternate route to monolignol. This second CCR may give the plant the flexibility to adapt to various developmental conditions. One approach to developing feedstocks with reduced lignin that are easier to deconstruct for biofuel production is to modify genes in the lignin biosynthetic pathway. This new understanding of the lignin biosynthetic pathway will facilitate identification of potential target genes for modification.
Zhou R, Jackson L, Shadle G, Nakashima J, Temple S, Chen F, and Dixon RA. 2010. “Distinct cinnamoyl CoA reductases involved in parallel routes to lignin in Medicago truncatula,” Proc Natl Acad Sci doi:10.1073/pnas.1012900107 (Early Edition, October 7 2010).