Figure 9.

Incorporation of Exogenous Caffeyl Alcohol into Lignin in Arabidopsis-Expressing ChLAC8.

(A) to (C) Lignin monomer thioacidolysis yields for hydroxyphenyl (A), caffeyl (B), and guaiacyl (C) units. The yields for 5-hydroxyguaiacyl and syringyl units were under the limit of quantification. Values shown are percentages of total lignin units in stem tissues.

(D) Percentage incorporation of ¹³C₆-caffeyl alcohol into caffeyl units. No labeled guaiacyl, 5-hydroxyguaiacyl, or syringyl units were detected.

Cut stems were incubated with 100 μM of ¹³C6-caffeyl alcohol for 2 d before extraction of lignin and analysis by thioacidolysis. Four independent lines expressing ChLAC8 (L) were analyzed and compared with two lines expressing GUS (G), all in the comt mutant background. For each biological replicate, five stem fragments were harvested. Data for lignin composition are means of three biological replicates (after averaging two analytical replicates). Error bars indicate ses. The different letters above the bars represent statistically significant differences determined by one-way ANOVA (Duncan, P ≤ 0.05) with the software SPSS Statistics (v22; IBM).