Fig. 7

Engineering altered lignin composition in M. truncatula hairy roots by down-regulation of COMT and HCT, and overexpression of Selaginella moellendorffii F5H (SmF5H) and Cleome hassleriana CAD5 (ChCAD5). A Scheme showing the predicted pathway. B–G Monolignol content and composition of selected lines. (B) Total lignin thioacidolysis yields; (C) overall % lignin monomer compositions; (D) % of H-lignin monomers; (E) % of C-lignin monomers; (F) % of G-lignin monomers; (G) % of S-lignin monomers. Hairy root lines designated OR(h) are engineered lines for SmF5H/ChCAD5-OX and HCT/COMT RNAi in the comt mutant background. Subsequent genotyping led to selection of plants with no transgenes (−/−), RNAi but not OX transgene (−/+), OX but no RNAi transgene (±), and the presence of both transgenes (+/+). Wild-type R108 and comt mutant, both transformed with GUS, served as additional negative controls, and wild-type stems were included for comparison. Transgene constructs are shown in Additional file 1: Fig. S2, and transcript levels of the targeted genes in each line shown in Additional file 1: Fig. S8. FAHC, transformed with overexpression construct for SmF5H (F) and ChCAD5 (A) and RNAi construct for MtHCT (H) and MtCOMT (C). Data are means ± SD derived from three biological replicates