Lignin was assayed quantitatively by derivatization with thioglycolic
acid from cell wall materials. Five mL of 2 M HCI and 0.5 mL
of thioglycolic acid were added to 40 mg of CWM in glass screw cap
tubes. The detailed procedure was described by Bruce and West
(1989)
. The final orange-brown pellets were dissolved in 15 mL of
0.5 M NaOH, and the absorbance (A) at 280 nm was measured.