Effect of Lc expression on lignin biosynthesis and deposition in wild-type and Lc transgenic sweet potato.
(A) qRT-PCR analysis of the changes in the transcript levels of major lignin biosynthetic genes in the leaves, stems, fibrous roots (S5-S8) and developing storage roots (S16) of 2-month-old wild-type (WT) and Lc transgenic sweet potato. Lc1–3, independent Lc transgenic lines. C4H, cinnamic acid 4-hydroxylase; 4CL, 4-coumarate-CoA ligase; CCoAOMT, caffeoyl-CoA O-methyltransferase; CCR, hydroxycinnamoyl-CoA reductase; CAD, cinnamyl alcohol dehydrogenase; COMT, caffeic acid/5-hydroxyferulic acid O-methyltransferase. (B) Klason lignin contents in the fibrous roots (S5-S8), developing storage roots (S10) and mature storage roots (>S18) of 5-month-old field-grown sweet potato plants. (C) Lignin deposition patterns in the initiating storage roots (S8), early developing storage roots (S10 and S12) and late developing storage roots (S14) of 1.5-month-old plants after staining with two dyes, phloroglucinol-HCl (P-H) and toluidine blue (TB). Error bars represent the SE of three independent replicates. Asterisks indicate a significant difference compared to the WT at *P < 0.05 or **P < 0.01 (t-test).