Lignin is one of the most valuable renewable industrial materials. To elucidate the mechanism via which lignin is synthesised, we compared the lignin content, leaf hardness, cell wall thickness of palisade tissue, and gene expression patterns of lignin biosynthetic enzymes in three tobacco (Nicotiana tabacum L.) varieties during maturation. The results consistently showed that during maturation, the accumulation of lignin gradually increased in tobacco leaves, reaching a peak at full maturity (45 days after topping), and then gradually decreased. Similarly, the transcript level analysis revealed that the gene expression pattern of NtPAL, NtC4H, NtCCoAOMT and NtCOMT were relatively high, and consistent with the lignin content changes. Thus, the four genes may play regulatory roles in the synthesis of tobacco lignin. Analysis of tissue expression patterns of the lignin synthesis-related gene showed that the NtPAL, NtC4H, Nt4CL, NtHCT, NtCCoAOMT, NtCOMT, NtCCR, NtCAD, and NtPAO were all expressed in stems, roots, and leaves. NtC3H and NtF5H were specifically expressed in stems and roots, and not in leaves. Consistently, the NtC3H promoter induced high GUS expression in stems and petioles, marginal in roots, and no GUS activity in leaves. These results provide insights into molecular regulation of lignin biosynthesis in tobacco.

木质素是最有价值的可再生工业材料之一。为了阐明通过该木质素合成的机制，我们比较了在三个烟草（木质素含量，叶硬度，栅栏组织的细胞壁厚，和基因表达模式的木质素生物合成酶的烟草L.）成熟过程中的品种。结果一致表明，在成熟过程中，木质素的积累在烟叶中逐渐增加，在完全成熟时（摘心后45天）达到峰值，然后逐渐下降。类似地，转录水平分析显示NtPAL，NtC4H，NtCCoAOMT和NtCOMT的基因表达模式相对较高，并与木质素含量变化一致。因此，这四个基因可能在烟草木质素的合成中起调节作用。木质素合成相关基因的组织表达模式分析表明，NtPAL，NtC4H，Nt4CL，NtHCT，NtCCoAOMT，NtCOMT，NtCCR，NtCAD和NtPAO均在茎，根和叶中表达。NtC3H和NtF5H专门在茎和根中表达，而不在叶中表达。一致地，NtC3H启动子诱导了高GUS在茎和叶柄中表达，在根部边缘，叶中没有GUS活性。这些结果提供了对烟草中木质素生物合成的分子调控的见解。