Key Laboratory for Cultivation of Tobacco Industry, College of Tobacco Science, Henan Agricultural University, Zhengzhou 450002, China.
China Tobacco Chongqing Industrial Co., Ltd, Chongqing 400715, China.
Funct Plant Biol. 2021 May;48(6):624-633. doi: 10.1071/FP20244.
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。为了阐明木质素合成的机制，我们比较了三个烟草品种（Nicotiana tabacum L.）在成熟过程中木质素含量、叶片硬度、栅栏组织细胞壁厚度和木质素生物合成酶基因的表达模式。结果一致表明，在成熟过程中，烟草叶片中的木质素逐渐积累，在完全成熟（打顶后 45 天）时达到峰值，然后逐渐减少。同样，转录水平分析表明，NtPAL、NtC4H、NtCCoAOMT 和 NtCOMT 的基因表达模式较高，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合成中发挥调节作用。对木质素合成相关基因的组织表达模式进行分析表明，NtPAL、NtC4H、Nt4CL、NtHCT、NtCCoAOMT、NtCOMT、NtCCR、NtCAD 和 NtPAO 均在茎、根和叶中表达。NtC3H 和 NtF5H 特异性地在茎和根中表达，而不在叶中表达。同样，NtC3H 启动子在茎和叶柄中诱导高 GUS 表达，在根中呈边缘表达，在叶中无 GUS 活性。这些结果为烟草木质素生物合成的分子调控提供了线索。
