Chen Hao, Li Chenhe, Xu Tingting, Du Kang, Yang Jun, Kang Xiangyang
State Key Laboratory of Tree Genetics and Breeding, Beijing Forestry University, Beijing 100083, China; National Engineering Research Center of Tree Breeding and Ecological Restoration, College of Biological Sciences and Technology, Beijing Forestry University, Beijing 100083, China.
State Key Laboratory of Tree Genetics and Breeding, Beijing Forestry University, Beijing 100083, China; National Engineering Research Center of Tree Breeding and Ecological Restoration, College of Biological Sciences and Technology, Beijing Forestry University, Beijing 100083, China.
Int J Biol Macromol. 2025 Jan;284(Pt 1):138041. doi: 10.1016/j.ijbiomac.2024.138041. Epub 2024 Nov 23.
Lignin is a crucial constituent of cell walls and plays a pivotal role in plant growth and development. However, the transcriptional regulatory network governing lignin biosynthesis is not fully understood. In this study, we observed that PpnCCT39 overexpression resulted in greener stems, larger basal diameters, and increased stem dry weight. Additionally, the secondary xylem of lines overexpressing PpnCCT39 was wider, had larger xylem fiber cell areas, and thicker cell walls, compared to those of wild-type plants. Furthermore, PpnCCT39 overexpression led to elevated lignin content and enhanced the rigidity of secondary cell walls. RNA-seq and ChIP-seq association analyses identified 826 potential regulatory target genes of PpnCCT39 that were upregulated and expressed in 1-month-old PpnCCT39 overexpression lines. Gene enrichment analyses revealed enrichment in pathways related to cell wall formation, xylem and phloem development, and the phenylpropanoid pathway. Two genes involved in lignin biosynthesis, PagCOMT1 and PagBGLU18-2, exhibited significantly increased expression in stems of lines overexpressing PpnCCT39, as demonstrated by high FPKM values and RT-qPCR results. Further investigations using yeast one-hybrid, dual-luciferase assays, and electrophoretic mobility shift assays demonstrated that PpnCCT39 directly activates the transcription of PagCOMT1 and PagBGLU18-2, thereby promoting lignin biosynthesis. This study elucidated the transcriptional regulatory mechanism of PpnCCT39 in poplars and revealed its role in activating the expression of key lignin biosynthesis genes. PpnCCT39 facilitates lignin biosynthesis and secondary growth processes, offering a novel theoretical framework for modulating lignin biosynthesis and enhancing timber yield through molecular design.
木质素是细胞壁的重要组成部分，在植物生长发育中起关键作用。然而，调控木质素生物合成的转录调控网络尚未完全明晰。在本研究中，我们观察到过表达PpnCCT39导致茎更绿、基部直径更大且茎干重增加。此外，与野生型植株相比，过表达PpnCCT39的株系次生木质部更宽，木质部纤维细胞面积更大且细胞壁更厚。再者，过表达PpnCCT39导致木质素含量升高并增强了次生细胞壁的刚性。RNA测序和染色质免疫沉淀测序关联分析确定了826个PpnCCT39潜在调控靶基因，这些基因在1月龄过表达PpnCCT39的株系中上调并表达。基因富集分析显示在与细胞壁形成、木质部和韧皮部发育以及苯丙烷途径相关的通路中富集。参与木质素生物合成的两个基因PagCOMT1和PagBGLU18 - 2，在过表达PpnCCT39的株系茎中表现出显著增加的表达，高FPKM值和RT - qPCR结果证明了这一点。使用酵母单杂交、双荧光素酶测定和电泳迁移率变动分析的进一步研究表明，PpnCCT39直接激活PagCOMT1和PagBGLU18 - 2的转录，从而促进木质素生物合成。本研究阐明了杨树中PpnCCT39的转录调控机制，并揭示了其在激活关键木质素生物合成基因表达中的作用。PpnCCT39促进木质素生物合成和次生生长过程，为通过分子设计调控木质素生物合成和提高木材产量提供了新的理论框架。
