Sun Leiqian, Li Peixuan, Cui Xincaiyu, Fan Yawei, Liu Han, Feng YuPing, Li Hui, Lu Hai
State Key Laboratory of Tree Genetics and Breeding, National Engineering Research Center of Tree Breeding and Ecological Restoration, The Tree and Ornamental Plant Breeding and Biotechnology Laboratory of National Forestry and Grassland Administration, College of Biological Sciences and Technology, Beijing Forestry University, Beijing 100083, China.
State Key Laboratory of Tree Genetics and Breeding, National Engineering Research Center of Tree Breeding and Ecological Restoration, The Tree and Ornamental Plant Breeding and Biotechnology Laboratory of National Forestry and Grassland Administration, College of Biological Sciences and Technology, Beijing Forestry University, Beijing 100083, China.
Int J Biol Macromol. 2025 Aug;320(Pt 3):145803. doi: 10.1016/j.ijbiomac.2025.145803. Epub 2025 Jul 11.
Secondary growth is regulated by numerous transcription factors under multi-level transcriptional control; however, only a few are considered as key regulators of secondary cell walls biosynthesis in Populus. This study identified PtoNAC90 as a transcription factor crucial for xylem development in Populus. PtoNAC90 is specifically expressed in developing xylem tissues. Compared to wild-type plants, transgenic Populus lines overexpressing PtoNAC90 display thickened xylem and enhanced secondary cell walls, demonstrating its positive regulatory role in xylem development. Interestingly, the lignin, cellulose, and hemicellulose content in the secondary walls of stem xylem exhibited distinct increases in PtoNAC90-overexpressing plants. Using electrophoretic mobility shift assay (EMSA) and luciferase reporter assays, we demonstrated that PtoNAC90 is directly activated by PtoWND1A. Furthermore, PtoNAC90 directly activates key secondary cell wall deposition genes, including PtoPAL3, PtoCesA6, and PtoCslA9. These findings demonstrate that PtoNAC90 positively regulates secondary cell wall formation and wood development, providing valuable insights into the molecular mechanisms controlling this process in trees.
次生生长受多级转录控制下的众多转录因子调节；然而，在杨树中只有少数转录因子被认为是次生细胞壁生物合成的关键调节因子。本研究鉴定出PtoNAC90是杨树木质部发育的关键转录因子。PtoNAC90在发育中的木质部组织中特异性表达。与野生型植物相比，过表达PtoNAC90的转基因杨树品系木质部增厚，次生细胞壁增强，表明其在木质部发育中具有正向调节作用。有趣的是，在过表达PtoNAC90的植物中，茎木质部次生壁中的木质素、纤维素和半纤维素含量明显增加。通过电泳迁移率变动分析（EMSA）和荧光素酶报告基因分析，我们证明PtoNAC90直接被PtoWND1A激活。此外，PtoNAC90直接激活关键的次生细胞壁沉积基因，包括PtoPAL3、PtoCesA6和PtoCslA9。这些发现表明PtoNAC90正向调节次生细胞壁形成和木材发育，为控制树木这一过程的分子机制提供了有价值的见解。
