The Engineering Research Institute of Agriculture and Forestry, Ludong University, 186 Hongqizhong Road, Yantai, Shandong 264025, China.
State Key Laboratory of Subtropical Silviculture, Key Laboratory of Modern Silvicultural Technology of Zhejiang Province, Zhejiang A&F University, Hangzhou, Zhejiang 311300, China.
Plant Sci. 2025 Jan;350:112283. doi: 10.1016/j.plantsci.2024.112283. Epub 2024 Oct 11.
Phloem fiber is a key component of phloem tissue and is involved in supporting its structural integrity. NAC domain transcription factors are master switches that regulate secondary cell wall (SCW) biosynthesis in xylem fibers, but the mechanism by which NACs regulate phloem fiber development remains unexplored. Here, a NAC2-like gene in poplar, PagNAC2a, was shown to be involved in phloem fiber differentiation. qRT-PCR and GUS staining revealed that PagNAC2a was specifically expressed in the phloem zone of poplar stems. The overexpression of PagNAC2a in poplar increased plant biomass by increasing plant height, stem diameter, and leaf area. Stem anatomy analysis revealed that overexpression of PagNAC2a resulted in enhanced phloem fiber differentiation and cell wall deposition. In addition, PagNAC2a directly upregulated the expression of PagATL2, a gene involved in phloem development, as revealed by yeast one hybrid (Y1H) and electrophoretic mobility shift assay (EMSA) assays. Overall, we proposed that the PagNAC2a was a positive regulator of phloem fiber development in poplar, and these results provided insights into the molecular mechanisms involved in the differentiation of phloem fibers.
韧皮纤维是韧皮组织的重要组成部分，参与支持其结构完整性。NAC 结构域转录因子是调节木质部纤维次生细胞壁 (SCW) 生物合成的主开关，但 NAC 调节韧皮纤维发育的机制仍未被探索。本研究中，鉴定到杨树中的一个 NAC2 类基因 PagNAC2a 参与韧皮纤维分化。qRT-PCR 和 GUS 染色显示 PagNAC2a 在杨树茎的韧皮区特异性表达。过表达 PagNAC2a 增加了植物生物量，提高了株高、茎直径和叶面积。茎解剖分析显示，过表达 PagNAC2a 导致增强的韧皮纤维分化和细胞壁沉积。此外，酵母单杂交 (Y1H) 和电泳迁移率变动分析 (EMSA) 实验表明，PagNAC2a 直接上调参与韧皮部发育的 PagATL2 基因的表达。总之，我们提出 PagNAC2a 是杨树韧皮纤维发育的正调控因子，这些结果为韧皮纤维分化的分子机制提供了见解。
