The Engineering Research Institute of Agriculture and Forestry, Ludong University, Yantai, China.
State Key Laboratory of Biocatalysis and Enzyme Engineering, School of Life Sciences, Hubei University, Wuhan, China.
J Exp Bot. 2021 Sep 30;72(18):6350-6364. doi: 10.1093/jxb/erab260.
Brassinosteroid-insensitive-1 (BRI1) plays important roles in various signalling pathways controlling plant growth and development. However, the regulatory mechanism of BRI1 in brassinosteroid (BR)-mediated signalling for shoot growth and wood formation in woody plants is largely unknown. In this study, PtBRI1.2, a brassinosteroid-insensitive-1 gene, was overexpressed in poplar. Shoot growth and wood formation of transgenic plants were examined and the regulatory genes involved were verified. PtBRI1.2 was localized to the plasma membrane, with a predominant expression in leaves. Ectopic expression of PtBRI1.2 in Arabidopsis bri1-201 and bri1-5 mutants rescued their retarded-growth phenotype. Overexpression of PtBRI1.2 in poplar promoted shoot growth and wood formation in transgenic plants. Further studies revealed that overexpression of PtBRI1.2 promoted the accumulation of PtBZR1 (BRASSINAZOLE RESISTANT1) in the nucleus, which subsequently activated PtWNDs (WOOD-ASSOCIATED NAC DOMAIN transcription factors) to up-regulate expression of secondary cell wall biosynthesis genes involved in wood formation. Our results suggest that PtBRI1.2 plays a crucial role in regulating shoot growth and wood formation by activating BR signalling.
油菜素内酯不敏感 1 型（BRI1）在控制植物生长和发育的各种信号通路中发挥重要作用。然而，BRI1 在调控木本植物中 shoot 生长和木质部形成的油菜素内酯（BR）信号中的机制在很大程度上尚不清楚。在本研究中，过表达杨树中的油菜素内酯不敏感 1 型基因 PtBRI1.2。检测了转基因植物的 shoot 生长和木质部形成，并验证了涉及的调节基因。PtBRI1.2 定位于质膜，在叶片中表达为主。PtBRI1.2 在拟南芥 bri1-201 和 bri1-5 突变体中的异位表达挽救了其生长迟缓的表型。PtBRI1.2 在杨树中的过表达促进了转基因植物的 shoot 生长和木质部形成。进一步的研究表明，PtBRI1.2 的过表达促进了 PtBZR1（油菜素内酯抗性 1）在核内的积累，进而激活 PtWNDs（木质部相关 NAC 结构域转录因子），上调参与木质部形成的次生细胞壁生物合成基因的表达。我们的结果表明，PtBRI1.2 通过激活 BR 信号在调节 shoot 生长和木质部形成中起着关键作用。
