Liu Ying-Li, Song Xue-Qin, He Hui, Hu Meng-Xuan, Lu Meng-Zhu, Zhao Shu-Tang
State Key Laboratory of Tree Genetics and Breeding, Chinese Academy of Forestry, Beijing 100091, China.
State Key Laboratory of Tree Genetics and Breeding, Research Institute of Forestry, Chinese Academy of Forestry, Beijing 100091, China.
For Res (Fayettev). 2025 Aug 29;5:e018. doi: 10.48130/forres-0025-0018. eCollection 2025.
Adventitious root formation is a crucial developmental process in the clonal propagation of economically significant horticultural and woody species. This process is antagonistically regulated by auxin and cytokinin, yet the underlying molecular regulatory mechanisms remain poorly understood. In this study, we investigated the role of , a homolog of auxin response factor 3, in hybrid poplar ( × clone cv. '84K'), focusing on its involvement in adventitious root formation. GUS staining analysis revealed that was expressed in adventitious root tips, pericycle cells, early root primordia, and outgrowing roots. Knockdown of delayed adventitious root formation and reduced root biomass in transgenic plants, whereas overexpression of promoted earlier rooting and increased the number of adventitious roots. Real-time quantitative polymerase chain reaction analysis indicated that the expression levels of and were significantly elevated in RNAi lines and reduced in overexpression lines. Yeast one-hybrid assays and ChIP-PCR analysis demonstrated that PagARF3.1 directly binds to the promoter regions of and , thereby regulating their expression. These findings collectively demonstrate that PagARF3.1 acts as a positive regulator of adventitious root formation by repressing IPT-mediated cytokinin biosynthesis.
不定根形成是经济价值显著的园艺和木本植物克隆繁殖中的一个关键发育过程。这一过程受到生长素和细胞分裂素的拮抗调节，但其潜在的分子调控机制仍知之甚少。在本研究中，我们研究了生长素响应因子3的同源物PagARF3.1在杂交杨树（× 无性系cv. '84K'）中的作用，重点关注其在不定根形成中的参与情况。GUS染色分析表明，PagARF3.1在不定根根尖、中柱鞘细胞、早期根原基和生长中的根中表达。抑制PagARF3.1会延迟转基因植物的不定根形成并降低根生物量，而PagARF3.1的过表达则促进更早生根并增加不定根数量。实时定量聚合酶链反应分析表明，PagIPT7和PagIPT8的表达水平在PagARF3.1 RNA干扰系中显著升高，而在过表达系中降低。酵母单杂交试验和染色质免疫沉淀PCR分析表明，PagARF3.1直接结合PagIPT7和PagIPT8的启动子区域，从而调节它们的表达。这些发现共同表明，PagARF3.1通过抑制IPT介导的细胞分裂素生物合成，作为不定根形成的正调控因子。
