A potential lncRNA-mRNA association of lncIAA12/IAA12/ARF6.1 in regulating adventitious rooting in Populus

Long non-coding RNAs (lncRNAs) are recognized as important regulators of plant growth, yet their functions in woody species remain poorly characterized. In this study, we identify a novel lncRNA, lncIAA12 , in Populus and investigate its potential role in adventitious root (AR) formation. The full-length 852-nt lncIAA12 transcript was cloned using a stepwise PCR strategy, and its non-coding nature was confirmed through in silico analysis and protoplast-based validation. Expression profiling revealed that lncIAA12 is highly expressed during early AR development. Transgenic poplar overexpressing lncIAA12 exhibited accelerated root initiation, increased root number, and enhanced root elongation; these phenotypes were further promoted by auxin treatment. Our data indicate a close genomic and co-expression relationship between lncIAA12 and its neighboring gene PeIAA12 , suggesting potential cis-regulation. Moreover, computational protein-interaction predictions support a possible association between PeIAA12 and the auxin response factor PeARF6.1, a known positive regulator of AR. Integrating thses observations, we propose a hypothesized regulatory network in which lncIAA12 , PeIAA12, and PeARF6.1 may be coordinately involved in auxin-mediated AR development in poplar. This work provides a testable model for lncRNA function in woody plants and sets the state for future mechanistic studies to validate the proposed interactions and causality within this network. • A novel lncRNA, lncIAA12 , was cloned from Populus . • lncIAA12 overexpression enhances adventitious root initiation and growth. • lncIAA12 upregulates PeIAA12 expression, which activates PeIAA12 to potentiate auxin signaling.