Long Non-Coding RNA Suppresses Adventitious Root Formation of Poplar by Regulating the Expression of .

Long non-coding RNAs (lncRNAs), a class of poorly conserved transcripts without protein-encoding ability, are widely involved in plant organogenesis and stress responses by mediating the transmission and expression of genetic information at the transcriptional, posttranscriptional, and epigenetic levels. Here, we cloned and characterized a novel lncRNA molecule through sequence alignment, Sanger sequencing, transient expression in protoplasts, and genetic transformation in poplar. is a 215 bp transcript located on poplar chromosome 13, ~50 kbp upstream of on the reverse strand, and the lncRNA may fold into a series of complex stem-loop structures. Despite the small open reading frame (sORF) of 51 bp within , bioinformatics analysis and protoplast transfection revealed that has no protein-coding ability. The overexpression of led to a decrease in the quantity of adventitious roots on the cuttings of transgenic poplars. Further, -regulatory module prediction and CRISPR/Cas9 knockout experiments with poplar protoplasts demonstrated that acts as a negative regulator of adventitious rooting by downregulating the WUSCHEL-related homeobox gene , which is supposed to activate adventitious root development in plants. Collectively, our findings imply that is essential for modulating the formation and development of adventitious roots.