Overexpression of the long non-coding RNA lncWOX5 negatively regulates the development of adventitious roots in Populus

Adventitious root (AR) development plays an essential role in the vegetative propagation of important trees and is an inheritable quantitative trait controlled by a variety of endogenous and environmental factors. Long noncoding RNAs (lncRNAs) are crucial factors during plant development and environmental responses. Large members of lncRNAs have been predicted in woody plants in recent years, but their authenticity and biological functions have rarely been reported. In this study, the lncRNA-lncWOX5, which is involved in poplar root development was cloned from hybrid poplar. The length of lncWOX5 was 432 bp, and it was predicted to have a 75 bp small open reading frame (sORF). Bioinformatics analysis and the detection of transient expression revealed that lncWOX5 has no protein coding ability. LncWOX5 was mainly expressed in the roots, indicating an obvious tissue-specific pattern. The phenotypic analysis showed that overexpression of lncWOX5 (OE_lncWOX5) inhibited AR formation in poplar by regulating the expression of the potential target gene PeWOX5a. Moreover, under NAA treatment, the expression of the potential target gene PeWOX5a in transgenic poplar gradually increased to the original levels as in the WT. Altogether, these results suggest that lncWOX5 plays an essential role in mediating AR formation and development in poplar.