Identification of birch lncRNAs and mRNAs responding to salt stress and characterization of functions of lncRNA


 Long noncoding RNAs (lncRNAs) are important in abiotic stress tolerance. Here, we identified salt-responsive genes and lncRNAs in the roots and leaves of Betula platyphylla Suk. (birch), and characterized their lncRNAs functions. In total, 2660 mRNAs and 539 lncRNAs responding to salt treatment were identified using RNA-seq. The salt-responsive genes were substantially enriched in both “cell wall biogenesis” and “wood development” in the roots and were enriched in “photosynthesis” and “response to stimulus” in the leaves. Meanwhile, the potential target genes of the salt-responsive lncRNAs in roots and leaves were both enriched in “nitrogen compound metabolic process” and “response to stimulus”. We further built a method for quickly identifying abiotic stress tolerance of lncRNAs, which employed transient transformation for overexpression and knock-down of the gene, enabling gain- and loss-of-function analysis. Using this method, 11 randomly selected salt-responsive lncRNAs were characterized. Among them, 6 lncRNAs confer salt tolerance, 2 lncRNAs confer salt sensitivity, and the other 3 lncRNAs are not involved in salt tolerance. In addition, a lncRNA, LncY1, was further characterized, which improves salt tolerance by regulating two transcription factors, BpMYB96 and BpCDF3. Taken together, lncRNAs play important roles in the salt response of birch plants.