Post-transcriptional regulation dynamics during Eucalyptus globulus tension wood formation

We constructed nine Eucalyptus globulus sRNA libraries from developing xylem of tension and opposite wood collected from trees subjected to mechanical/gravitropic stress. Deep-sequencing of these sRNA libraries allowed the identification of 192 candidate miRNAs. Sequencing analysis of five degradome libraries of developing xylem identified 135 targets for 103 miRNAs, including 38 new ones. The functional classification of the target genes for these newly identified miRNAs highlighted genes related to the secondary cell wall such as those involved in phenylpropanoid and lignin biosynthesis. Two contrasting sets of miRNA and respective targets have been found differentially expressed in between tension and opposite wood. This fundamental knowledge of the post-transcriptional regulation of xylogenesis and cell wall biosynthesis will enable to develop new and more efficient strategies to improve wood biomass for various species of trees.