AncPlantDRB1: Ancestral Plant DRB1 is Sufficient to Orchestrate Normal miRNA Biogenesis in Arabidopsis thaliana

We reconstructed the most likely ancestral plant DRB1 protein sequence and transformed Arabidopsis thaliana COL1 to express AncPlantDRB1, rather than the extant DRB1 protein. We measured the effect on miRNA biogenesis using small-RNASeq to quantify levels of annotated A. thaliana miRNAs. We found that knocking out DRB1 had a strong effect on miRNA levels, compared to wild-type, and that AncPlantDRB1 was sufficient to recover near-native miRNA expression. These results suggest that the DRB1-DCL1 interaction required for efficient miRNA biogenesis in A. thaliana arose very early in plant evolutionary history and was largely maintained over millions of years of evolution.