An in vivo Transient Expression System Can Be Applied for Rapid and Effective Selection of Artificial MicroRNA Constructs for Plant Stable Genetic Transformation

The utility of artificial microRNAs (amiRNAs) to induce loss of gene function has been reported for many plant species, but expression efficiency of the different amiRNA constructs in different transgenic plants was less predictable. In this study, expressions of amiRNAs through the gene backbone of Arabidopsis miR168a were examined by both Agrobacterium-mediated transient expression and stable plant genetic transformation. A corresponding trend in expression of amiRNAs by the same amiRNA constructs between the transient and the stable expression systems was observed in the experiments. Plant genetic transformation of the constructs that were highly expressible in amiRNAs in the transient agro-infiltration assays resulted in generation of transgenic lines with high level of amiRNAs. This provides a simple method for rapid and effective selection of amiRNA constructs used for a time-consuming genetic transformation in plants.