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Abstract

Two major challenges in biology still persist. A large proportion of gene functions remain unknown. And the complexity of regulatory networks is still to be discovered. It is also striking that several examples illustrate that loss of function mutations and gene silencing through RNA interference (RNAi) show great potential for crop improvement. Main concerns with gene silencing have however been simplicity of the procedure, reproducibility and specificity. Artificial microRNAs (miRNAs) present a new and highly specific technology for gene silencing. Based on endogenous rice sequences, we achieved artificial miRNA-directed suppression of the intended target genes in both Nipponbare (japonica) and IR64 (indica). We developed new vectors derived from rice microRNA sequences, and discovered previously unrecognized features important for the design of more effective artificial microRNAs. In addition, we provide a webtool that allows design of artificial microRNAs for a wide variety of monocot crops including maize. This tool incorporates design advances over the original algorithms (http://wmd2.weigelworld.org). This is the first report that artificial miRNAs efficiently trigger gene silencing and mimic mutant phenotypes in monocots. We will discuss how this innovative technology may rapidly offer unexplored ways and great potential for both functional genomics and molecular breeding for inbred and hybrid crops.