Creating artificial miR2118a/b to boost yield and broad-spectrum resistance in soybean via CRISPR/Cas9-targeted...

While regulatory functions of mature miRNAs are well established, the functions of miRNAs* and their potential for genetic engineering in crop improvement remain underexplored. Here, we used clustered regularly interspaced short palindromic repeats (CRISPR)/CRISPR-associated protein (Cas9) to generate artificial miR2118a/b (amiR2118a/b) by editing miR2118a/b-5p and obtained several amir2118a/b mutants in soybean (Glycine max). miR2118a/b-5p modifications altered the secondary structure of precursor amiR2118a/b (pre-amiR2118a/b) and reduced mature miR2118a/b levels. These amir2118a/b mutants retained the ability to initiate biogenesis of phased small interfering RNAs (phasiRNAs), albeit with a reduced abundance compared with wild-type (WT) plants. Furthermore, these mutants upregulated the expression of genes related to growth and defense under normal and Pseudomonas syringae pv. glycinea (Psg)-infected conditions, respectively. Notably, two transgene-free amir2118 mutants exhibited enhanced resistance to Psg, soybean cyst nematode (SCN), and root-knot nematode (RKN), and achieved increased yield under pathogen-free field conditions. This study provides a strategy to generate artificial miRNAs (amiRNAs) for crop improvement through the CRISPR/Cas system by mutating miRNAs* in crops.