RESEARCHERS from Chinese Academy of Agricultural Sciences and other institutions reported precise based editing of maize genes using CRISPR-Cas9, leading to development of sulfonylurea herbicide resistance. The results are published in The Crop Journal.
A CRISPR-Cas9 nickase-cytidine deaminase fused with uracil DNA glycosylase inhibitor was used for targeted conversion of cytosine (C) to thymine (T) in two non-allelic acetolactate synthase genes (ZmALS1 and ZmALS2) to generate sulfonylurea herbicide resistant mutants. The results showed that both protoplasts and recovered mutant plants exhibited the activity of the cytosine base editor. Transgene-free edited plant with ZmALS1 mutation or a ZmALS1 and ZmALS2 double mutation were tested for their resistance at a dose of up to 15-fold the recommended limit of sulfonylurea herbicide.
Based on the results, the confirmed targeted base editing in maize plants exhibiting herbicide resistance could be a potential technique in precision breeding of maize.