Precise base editing of non-allelic acetolactate synthase genes confers sulfonylurea herbicide resistance in maize

The objective of this study was to test the efficiency of targeted C-to-T base editing of two non-allelic acetolactate synthase (ALS) in generating sulfonylurea herbicide-resistant mutants. A CRISPR/Cas9 nickase-cytidine deaminase fused with uracil DNA glycosylase inhibitor (UGI) was employed to achieve targeted conversion of cytosine to thymine in ZmALS1 and ZmALS2. Both protoplasts and recovered mutant plants showed the activity of the cytosine base editor, with an in vivo efficiency of up to 13.8%. Transgene-free edited plants harboring a homozygous 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 chlorsulfuron, a sulfonylurea herbicide widely used in agriculture. Targeted base editing of C-to-T per se and a phenotype verified in the generated mutants demonstrates the power of base editing in precise maize breeding.

Source: The Crop Journal - December 11, 2019 Category: Food Science Source Type: research