Generation of a high-efficiency adenine base editor with TadA8e for developing wheat dinitroaniline-resistant germplasm

Base editing using CRISPR technologies is an invaluable tool for crop breeding. One of the major base editors, the adenine base editor (ABE), has been successfully used in both model plants and many crops. However, owing to limited editing efficiency, the ABE has been difficult to apply in polyploid crops such as allohexaploid bread wheat that often require simultaneous mutation of multiple alleles for fast breeding. We have designed a wheat high-efficiency ABE (WhieABE), using the newly developed high-activity adenosine deaminase TadA8e. In vivo and in vitro analysis demonstrated the improved applicability of TadA8e over the commonly used TadA7.10. Dinitroaniline is a widely used herbicide with high effectiveness and low toxicity to animals. However, wheat cultivars with tolerance to dinitroaniline are rare, limiting the application of dinitroaniline in wheat planting. Using A-to-G editing with WhieABE, we found that a Met-to-Thr mutation in wheat tubulin alleles located on chromosomes 1A, 1B, 1D, 4A, and 4D increased the resistance of wheat to dinitroaniline, revealing a dosage effect of edited tubulins in resistance. The WhieABE promises to be a valuable editing tool for accelerating crop improvement and developing herbicide-resistant wheat germplasm.