The researchers first compared five cytidine deaminases in an Agrobacterium rhizogenes-mediated hairy-root assay. Sdd7 delivered the highest mean editing efficiency, 46.7%, with a low insertion and deletion (InDel) frequency, whereas CDA1 provided a broader editing window. They then strengthened editor expression with the Arabidopsis thaliana ribosomal protein S5A (RPS5A) promoter and tobacco mosaic virus (TMV) Ω enhancer, and co-expressed the human fat mass and obesity-associated gene (hFTO), which encodes a ribonucleic acid (RNA) N6-methyladenosine demethylase, to improve chromatin accessibility. Adding chromatin-modulating peptides (CMPs) derived from high mobility group protein HMGN1 and human histone H1 produced further gains: CDA1-HNHN reached an average efficiency of 80.6%, compared with 25.9% for CDA1, without a significant increase in InDels. The final mini-Sdd7-based editor, RF-Sdd7-HNHN, achieved 65.6%–87.4% editing across three test loci and raised the mean to 76.7%, about 2.9-fold above the unoptimized editor. In stable potato plants, it precisely edited the target residues in both StALS1 and StALS2 in 85.7% of lines, with no off-target changes detected at predicted sites. Edited plants rooted and grew on chlorsulfuron-containing medium and remained healthy after greenhouse spraying, while wild-type controls either failed to root in culture or wilted after spraying.
In explaining the significance of the results, the authors said the advance lies not in a single molecular component, but in combining several complementary improvements into one editing system. Stronger expression increased the amount of editing machinery, while chromatin-focused strategies made target DNA more accessible and helped the editor work more consistently. They said the comparison between Sdd7- and CDA1-based systems also gives researchers a clear choice: a narrower, cleaner editing window for precision breeding, or a broader window for applications such as saturation mutagenesis. This modular approach could make crop genome editing easier to adapt to different biological goals.
The optimized platform could accelerate potato functional genomics, repair harmful alleles that are difficult to separate from useful traits, and support faster development of varieties with improved agronomic performance. Its successful use in herbicide-resistance breeding also suggests a route for coupling acetolactate synthase (ALS) editing with selection of other desired edits, potentially helping researchers recover edited plants more efficiently. Beyond potato, the same design logic may improve adenine base editors, prime editors, and other genome-editing systems in crops with limited editing resources. Before agricultural deployment, however, the approach will require broader testing across potato genotypes, multi-season field evaluation, careful assessment of unintended edits, and consideration of regulatory and stewardship requirements for herbicide-resistant germplasm.
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References
DOI
10.1093/hr/uhag122
Original Source URL
https://doi.org/10.1093/hr/uhag122
Funding information
This study is supported by China National Key Research and Development Program (2023YFF1000400) and China Postdoctoral Science Foundation (2023 M733833).
About Horticulture Research
Horticulture Research is an open access journal of Nanjing Agricultural University and ranked number one in the Horticulture category of the Journal Citation Reports ™ from Clarivate, 2023. The journal is committed to publishing original research articles, reviews, perspectives, comments, correspondence articles and letters to the editor related to all major horticultural plants and disciplines, including biotechnology, breeding, cellular and molecular biology, evolution, genetics, inter-species interactions, physiology, and the origination and domestication of crops.