A defense-inducible bidirectional promoter enables disease-resistance engineering in Arabidopsis without growth trade-offs

The defense-growth trade-off remains a central challenge in crop breeding. For molecular breeding of crop disease resistance, immune-inducible promoters are valuable tools, as constitutive expression of defense-related genes often leads to growth defects. In this study, through transcriptome analysis and reporter-based screening, we identified BiPro1, a compact (313 bp) defense-inducible bidirectional promoter from Arabidopsis thaliana, which is responsive to elicitors such as the bacterial flagellin peptide flg22 and fungal chitin oligosaccharides. To demonstrate its utility, we used BiPro1 to precisely replace the intergenic region between two head-to-head nucleotide-binding leucine-rich repeat (NLR) genes, RRS1 and RPS4, via CRISPR/Cas9-mediated homologous recombination (HR). The HR-edited plants exhibited normal growth under unchallenged conditions but displayed markedly enhanced induction of both RRS1 and RPS4 under elicitor treatment, accompanied by significantly elevated immune responses. This endowed BiPro1 knock-in plants with broad-spectrum resistance to both bacterial and fungal pathogens, including Pseudomonas syringae, Ralstonia solanacearum, Botrytis cinerea, and Verticillium dahliae. These findings establish BiPro1 as a useful regulatory switch for disease resistance engineering in plants and provide an NLR-based strategy to generate crops with enhanced disease resistance while minimizing growth penalties.