Design of a bacterial speck resistant tomato by CRISPR/Cas9‐mediated editing of SlJAZ2

Due to their different lifestyles, effective defence against biotrophic pathogens normally leads to increased susceptibility to necrotrophs, and vice versa. Solving this trade‐off is a major challenge for obtaining broad‐spectrum resistance in crops and requires uncoupling the antagonism between the jasmonate (JA) and salicylate (SA) defence pathways. Pseudomonas syringae pv. tomato (Pto) DC3000, the causal agent of tomato bacterial speck disease, produces coronatine (COR) that stimulates stomata opening and facilitates bacterial leaf colonization. In Arabidopsis, stomata response to COR requires the COR co‐receptor AtJAZ2, and dominant AtJAZ2Δjas repressors resistant to proteasomal degradation prevent stomatal opening by COR. Here, we report the generation of a tomato variety resistant to the bacterial speck disease caused by Pto DC3000 without compromising resistance to necrotrophs. We identified the functional ortholog of AtJAZ2 in tomato, found that preferentially accumulates in stomata and proved that SlJAZ2 is a major co‐receptor of COR in stomatal guard cells. SlJAZ2 was edited using CRISPR/Cas9 to generate dominant JAZ2 repressors lacking the C‐terminal Jas domain (SlJAZ2Δjas). SlJAZ2Δjas prevented stomatal reopening by COR and provided resistance to Pto DC3000. Water transpiration rate and resistance to the necrotrophic fungal pathogen Botrytis cinerea, causal agent of the tomato gray mold, remained unaltered in Sljaz2Δjas plants. Our results solve the defence trade‐off in a crop, by spatially uncoupling the SA‐JA hormonal antagonism at the stomata, entry gates of specific microbes such as Pto DC3000. Moreover, our results also constitute a novel CRISPR/Cas‐based strategy for crop protection that could be readily implemented in the field.