Leaves from NA wild type and CA knockdown lines treated with the bacterial culture and placed at −3°C, a temperature below which this pathovar is known to nucleate ice (Figure S9A), displayed disease‐like symptoms including water soaking and cell death, whereas infected plants that were not subjected to freezing temperatures displayed non‐freeze‐associated infection symptoms 12 h post infection (Figures 7a,b and S9B‐S9C). This evidence concerns the gene XK and infection.