This shows hydrogen peroxide nanobursts when a plant is wounded. Normally, hydrogen peroxide is kept at low levels when plants grow, and it forms localized dark-blue spots at tiny cellular bridges called plasmodesmata (left). These nanobridges are already fired up brightly with hydrogen peroxide in wounded tissue (right) when the image was taken shortly after the plant was wounded. It shows an almost immediate chemical response to a plant’s injury. The nanobursts are visualized using a fluorescent sensor that the paper’s authors developed. (Courtesy Jung-Youn Lee)