[7][2][1] Exposure to light can trigger photosynthesis in plant leaves, such as leafy-greens, and increase concentrations of photosynthetic products, such as glucose, within the leaf tissue.
[8] Several bacteria, such as Escherichia coli and Salmonella enterica, are able to attach the microstructure at the surface of plant leaves, such as trichomes, stomata and grooves,[9] and localize at sites that are not accessible for wash water and sanitizers.
Incubation of S. enterica (serovar Typhimurium) on iceberg lettuce leaves in the light led to association of bacteria near open stomata and infiltration into the leaf tissue.
[12] Opening of the stomata in light brings up an opportunity for bacteria to transport via chemotaxis toward the gradients of nutrients into the leaf interior.
Many plants have evolved stomatal defense machinery to close the stomata upon perception of bacterial surface structures, known as microbe-associated molecular patterns (MAMPs).