Abstract
The present protocol to visualize living bacteria at the pore level of cauliflower hydathodes is simple and trained users in confocal microscopy can execute it successfully. It can be easily adapted to capture images with other plant-microorganism interactions at the leaf surface and should be useful to obtain important information on pore and stomatal biology. A critical limitation to methods used to observe plant-microorganism interactions in the pore is the application of too much pressure to the sample during observations and z-stack acquisitions. To solve this issue, we recommend the use of a long working-distance water immersion objective lens that allows observations even with thick samples.