Researchers at the University of Tsukuba have discovered a way to protect cabbage and oat leaves from bacterial infection using multiple amino acids. The bacterium Pseudomonas cannabina pv. alisalensis (Pcal) causes significant damage to these crops, and current treatments such as copper-containing fungicides and antibiotics are becoming less effective due to resistant strains of the bacterium. The team found that treating the leaves with amino acids reduced the bacterial population and disease symptoms when the pathogen was sprayed onto the leaves. This is believed to be due to a decrease in the size of the stomatal opening, which reduces the penetration of bacteria into the plants.