Plant Pathogens

A UNC-Chapel Hill interdisciplinary research team of chemists and biologists has unlocked an important clue in understanding how plant pathogens cause diseases that can create significant crop damage worldwide.

The bacterial species Pseudomonas syringae can infect over 50 different species of plants, including bean, wheat, rice, cabbage, tomato, beet and more. The study utilized two model plants, Arabidopsis thaliana, thale cress, and Nicotiana benthamiana, a tobacco relative, that can also be infected by this bacterial pathogen.

Scientific diagram

The team, led by Carolina Chemistry assistant professor Bo Li, and Jeff Dangl, HHMI Investigator and John N. Couch Professor of Biology in UNC’s College of Arts & Sciences, wanted to understand how pathogenic bacteria can impair plant defense and promote infection.

They identified a new small molecule called phevamine A that has a very different structure from other known bacterial toxins. Rather than damaging the plant cell, it suppresses several tested plant defense mechanisms, which gives the pathogen the opportunity to grow and cause infection.

Small molecules are organic compounds produced by bacteria using designated enzymes for a specific function. For example, some small molecules help defend the bacteria against competitors, i.e. antibiotics. Other small molecules enable the bacteria to mount attack on host cells, like phevamine A, according to Li.