by Lauren Quinn, University of Illinois at Urbana-Champaign
When we think of evolution, many of us conjure the lineage from ape to man, a series of incremental changes spanning millions of years. But in some species, evolution happens so quickly we can watch it in real time.
That's the case for Xanthomonas, the organism that causes bacterial leaf spot disease in tomato and pepper plants. Like many microbes with short generation times, it can evolve at lightning speed to acquire beneficial traits, such as the ability to elude its host's defense system.
New research from the University of Illinois shows one Xanthomonas species, X. euvesicatoria (Xe), has evolved to avoid detection by the immune system of tomato plants.
"It's part of the evolutionary warfare between plants and pathogens, where the plant has some defense trait and then some portion of the pathogen population evolves to escape it. The plant has to develop or acquire a new defense trait, but the process is much slower in plants compared to microbes. This study is a great example of that ongoing battle in progress. It tells us we can't completely rely on this trait to combat bacterial spot disease caused by Xe," says Sarah Hind, assistant professor in the Department of Crop Sciences at Illinois and co-author on a pair of recent studies published in Molecular Plant-Microbe Interactions and Physiological and Molecular Plant Pathology.