The Guava Root-Knot Nematode (Meloidogyne enterolobii) is an emergent plant pathogen that has devastated farmers around the world, with some tomato growers reporting up to 65% in yield losses. This nematode has a wide host range from vegetables to fruit trees, and chemical nematicides can be costly and damaging to the environment. However, what if the secret to its control lies in the microscopic life beneath our feet?
The way farmers manage their soil can determine plant health and productivity, but what if soil management also influences the presence of Guava Root-Knot Nematodes (GRKN) and the microscopic life in the soil? In a recent study, a group of researchers assessed the impact of soil management on GRKN infections, tomato plant health, and the soil bacterial microbiome.
The experiment was conducted in a greenhouse, with tomatoes planted in pots with soil collected from either a native or an agricultural field. Different inoculums were applied, and the project was replicated the following year. The experiment in Year 2 was replicated with identical conditions, except the native soil had a cover crop, Bahia grass (Paspalum notatum), planted between years. Researchers discovered that the Year 2 experiment had an increase in plant health, decrease in nematode infection, and a shift in the relative microbial abundances. Plant health was assessed in Year 1 and Year 2, and we found an increase in root fresh weight (56%), shoot fresh weight (82%), and fruit fresh weight (76%) in Year 2. In addition to healthier tomato plants, the experiment in Year 2 showed a staggering 80% decrease in nematode eggs in comparison to Year 1.
These improvements in plant health and lessened infection were accompanied by a shift in the bacteria in the soil. The abundances changed for most of the top phyla (eg. Actinobacteria, Bacteroidetes, and Chloroflexi, see figure 1B) and genera (eg. Bacillus, Streptomyces, and Flavisolibacter, see figure 2B).
Josephine M. Pasche, Janete A. Brito, Gary E. Vallad, Jeremy Brawner, Samantha L. Snyder, Ellen A. Fleming, Jingya Yang, Willian C. Terra and Samuel J. Martins published this study in Plant Pathology:
TITLE IMAGE: Galls caused by the GRKN (M. enterolobii) in tomato. All images used with permission of the author.