Plant scientists led by University of Missouri (MU) researchers have found one of the mechanisms that cyst nematodes use to invade and drain life-sustaining nutrients from soybean plants. Cyst nematodes are one of the most economically devastating groups of plant-parasitic nematodes worldwide, damaging root systems and leeching nutrients out of the soybean plant.

Fifteen years ago, Melissa Goellner Mitchum and colleagues at MU unlocked clues into how nematodes use small chains of amino acids, or peptides, to feed on soybean roots. Using next-generation sequencing technologies, the research team in Mitchum's laboratory discovered that nematodes produce a second type of peptide that can effectively "take over" plant stem cells that are used to create vital pathways for the delivery of nutrients throughout the plant. The researchers compared these peptides with those produced by plants and found that they were identical to the ones the plants use to maintain vascular stem cells, known as CLE-B peptides.

The team synthesized the CLE-B nematode peptide and applied it to the vascular cells of Arabidopsis. They found that the nematode peptides triggered a growth response in Arabidopsis much in the same way as the plants' own peptides affected development. When the team "knocked out" the genes Arabidopsis plants use to signal to their own stem cells, the nematodes didn't do as well because the parasites were unable to signal to the plant, and the nematode's feeding site was compromised.

"By knocking out that pathway, we reduced the size of the feeding site that nematodes use to control the plant. This is the first time we've been able to show that the nematode is modulating or controlling the vascular plant pathway," Mitchum said.

For more details, read the news release from the MU News Bureau.

Figure: A nematode, the oblong object on the left, activates the vascular stem cell pathway in the developing nematode feeding site, or the syncytium, on a plant root. Credit: Xiaoli Guo