Recent research from Kobe University has unveiled a complex interaction between potatoes, soil microbes, and the notorious potato cyst nematode, opening new avenues for agricultural pest control.

The Threat of Potato Cyst Nematodes

The potato cyst nematode is a root parasite affecting plants like potatoes and tomatoes. These pests can cause significant yield loss, with their eggs capable of surviving in soil for up to 20 years. They hatch in response to specific molecules, known as “hatching factors,” that are secreted by the roots of their host plants. MIZUTANI Masaharu, a scientist in phytochemistry at Kobe University, emphasizes the potential of using these hatching factors as a means of controlling nematode populations. “If we apply hatching factors to agricultural soils prior to planting, we could potentially induce premature hatching of the parasites—a strategy we term ‘suicide hatching’,” he states. However, the identification of these crucial chemicals remains a challenge due to their minimal production.

Unveiling the Chemicals Behind the Interaction

The research team from Kobe University had previously identified two hatching factors, one of which is produced by plants (solanoeclepin B, or SEB), while the other (solanoeclepin A, or SEA) is formed by soil microorganisms. Mizutani and his team found that when tomato root secretions were applied to soil, the concentration of SEB initially increased. This prompted the hypothesis that there must be an unidentified plant-derived molecule that soil microbes transform into SEB and subsequently into SEA.

Discovery of Solanoeclepin C

In a recent publication in the journal New Phytologist, the researchers revealed the identity of the unknown molecule as “solanoeclepin C” (SEC). They found that SEC is secreted by plants in far greater quantities—20 times more than SEB. Interestingly, while SEC itself does not induce hatching of the nematodes, it decomposes in the soil to produce SEB, a process significantly accelerated by microbial action. “This suggests that while SEC serves a physiological role for the plants, it’s through its conversion to SEB and SEA that nematodes get activated,” explains Mizutani. This intricate three-way interaction represents a novel discovery in the realm of plant chemicals.

The Role of Soil Microorganisms

Plants often release chemicals to attract beneficial soil microorganisms that aid in water and nutrient absorption in exchange for carbon-based compounds. Mizutani notes that the secretion pattern of SEC tends to increase, particularly when plants experience nutrient starvation for nitrogen or phosphorus, essential nutrients for plant growth. He suggests that this behavior might indicate an emergency signal to soil microbes, but it also raises the question of whether the nematodes have exploited this process.

Future Directions in Research and Application

Initially, one might perceive hatching factors as strictly detrimental to plants, raising questions about their production. Nonetheless, Mizutani expresses optimism about uncovering the beneficial aspects of these chemicals in forthcoming studies. Regarding the practical application of these findings for pest management, he notes that the structural complexity of these chemicals complicates their synthesis. However, researchers remain determined, hoping that simpler alternatives could replicate the same effects.

This groundbreaking research received funding from the Japan Society for the Promotion of Science and was conducted in collaboration with experts from the RIKEN Center for Sustainable Resource Science, the National Agriculture and Food Research Organization, and Hokkaido University.