Nematode pheromone prepares plants against pathogens

Researchers have demonstrated the potential of ascaroside ascr#18, a pheromone produced by soil nematodes, to prepare the immune system of plants against different pathogens. The compound promoted prolonged resistance without permanently activating defenses, a process associated with lower growth and development costs.

The mechanism involves what is called immune priming. After contact with ascr#18, regulatory regions of defense genes exhibit more open chromatin. This condition facilitates a faster response after infection. In Arabidopsis thaliana, activation depended on the NILR1 receptor. Mutant plants lacking proper function of this receptor lost the priming effect promoted by the compound.

Seed treatment also maintained its effect for several weeks. In soybeans, it increased survival after inoculation with Phytophthora sojae and reduced the systemic spread of soybean mosaic virus. In wheat, the treatment suppressed between 80% and 90% of Rhizoctonia solani multiplication. Treated rice also showed less damage after inoculation with Xanthomonas oryzae.

Field trials expanded the results. In corn, foliar application of 25 milligrams per acre reduced the severity of leaf spot caused by Bipolaris maydis and increased productivity. In soybeans, two applications of 50 milligrams per acre reduced Asian soybean rust, caused by Phakopsora pachyrhizi, and increased yield.

Researchers point to ascr#18 as a potential strategy for crop protection with less dependence on pesticides. The compound acts on the plant's defensive capacity, with no direct effect identified on bacterial multiplication or fungal spore germination in the tests performed (doi 10.1038/s42003-026-10211-1).