Influence of Temperature on Salicylate-Induced Components in Tomato Plants Immune System under Invasion with Root-Knot Nematode Meloidogyne incognita

The tomato gene Mi-1,2 is currently the only commercially available source of resistance to the root-knot nematode Meloidogyne incognita, which loses activity when soil temperatures exceed 28°C. The study aimed to investigate the components of the tomato immune system to root-knot nematode associated with salicylic acid (SA) at elevated (34°C) and normal (25°C) temperatures. The obtained results showed that the Mi-1,2-mediated immune response is disrupted at 34°C. At elevated temperatures in plants infested with nematodes, the synthesis of salicylic acid and the activity of phenylalanine ammonia lyase are reduced, and catalase is inhibited, a decrease in the activity of which was discovered at the stage of nematode penetration into the roots and the creation of feeding structures-giant cells. Elevated temperature decreased the activity of the PR-1 gene, a marker of systemic plant resistance. These results provide important information on the sensitivity temperature of the Mi-1.2 resistance gene and the effect of elevated temperature on SA-dependent components of the immune system that are associated with tomato resistance to the nematode.