Effects of salicylic acid, jasmonic acid and reactive oxygen species on the resistance of Solanum peruvianum to Meloidogyne incognita

Genes that are resistant to Meloidogyne incognita in tomato are mainly members of the Mi gene family. The Mi-3 gene is a heat-stable R gene that retains resistance under high-temperature soil conditions (below 32 degrees C). The findings of a preliminary investigation of the signaling pathway of Mi-3-mediated resistance combined with that of a previous transcriptome analysis showed that Mi-3-mediated resistance mainly occurred in the early stages of nematode infection. An coexpression analysis of key differentially expressed genes (DEGs) related to disease resistance at 3 dpi filtered 7 DEGs as the hub genes that encoded key proteins, including CPKs, RBOHs, HSP, EDS1, and SAPK7. An analysis of the key resistant signal plant hormone pathways, namely, salicylic acid (SA) and jasmonic acid (JA) showed that both external sprays could alleviate the pathogenicity caused by inactivation of Mi-3 at high temperature (34 degrees C). Additionally, in the early stage of nematodes inoculation, the initial synthesis of SA and JA in the plant under a state of disease resistance (25 degrees C) was high. The levels of DEGs (LOXs and PALs) involved in the biosynthesis of both plant hormones were up-regulated in the 25 degrees C assay. Additionally, after inoculation with nematodes, the high expression of the active oxygen synthesis genes (RBOHs) at 25 degrees C and the activity determination of antioxidant enzymes (superoxide dismutase (SOD), POD, and catalase (CAT)) indicated that the instantaneous accumulation of reactive oxygen species (ROS) was likely to play a positive role in Mi-3-mediated disease resistance.