Plant defense elicitor, 2, 4-dichloro-6-{(E)-[(3-methoxyphenyl) imino] methyl} phenol (DPMP) and its mode of action against fungal pathogen Alternaria solani in tomato (Solanum lycopersicum L.)

Abstract

Biotic stress factors are one of the major constraints plants face, and they significantly affect production and yield. There are multiple ways to cope with stress factors, including genetic enhancement. When they cannot provide sufficient protection, pesticides are commonly applied. Plant defense elicitors are a new approach for boosting plants' natural immune responses and tolerance levels. The newly identified promising plant defense elicitor; 2, 4-dichloro-6-{(E)-[(3-methoxyphenyl) imino] methyl} phenol (DPMP) was previously studied against the oomycete Hyaloperonospora arabidopsidis, the bacterial pathogens Pseudomonas syringae and Clavibacter michiganensis ssp michiganensis and found to induce disease resistance against these phytopathogens. However, it was not tested against fungal pathogens. Here for the first time, DPMP was evaluated against one of the most destructive fungal pathogens, Alternaria solani. Disease severity and plant development were evaluated. The results revealed that DPMP neither inhibited nor enhanced the disease severity of A. solani. Gene expression of several salicylic acid, jasmonic acid, and ethylene pathway-related genes (Pti4, TPK1b, Pto kinase, PRB1 2, SABP2, and PR3) were also analyzed. According to the results, while DPMP induces PRB1-2, TPK1b, and Pto kinase gene expressions, the protection against A. solani does not occur via these genes. PR3 is one of the most important genes for defense responses against necrotrophic pathogens, and DPMP downregulated gene expression of PR3. These results demonstrated that DPMP mostly takes a role through the SA-related defense pathway and was effective against biotrophic and hemibiotrophic pathogens. However, it is not suitable for protection against the necrotrophic pathogen A. solani. Further research may pinpoint the activity of DPMP on the defense pathway and provide a better understanding of the mode of action for DPMP and other plant elicitors for specific plant protection solutions.