Production of Metabolites During the Interaction of Susceptible and Resistant Melon Genotypes (Cucumis Melo L) With the Fungus Monosporascus Cannonballus

Abstract

Abstract Background Vine decline disease (VDD) caused by the fungus Monosporascus cannonballus (MC), is a major threat to melons (Cucumis melo L.) production worldwide. Nonetheless, little is known about the metabolites produced during the interaction of melon plants with this pathogen. Thus, the goal of this study was to identify and measure quantities as well as time of appearance of metabolites produced during the interaction of a susceptible and a resistant genotype with the pathogen MC. A susceptible genotype labeled TAM-Uvalde and a resistant genotype labeled USDA PI 124104 were grown and inoculated with MC. Amino and phenolic acids as well as hormones were measured before inoculation (0 hours) and 24, 48, 72 hours, and 6 weeks after inoculation, using high performance liquid chromatography analysis. Results Several metabolites were identified and their quantities as well as time of appearance were measured in both genotypes. Interestingly, the presence of hydroxy proline seems to be associated with susceptibility since it was always up-regulated in higher quantities in response to pathogen infection in the genotype TAM-Uvalde. Also, the up-regulation in higher quantities of ɤ-amino butyric acid in the genotype TAM-Uvalde 24 and 48 hours after inoculation suggests more penetration of the pathogen in its roots. Additionally, phthalic acid was also found in all the treatments, which may be associated with allelopathic responses of melon plants. Finally, citrulline and gibberellic acid were also found in the inoculated treatments. However, their origin and roles, in this case, need to be clarified. Conclusions Taken together, hydroxy proline and ɤ-amino butyric acid could be used as markers of susceptibility to VDD caused by MC, which could be useful in developing resistant varieties.