Gene Expression in spp. Root and Crown during Infection.

causes major diseases in cucurbit crops worldwide. In this study, we inoculated this pathogen into subsp. susceptible MUCU-16 and tolerant M63. The gene expression of plant pathogenesis-related proteins chitinase (), lignin-forming peroxidase (), and defensin () and hormone-related enzymes salicylic acid () and ethylene () was analyzed for two weeks post-inoculation in root and crown tissues. Differentially expressed genes were found between genotypes, tissues, days post-inoculation, and inoculated/non-inoculated samples. After inoculation, and (crown) were downregulated in MUCU-16, while and were upregulated in M63. In inoculated samples, higher expression changes were presented on days 10-14 than on day 3 for , , and genes. Overexpression was higher for compared to the other tested genes, indicating good suitability as a marker of biotic stress. The overexpression of was higher in crown than in roots for both inoculated genotypes. The basal expression of and was higher in MUCU-16, but after inoculation, and gene expression were higher in M63. These changes suggest an association between upregulation and tolerance, and between downregulation and susceptibility.