Abstract
Cucumber mosaic virus (CMV) was obtained from naturally infected tomato (Solanum lycopersicum L.) plants showing yellowing leaves, mottling, leaf curl, and leaf shoestring. Infected samples were tested by direct ELISA with antiserum to CMV, and infected samples that had positive reactions to CMV antiserum were separated. Viral identity was confirmed by host range and serological tests. RT-PCR fragment of the expected size 512 bp was amplified. On the other hand, we studied the inhibitory effects of two Trichoderma species (Trichoderma harzianum and T. viride) on inducing systemic resistance in infected seedlings. The infected tomato seedling (control) had an average significant disease severity that was higher than that of the other treatments, whereas tomato seedling treatment with PD1 and PD2 resulted in disease suppression of 98.20% and 96.80%, respectively, which was significantly higher than that of plants treated with PF1 (85.60%) or PF2 (71.40%) individually. The effects of T. harzianum and T. viride treatments on many of the protein patterns in healthy and infected tomato seedlings under inoculation by CMV were confirmed by a novel subunit of protein band numbers (10, 14, 19, 29, 43, 54, 55, 65, and 72) compared with PA. The absence of these protein bands in PA, PC, and PF1, PF2 and their presence in PB1, PB2 and PD1, PD2 could be attributed to the effects of treatment with Trichoderma. The results obtained suggest the potential for Trichoderma to protect tomato seedlings against CMV through stimulation of plants to produce pathogenesis-related (PR) proteins and activation of induced systemic resistance (ISR) against virus infection by accumulating secondary metabolites including terpenoids, phenolics, and alkaloids.