Study on the antiviral activity of Weeping willow, Yarrow and common Nettle plant ethanolic extracts on Cucumber mosaic virus infection in cucumber under greenhouse conditions

In this research the antiviral activity of medicinal plants including Weeping willow, Yarrow and Common Nettle ethanolic extracts against CMV-Fny infection in cucumber plant was explored under the greenhouse conditions. To this end, cucumber seedlings were mechanically inoculated with the CMV-Fny. The extract of the mentioned plants was added directly into the plants' rhizosphere at 200 ppm, 800 ppm and 1000 ppm concentrations. CMV-infection level in inoculated as well as young grown leaves was tested by DAS-ELISA in 3, 6, 9 and 12 days post-inoculation. Peroxidase (POX) enzyme activity was assessed for the cucumber seedlings which showed maximum virus inhibition at 12 days post-inoculation and the expression level of inhibitor of viral replication (IVR) gene was also examined by semi-quantitative RT-PCR (sq-RT-PCR) method for them at this time. ELISA results indicated that at 12 days after virus inoculation, CMV-Fny protein titer in inoculated and young grown leaves as well as disease severity index (DSI) decreased in cucumber seedlings treated with the plant extracts compared to the negative control. The most decreased level of CMV-titer observed 12 days at mature inoculated and young leaves by applying 1000 ppm concentration of nettle and 200 ppm of yarrow extracts. The expression level of IVR gene and POX enzyme specific activity increased in treated cucumber seedlings at 12 days post inoculation, represent a systemic resistance activity against CMV-infection, after extracts treatment.