The reaction of four pumpkin varieties to cucumber mosaic virus by analyzing the expression of PAL and PR2 genes

Cucumber mosaic virus (CMV) is one of the most important pathogenic cucurbit viruses. Identifying and growing resistant or tolerant varieties is the best method for disease control. The present study was conducted to investigate the response of four pumpkin varieties to CMV by assessing the expression of genes involved in resistance (PAL, PR2).

Forty samples of pumpkin leaves with suspected disease were collected from the farms in northwestern Iran and analyzed using the TAS-ELISA test. To study the response of the four pumpkin varieties Asma, Pars, Prof and PS grown in this region, a CMV isolate was inoculated into the plants in a greenhouse experiment after its biological purification. TAS-ELISA and semi-quantitative (Sq) RT-PCR tests were used to examine the virus concentration in pumpkin varieties. The disease severity index was evaluated 30 days after inoculation. The expression level of PAL and PR2 genes was also checked by quantitative real-time PCR technique.

Of the 40 samples, 16 samples were infected with CMV. The study of virus titer revealed that the virus concentration and disease severity index were higher in Pars and Proof varieties than in PS and Asma varieties. The expression of PAL and PR2 genes was increased in all varieties compared to control but was higher in PS cultivar followed by Asma.

PS and Asma varieties have higher CMV tolerance and their wider cultivation is recommended for disease control.