Reaction of commercial canola varieties and lines against Turnip mosaic virus (TuMV) isolate

Turnip mosaic virus (TuMV) is one of the most prevalent viruses of canola fields in Iran. Use of resistant varieties is the best recommended manner to control losses caused by TuMV. In this research, the reaction of 11 commercial varieties and two lines of canola (Brassica napus L.) was investigated against a Netherland TuMV isolate under greenhouse condition. The seedlings were inoculated using TuMV-infected tobacco (Nicotiana benthamiana) sap at 3-5 leaf stage and their reaction was evaluated based on symptom severity index and ELISA OD405 values at four and the mean values of fresh and dry weights of plants at seven weeks after inoculation. This study was performed in a factorial experiment and randomized complete block design with three replications and each repeat involved four experimental units for each group of inoculated and uninoculated plants. Virus-infection was confirmed by RT-PCR. In accordance with evaluated parameters, reaction of varieties to the virus was significantly different. At probability level of 5%, Karaj3 was tolerant while Karaj2 was the most susceptible, RGS003 and Karaj1 were susceptible and the rest of canola varieties/lines were moderately susceptible to TuMV. Difference of OD405 values in ELISA was meaningless among inoculated plants of canola varieties/lines. Among canola varieties/lines, only fresh and dry weights of Karaj2 line was reduced significantly in virus-infected plants. The scoring system (0 to 8) for the symptoms severity of TuMV in canola was introduced for the first time in this research.