Association of Tomato yellow leaf curl virus and Chili leaf curl virus with leaf curl disease of radish and the synergistic interaction on Nicotiana benthamiana

Leaf yellowing and rolling with slight crinkling was observed in radish plants in Oman, indicative of a begomovirus infection. Viral sequences from radish were 99% identical to sequences of Tomato yellow leaf curl virus (TYLCV) and Chilli leaf curl virus (ChiLCV), from Oman. No beta- or alpha-satellites were detected. Infectious clones were developed and infectivity analyses of isolated viruses were done in a model host Nicotiana benthamiana. Both viruses, when inoculated separately, produced typical symptoms; however, symptom severity increased when these viruses were co-inoculated. Southern analyses confirmed that virus accumulation was high when both viruses were inoculated as compared to independent inoculation. Real-time qPCR analyses showed that copy number of both viruses was 1 X 10⁶ copies when N. benthamiana plants were inoculated with either TYLCV or ChiLCV; however, the copy number increased to 1 X 10⁸ copies when the two viruses were co-inoculated together in N. benthamiana.