1Indian Agricultrual Research Institute, Regional Station, Pune.
2Indian Agricultural Research Institute, New Delhi-110012.
Abstracts of Research Papers Presented during the National Symposium of Indian Virological Society at Unit of Plant Virology, Division of Plant Pathology, Indian Agricultural Research Institute, New Delhi-110 012, October 14–1.
Citrus tristeza clostero virus, an aphid transmitted viral pathogen occurs in most of the citrus growing areas of the world. In a recent survey of citrus orchards in and around Pune region of Maharashtra, a number of samples showing variability in symptom expression were collected from Kagzi lime, Mosambi and Sweet orange trees. These were grafted on K. lime and maintained in a greenhosue and symptom expression was recorded regularly. Six to eight months later samples taken from these plants using leaf midribs were tested by ELISA using both Polyclonal (CREC-1052) and Monoclonal (MCA-13) antibodies to CTV available at ACPV, IARI, New Delhi. Results showed that out of 16 samples 8 reacted positively to CREC-1052, indicating the presence of CTV. The positive samples were then tested with MCA-13, 5 of them showed positive reaction indicating presence of severe strain of CTV and remaining 3 samples which did not show positive reaction, revealing possibility of presence of mild strain of CTV among them. Therefore, these samples were subjected to RT-PCR, BD-PCR and sequencing procedures for further analysis of strains. The results revealed the presence of amplicons of three sizes ∼ 700 bp, 400 bp and 300 bp in both glasshouse samples as well as symptom less field sample, which is suggestive of a mixed infection due to severe and mild strains of CTV. When ∼ 700 bp PCR product obtained from a glasshouse maintained isolate was sequenced and analyzed, it revealed the presence of severe strain of CTV, similar in homology to earlier reports of severe strain. The present study highlights the need for molecular approaches for mild strain detection of CTV.
