Submitted to: International Organization of Citrus Virologists Proceedings
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/13/2005
Publication Date: 8/13/2005
Citation: Hilf, M.E. 2005. Selective resistance to citrus tristeza virus in red shaddock (citrus grandis). International Organization of Citrus Virologists Proceedings. Interpretive Summary:
Technical Abstract: General resistance to systemic infection by CTV occurs in trifoliate orange (Poncirus trifoliata) and in some hybrids of P. trifoliata and Citrus spp. In pummelo (C. grandis) and in hybrids of grapefruit (C. paradisii) and P. trifoliata, resistance is expressed against only some isolates of CTV, while others can systemically infect these hosts. Seedlings of Red Shaddock (C. grandis) were inoculated with single or mixed infections of isolates of CTV genetically characterized as similar to the T30, T36, and VT isolates. A general anti-CTV polyclonal antibody and the isolate specific monoclonal antibody MC13 were used for serological assessment of systemic infection by CTV, and immunocapture-RT-PCR with sequence specific primers was used to genetically characterize the CTV systemically infecting the seedlings. Serological and molecular analysis showed that CTV of the T30 genotype replicated in 3 of 17 inoculated seedlings, and CTV of the VT genotype replicated in 8 of 15 inoculated seedlings. In contrast, CTV of the T36 genotype replicated in 21 of 21 inoculated seedlings. The replication of the T36 genotype in all inoculated seedlings indicates a potential lack of resistance to the T36 genotype, whereas the apparent lack of systemic infection of the T30 and VT genotypes in all inoculated seedlings indicates possible resistance in some Red Shaddock seedlings, but that variability exists in the expression of resistance among Red Shaddock seedlings.