|Roy, Gourgopal - UNIV OF CALIF-DAVIS|
|Ullman, Diane - UNIV OF CALIF-DAVIS|
Submitted to: Phytopathology
Publication Type: Abstract Only
Publication Acceptance Date: March 30, 2005
Publication Date: August 1, 2005
Citation: Roy, G., Yokomi, R.K., Ullman, D. 2005. Amino acid sequence variations assoicated with aphid transmissibility of citrus tristeza virus.[Abstract]. Phytopathology. 95:S91. Technical Abstract: Citrus tristeza virus isolates were collected from the San Joaquin Valley of California. Different transmission phenotypes were identified among these isolates with Aphis gossypii and Toxoptera citricida, the brown citrus aphid (BrCA). To investigate the differential transmissibility at the genomic level, we designed overlapping primers and used RT-PCR to sequence the 3' end of the genome [nine open reading frames (ORFs)] of six isolates with different transmission phenotypes. A specific amino acid substitution at position 412 from positively charged arginine (R) to neutral glutamine (Q) was observed in the heat shock protein 70 homolog (Hsp70h) region of two poorly aphid transmissible (0-2%) isolates. This substitution is interesting because it is predicted to change the charge density on the surface of the Hsp70h protein. This protein is required for virion assembly in CTV and is known to be associated with virion proteins in Beet yellows virus, the type member of the family Closteroviridae. These data suggest that Hsp70h may play a role in facilitating aphid transmission of CTV. We are testing this hypothesis using recombinant proteins and in vitro transmission assays.