Submitted to: Plant and Animal Genome Conference Proceedings
Publication Type: Abstract Only
Publication Acceptance Date: 11/11/2004
Publication Date: 1/17/2005
Citation: Shatters, R.G., Mckenzie, C.L., Boykin, L.M., Czosnek, H., Brown, J. 2005. Whitefly (bemisia tabaci b biotype) functional genomics: expressed sequence tag (est) analysis of whtefly - begomovirus interactions. Plant and Animal Genome Conference Proceedings. Interpretive Summary:
Technical Abstract: Random EST sequencing of greater than 3,000 cDNA clones was performed from each of three adult whitefly Bemisia tabaci (biotype B) cDNA libraries: adult whitefly feeding on healthy tomato, and tomato infected with either of two economically important begomoviruses: Tomato yellow leaf curl virus (TYLCV) or Tomato mottle virus (ToMoV). The cDNAs encoding knottin-like proteins were more abundant in virus infected whitefly libraries. Knottins are a group of small proteins defined structurally as having a "disulfide through disulfide knot", and have been described in humans, plants, and arthropods. Functionally, knottins play a role as antimicrobial proteins, proteinase inhibitors, and toxins. Two knottin-like sequences were more abundant in libraries constructed from Bemisia tabaci (biotype B) adults sampled either from a colony feeding on healthy tomato, or a colony feeding on Tomato mottle virus (ToMoV; a whitefly transmitted geminivirus) infected tomato. Sequences from the two libraries were combined and clustered using the contig function of the Sequenchertm sequence analyzing program. Clusters containing sequences predominantly or solely from ToMoV carrying whitefly were identified. Two cluster consensus sequences encoding proteins with similarity to knottins were discovered and designated btk-1 and btk-2. Individual clones comprising these clusters were randomly selected 12 and 7 times in the ToMoV library for btk-1 and btk-2, respectively. However, btk-1 was sequenced only once in the cDNA library from whiteflies feeding on healthy tomato, and btk-2 was never sequence from this library. Protein sequence analysis showed that both btk-1 and -2 contain the six conserved cysteine residues present in knottin proteins. Quantitative detection of both transcripts support the EST analysis showing that the presence of the virus induced btk abundance. Results suggest the knottins my function as defensive proteins.