|Brown, J - UNIV. OF ARIZONA|
|Czosnek, H - UNIV. OF JERUSALEM|
Submitted to: European Whitefly Symposium Proceedings
Publication Type: Abstract Only
Publication Acceptance Date: June 25, 2004
Publication Date: September 12, 2004
Citation: Shatters, R.G., Boykin, L.M., Mckenzie, C.L., Brown, J.K., Czosnek, H. 2004. Functional genomics discovery of bemisia tabaci (b biotype) cdnas encoding knottin-like proteins: do they play a defensive role?. European Whitefly Symposium Proceedings. Technical Abstract: 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 identified by comparative analysis of two expressed sequence tag 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. Greater than 3,000 clones were randomly selected and sequenced from each library. 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 in virus-free and geminivirus infected whitefly will be presented and data will be discussed with respect to the possible role these knottin-like proteins may have in defense.