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Title: Molecular Characterization of the Meyer Lemon Isolate of Citrus Tatter Leaf Virus: Complete Genome Sequence and Development of Biologically Active In Vitro Transcripts

item Tatineni, Satyanarayana - Ts
item Afunian, Mohammad
item Hilf, Mark
item Gowda, Siddarame
item Dawson, William
item Garnsey, Stephen

Submitted to: Phytopathology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/17/2008
Publication Date: 3/10/2009
Publication URL:
Citation: Tatineni, S., Afunian, M.R., Hilf, M.E., Gowda, S., Dawson, W.O., Garnsey, S.M. 2009. Molecular Characterization of Citrus tatter leaf virus Historically Associated with Meyer Lemon Trees: Complete Genome Sequence and Development of Biologically Active In Vitro Transcripts. Phytopathology Volume 99, Pages 423-431.

Interpretive Summary: Citrus tatter leaf virus (CTLV) was initially reported from California as a latent infection in Meyer lemon trees, which was likely originated when infected Meyer lemon was introduced into the United States from China in 1906. The Meyer lemon isolate of CTLV, CTLV-ML, induces bunion incompatibility of citrus trees grafted on the widely used trifoliate hybrid rootstocks. The causal agent of this virus has not been characterized molecularly, hindering both the understanding of how CTLV causes disease and the development of management strategies for the citrus industry. In this study, we determined the genome sequence of CTLV-ML to be 6496 nucleotides and the genome organization is similar to other reported capilloviruses. Based on genome sequence, the CTLV-ML was identified as a strain of Apple stem grooving virus, the type member of Capillovirus genus. The genome sequence allowed us to develop infectious cDNA clones for CTLV-ML, which would allow further studies on virus genome expression and molecular understanding of CTLV-induced incompatibility of citrus trees grafted on trifoliate oranges.

Technical Abstract: Citrus tatter leaf virus isolated from Meyer lemon trees (CTLV-ML) from California and Florida induces bud union incompatibility of citrus trees grafted on the widely used trifoliate and trifoliate hybrid rootstocks. The complete genome sequence of CTLV-ML was determined to be 6,495 nucleotides (nts), with two overlapping open reading frames (ORFs) and a poly (A) tail at the 3' end. The genome organization is similar to other capilloviruses, with ORF1 (nts 37 to 6,354) encoding a putative 242-kDa polyprotein which contains replication-associated domains plus a coat protein (CP), and ORF2 (nts 4,788 to 5,750), which is located within ORF1 in a different reading frame and encodes a putative movement protein. Although the proteins encoded by CTLV-ML possesses 84 to 96% amino acid sequence identity with strains of Apple stem grooving virus (ASGV), we observed two strikingly different regions in ORF1: variable region I (amino acids 532 to 570) and variable region II (amino acids 1,583 to 1,868), with only 15 to 18 and 56 to 62% identities, respectively, with the corresponding regions of ASGV strains. Conditions for a herbaceous systemic assay host were optimized in which the wildtype virus induced systemic infection in Phaseolus vulgaris cv. Light Red Kidney (LRK) bean plants at 19 or 22°C but not at higher temperatures. In vitro transcripts generated from full-length cDNA clones induced systemic symptoms on LRK bean plants similar to that of the wild-type virus. Replication of the recombinant virus was confirmed by hybridization of a 5' positive-stranded RNA-specific probe to a genome-sized RNA and by reverse-transcription polymerase chain reaction.