Whitefly-transmitted geminiviruses belong to the Geminiviridae family, which includes a group of plant DNA viruses that occurs in tropical and subtropical regions worldwide and caused severe leaf curl diseases on many crops. In July 2011, symptoms of mild yellowing and curling of leaves were observed on Zinnia elegans in Hue City, Vietnam. To identify possible begomoviruses, two samples with typical symptoms (Z1 and Z2) were collected and total DNA was extracted using PlantGen DNA Kit (CoWin Biotech Co., China). Using begomovirus-specific degenerate primer pair AV494 and AC1048 to amply geminivirus capsid protein gene (3), a 586-bp DNA fragment was amplified from both collected samples. The PCR products from Z1 and Z2 were cloned and sequenced. The partial sequences from two isolates had 96.8% similarity to each other and most closely related to Ageratum yellow vein China virus (AYVCNV) (98% identity to GenBank Accession Nos. AM940137.1 and AJ849916.1). Using two degenerate primer pairs bego1 (5′-ACMGGCCYATGWAYMGGAAG-3′)/bego6 (5′-ACNGGDAARACRATGTGGGC-3′) and bego2 (5′-CTTDATRTTBTCRTCCATCC-3′)/bego3 (5′-CCWGGATTGCANARSAMGAT-3′) to amplify full-length viral genome from Z1 (1). The complete DNA-A sequence from Z1 were determined to be 2,741 nucleotides (JX911332), showed high levels of sequence identity (89% [JN809812] to 98% [AJ849916.1 and AJ558120]) with AYVCNV and shared 98% nucleotide sequence identity with AYVCNV-G68 (AJ849916.1) and AYVCNV-G13 (AJ558120). No DNA-B component nor DNA-β could be detected using primers described previously (4). Zinnia leaf curl virus, Ageratum enation virus, Tobacco leaf curl virus, and Alternanthera yellow vein virus have been reported to be associated with Zinnia leaf curl disease (2). To our knowledge, this is the first report of AYVCNV infecting Z. elegans. AYVCNV was first reported in A. conyzoides on Hainan Island, China, and could infect L. esculentum (Solanaceae), A. conyzoides (Asteraceae), or tobacco (Solanaceae). Our results further corroborate that AYVCNV can infect Asteraceae plants. Therefore, this virus may pose a serious threat to many plants.
References: (1) L. Lin et al. Plant Prot. 37:44, 2011. (2) P. Naveen et al. J. Biotechnol. Bioinform. 2:6, 2012. (3) S. D. Wyatt et al. Phytopathology 86:1288, 1996. (4) X. P. Zhou et al. J. Gen. Virol. 84:237, 2003.