A New Begomovirus Inducing Yellow Mottle in Okra Crops in Mexico is Related to Sida yellow vein virus

Abstract

Okra (Abelmoschus esculentus L. Moench), an annual vegetable of African origin, has been cultivated in Mexico for 3 decades. Since 2000, the most important okra-producing areas in the states of Guerrero and Morelos have been affected by a disease causing yellow streak and severe distortion of fruits, a bright yellow mottle, and curling and distortion of leaves. These symptoms and the presence of whiteflies (Bemisia tabaci Gennadius) suggest a viral etiology. Samples of symptomatic plants from three localities, Iguala (Guerrero), Mazatepec, and Xochitepec (Morelos) were collected in November 2004 and tested for the presence of viruses. Single whitefly transmissions, grafting experiments, and experimental inoculation of healthy plants by biolistic delivery of DNA extracts from symptomatic plants consistently induced yellow mottle in okra plants and suggest the presence of a DNA virus. Total DNA extracts from symptomatic plants from field and greenhouse conditions were analyzed by Southern blot hybridization using the coat protein gene of Pepper yellow vein huasteco virus as a probe at low stringency. More than 20 positive samples were subsequently used as templates for polymerase chain reaction (PCR) amplification with the degenerate primers pRepMot and pCPMot (1). PCR products of approximately 600 bp were obtained and directly sequenced. Eight isolates from the three localities (GenBank Accession Nos. AY624016 to AY624023) shared 97 to 100% nucleotide identity but were significantly different from other known begomoviruses. The complete genome A sequence of one isolate from Mazatepec (Ok-M3) was determined using PCR amplification of viral DNA with the degenerate primers PAL1v1978 and PAL1c1960 (3) and four new universal primers, pRepQGR (5′-TCCCTGWATGTTYGGATGGAAATG-3′), pRepQGR-rev (5′-CATTTCCATCCRAACATWCAGGGA-3′), pCp70-MAC (5′-GTC TAGACCTTRCANGGNCCTTCACA-3′), and pCp70-MAC-rev (5′-GAA GGSCCNTGYAAGGTNCAGTC-3′). Partially overlapping PCR products of 0.9, 1.3, and 1.7 kb were cloned into pGEM-T easy vector (Promega, Madison, WI) and sequenced. The 2612-bp DNA-A sequence of Ok-M3 (GenBank Accession No. DQ022611) was compared with sequences available from GenBank using the Clustal alignment method (MegAlign, DNASTAR software, London). The highest sequence identity was obtained with Sida yellow vein virus (SiYVV; Accession No. Y11099), Sida golden mosaic Honduras virus (SiGMHV; Accession No. Y11097), and Chino del tomate virus (CdTV; Accession No. AF101478) that had 85.4, 85.4, and 84.4% nucleotide sequence identity with the Ok-M3 isolate, respectively. Comparative analysis of the intergenic region of the Ok-M3 isolate and its closest relatives revealed that these viruses display different putative Rep-binding sites (iterons): Ok-M3 (GGTACACA), SiYVV (GGAGTA), and SiGMHV (GGKGTA). Current taxonomic criteria for the classification of begomoviruses establishes that less than 89% DNA-A nucleotide sequence identity with the closest relative of a virus is indicative of a separate species (2). Our results indicate that the okra-infecting virus identified in this study is a new begomovirus species, and the provisional name of Okra yellow mottle Mexico virus is proposed. References: (1) J. T. Ascencio-Ibañez et al. Plant Dis. 86:692, 2002. (2) C. Fauquet et al. Arch. Virol. 148:405, 2003. (3) M. Rojas et al. Plant Dis. 77:340, 1993.

Diversity and phylogeography of begomovirus-associated beta satellites of okra in India

“…The malvaceous plants in the New World are affected by bipartite begomoviruses [ 27 - 29 ] betasatellites not apparently occurring in the New World [ 7 ]. In the Old World begomoviruses infecting okra are invariably associated with betasatellites and are, for the few which have been characterized, monopartite--lacking the DNA B component.…”

Roles and interactions of begomoviruses and satellite DNAs associated with okra leaf curl disease in Mali, West Africa

“…A new begomovirus species, okra yellow crinkle virus (OYCrV) (Shih et al, 2006), was recently shown to be associated with OLCD in Mali. In other parts of the world, similar diseases of okra are also associated with begomovirus infection (De La Torre-Almaraz et al, 2006;Idris & Brown, 2002;Jose & Usha, 2003;Zhou et al, 1998).…”

Una nueva cepa del Virus del Chino del Tomate aislado de plantas de soya (Glycine max L.) en México

“…. Viral DNA amplifications were carried out using the universal primers for begomoviruses: pRep-DGR (Méndez et al, 2006), PrCP70-Mot, prRepQGR-rev (De la Torre et al, 2006) and prC889 (Brown et al, 2001). The PCR products comprise the complete A component.…”