First Report of Tomato yellow leaf curl virus Associated with Tomato Yellow Leaf Curl Disease in California

Abstract

Tomato yellow leaf curl disease caused by the whitefly-transmitted begomovirus (genus Begomovirus, family Geminiviridae) Tomato yellow leaf curl virus (TYLCV) is one of the most damaging diseases of tomato. TYLCV was introduced into the New World in the early 1990s and by the late 1990s, it was found in Florida (2). In 2005 and 2006, the virus was reported from northern Mexico (states of Sinaloa and Tamaulipas) (1) and subsequently from Texas and Arizona. In March 2007, tomato (Lycopersicon esculentum) plants growing in a greenhouse in Brawley, CA showed TYLCV-like symptoms including stunted upright growth, shortened internodes, and small upcurled leaves with crumpling and strong interveinal and marginal chlorosis. These plants also sustained high populations of whiteflies. Symptomatic tomato leaves and associated whiteflies were collected from inside the greenhouse. Leaf samples also were collected from symptomless weeds (cheeseweed [Malva parviflora] and dandelion [Taraxacum officinale]) outside of the greenhouse. Total nucleic acids were extracted from 41 symptomatic tomato leaf samples, seven samples of adult whiteflies (approximately 50 per sample), and six leaf samples each from cheeseweed and dandelion. PCR analyses were performed with the degenerate begomovirus primers PAL1v1978 and PAR1c496 (3) and a TYLCV capsid protein (CP) primer pair (4). The expected size of approximately 1.4-kbp and 300-bp DNA fragments, respectively, were amplified from extracts of all 41 symptomatic tomato leaves and adult whitefly samples; whereas the 300-bp DNA fragment was amplified from all six cheeseweed samples and four of the six dandelion samples. Sequence analysis of a portion of the AC1/C1 gene from the approximately 1.4-kbp fragment amplified from 12 tomato leaf samples and four whiteflies samples revealed 99 to 100% identity with the homologous sequence of TYLCV from Israel (GenBank Accession No. X15656). The putative genome of the California TYLCV isolate was amplified using PCR and an overlapping primer pair (TYBamHIv: 5′-GGATCCACTTCTAAATGAATTTCCTG-3′ and TYBamHI2c: 5′-GGATCCCACATAGTGCAAGACAAAC-3′), cloned and sequenced. The viral genome was 2,781 nt (GenBank Accession No. EF539831), and sequence analysis confirmed it was a bona fide isolate of TYLCV. The California TYLCV sequence is virtually identical (99.7% total nucleotide and 100% CP amino acid sequence identity) to a TYLCV isolate from Sinaloa, Mexico (GenBank Accession No. EF523478) and closely related to isolates from China (AM282874), Cuba (AJ223505), Dominican Republic (AF024715), Egypt (AY594174), Florida (AY530931), Japan (AB192966), and Mexico (DQ631892) (sequence identities of 98.2 to 99.7%). Together, these results establish that TYLCV was introduced to California, probably from Mexico. Because the tomatoes in this greenhouse were grown from seed, and symptoms did not appear until after initial fruit set, the virus was probably introduced via viruliferous whiteflies. To our knowledge, this is the first report of TYLCV infecting tomato plants in California. References: (1) J. K. Brown and A. M. Idris. Plant Dis. 90:1360, 2006. (2) J. E. Polston et al. Plant Dis. 83:984, 1999. (3) M. R. Rojas et al. Plant Dis. 77:340, 1993. (4) R. Salati et al. Phytopathology 92:487, 2002.

Multiple Introductions of the Old World Begomovirus Tomato yellow leaf curl virus into the New World

“…Our analyses further confirm that TYLCV-US:CA is most closely related to the western Mexican viruses (38) and therefore likely spread over the border from Mexico (Fig. 1).…”

“…After the confirmation of TYLCV in Sinaloa, TYLCV was found farther north in Mexico (14), in Texas (16), in Arizona (14), and in southern California (38). Our analyses further confirm that TYLCV-US:CA is most closely related to the western Mexican viruses (38) and therefore likely spread over the border from Mexico (Fig.…”

“…By contrast, most of the sequences isolated from the United States have been found near the Caribbean (e.g., Florida [34], Louisiana [45], Georgia [22], and Mississippi [15]), even though the virus has recently been identified in western states, such as California and Arizona (14,38). In all three trees, the sequences from eastern Mexico, the eastern United States, and the Caribbean grouped together, forming an eastern North America and Caribbean (ENAC) clade, albeit with strong support in the CP gene only (bootstrap values of 51% [ Fig.…”

Ongoing geographical spread of Tomato yellow leaf curl virus

“…Geographical clustering was done as described by Lefeuvre et al (2010), using the centroid hierarchical clustering method (Rokach and Maimon, 2005) implemented in R (R Core Team, 2013) to determine the most appropriate regional grouping scheme for the phylogeographic analyses.…”

Gene-Based Markers for the Tomato Yellow Leaf Curl Virus Resistance GeneTy-3

“…Tomato yellow leaf curl virus (TYLCV) disease transmitted by the whitefly (Bemisia tabaci) is one of the most devastating diseases causing quality and yield reduction in tomato (Liu et al 2013). According to recent reports, TYLCV disease is spreading due to global warming, with current outbreaks in the United States and China (Rojas et al 2007;Zhang et al 2009;Melzer et al 2010). Recently, TYLCV incidence was also reported in Korea (Lee et al 2010).…”