Momol M T, Simone G W, Dankers W, Sprenkel R K, Olson S M, Momol E A, Polston J E, Hiebert E
University of Florida, North Florida Research and Education Center, Quincy 32351.
University of Florida, Department of Plant Pathology, Gainesville 32611.
Plant Dis. 1999 May;83(5):487. doi: 10.1094/PDIS.1999.83.5.487C.
In October 1998, symptoms characteristic of tomato yellow leaf curl virus (TYLCV) were observed on fresh market tomato (Lycopersicon esculentum Mill.) in four production fields, two in Decatur County, Georgia, and two in Gadsden County, Florida. Symptoms observed were plant stunting, reduced leaf size, yellow leaf margins, and mottling. The incidence of symptomatic plants was less than 1% in all fields examined. In most cases, symptoms were observed only on the upper portion of plants, suggesting these plants had been infected by secondary spread from an unknown source. Nuclear inclusions characteristic of geminiviruses were observed by light microscopy in leaf tissue from symptomatic plants (1). To identify the geminivirus, total DNA from infected plants was extracted from six symptomatic tomato plants (two from Georgia and four from Florida) for polymerase chain reaction (PCR; J. E. Polston, personal communication). DNA was amplified with geminivirus DNA A degenerate primer set PAL1v1978 and PAR1c496 (2) from these extracts in addition to extracts from a known TYLCV-infected, a tomato mottle virus (ToMoV)-infected, and a healthy tomato plant. A PCR product of 1.4 kb was obtained from plants with TYLCV-like symptoms, while a 1.4-kb product and a 1.1-kb product were obtained from extracts of the known TYLCV-infected and ToMoV-infected tomato plants, respectively. No PCR product was obtained from extracts of healthy tomato plants. The 1.4-kb PCR products from one Georgia sample and one Florida sample were compared with those of TYLCV and ToMoV by restriction enzyme (RE) digestion with EcoRI and ClaI. The RE pattern of the 1.4-kb fragment from both samples was identical to the RE pattern of TYLCV and different from that of ToMoV. Adult and immature whiteflies collected from the fields where TYLCV was found were identified as Bemisia tabaci, the vector of TYLCV, but the biotype was not established. This report of TYLCV in south Georgia and north Florida extends the geographic range of TYLCV in the U.S. northward approximately 100 km. Georgia is the second state in which TYLCV was found since its initial detection in south Florida in July 1997 (J. E. Polston, personal communication). Monitoring of silverleaf whitefly populations and detection of TYLCV on alternate hosts will continue in order to estimate the potential impact of this virus on south Georgia and north Florida agriculture. References: (1) R. G. Christie and J. R. Edwardson. Plant Dis. 70:273, 1986, (2) M. R. Rojas et al. Plant Dis. 77:340, 1993.
1998年10月，在四个生产田的鲜食番茄（Lycopersicon esculentum Mill.）上观察到番茄黄化曲叶病毒（TYLCV）的特征症状，其中两个田位于佐治亚州迪凯特县，另外两个位于佛罗里达州加兹登县。观察到的症状包括植株矮化、叶片变小、叶缘发黄和斑驳。在所有检查的田块中，有症状植株的发生率均低于1%。在大多数情况下，症状仅在植株上部观察到，这表明这些植株是通过未知来源的二次传播而被感染的。通过光学显微镜在有症状植株的叶片组织中观察到双生病毒特有的核内含体（1）。为了鉴定双生病毒，从六株有症状的番茄植株（两株来自佐治亚州，四株来自佛罗里达州）中提取总DNA，用于聚合酶链反应（PCR；J. E. Polston，个人交流）。除了从已知感染TYLCV、感染番茄斑驳病毒（ToMoV）和健康番茄植株的提取物外，还用双生病毒DNA A简并引物对PAL1v1978和PAR1c496（2）从这些提取物中扩增DNA。从具有TYLCV样症状的植株中获得了1.4 kb的PCR产物，而从已知感染TYLCV和感染ToMoV的番茄植株提取物中分别获得了1.4 kb的产物和1.1 kb的产物。从健康番茄植株提取物中未获得PCR产物。通过用EcoRI和ClaI进行限制性内切酶（RE）消化，将来自佐治亚州一个样品和佛罗里达州一个样品的1.4 kb PCR产物与TYLCV和ToMoV的产物进行比较。两个样品中1.4 kb片段的RE图谱与TYLCV的RE图谱相同，与ToMoV的不同。从发现TYLCV的田块中采集的成虫和若虫烟粉虱被鉴定为烟粉虱，即TYLCV的传播媒介，但未确定生物型。这份关于佐治亚州南部和佛罗里达州北部TYLCV的报告将TYLCV在美国的地理范围向北扩展了约100公里。佐治亚州是自1997年7月在佛罗里达州南部首次检测到TYLCV以来第二个发现该病毒的州（J. E. Polston，个人交流）。将继续监测银叶粉虱种群并在替代寄主上检测TYLCV，以评估这种病毒对佐治亚州南部和佛罗里达州北部农业的潜在影响。参考文献：（1）R. G. Christie和J. R. Edwardson。植物病害。70:273，1986年，（2）M. R. Rojas等人。植物病害。77:340，1993年。
