Aguilar E, Sengoda V G, Bextine B, McCue K F, Munyaneza J E
Zamorano University, Km 30 carretera a Danlí, Tegucigalpa, Honduras.
USDA-ARS, Yakima Agricultural Research Laboratory, 5230 Konnowac Pass Road, Wapato, WA 98951.
Plant Dis. 2013 Oct;97(10):1375. doi: 10.1094/PDIS-04-13-0354-PDN.
Tomato (Lycopersicum esculentum) crops grown in several departments of Honduras and heavily infested with the psyllid Bactericera cockerelli were observed in April of 2012 with plant symptoms suggestive of "Candidatus Liberibacter solanacearum" infection. B. cockerelli is a serious pest of potato, tomato, and other solanaceous plants and a vector of "Ca. L. solanacearum" (1,2,3,4). The symptoms included overall chlorosis, severe stunting, leaf cupping, excessive branching of axillary shoots, and leaf purpling and scorching (2,3). Disease incidence ranged from 5 to 50% symptomatic plants per field. Tomato (cv. Pony) plant samples were collected from two psyllid-infested commercial fields in the municipalities of Danli and Comayagua in the departments of El-Paraiso and Comayagua, respectively. Total DNA was extracted from leaf tissues of 50 and 20 symptomatic and asymptomatic plants, respectively, with the cetyltrimethylammonium bromide (CTAB) buffer extraction method (1,3). The DNA samples were tested for "Ca. L. solanacearum" by PCR with primer pairs specific for 16S rDNA (OA2 and OI2c) and the outer membrane protein gene (OMB 1482f and 2086r) of the bacterium (1,2). Ten (20%) of the 50 symptomatic tomato samples were positive for "Ca. L. solanacearum" using both primer pairs and the remaining samples were negative for the bacterium with both primer sets. None of the 20 asymptomatic plants tested positive for "Ca. L. solanacearum". Amplicons from DNA of two plant samples (one plant/municipality) with each primer pair were cloned and four clones of each of the four amplicons were sequenced. BLASTn analysis of the 16S rDNA consensus sequences from the clones (deposited in GenBank as Accession Nos. KC768321 and KC768322) were identical for both locations and showed 99 to 100% identity to several "Ca. L. solanacearum" sequences in GenBank (e.g., JN848753, JN84856, and HM246509). The OMB consensus sequences from the two tomato plants (deposited in GenBank as KC768329 and KC768330) were 100% identical to OMB sequences of Lso in GenBank (CP002371 and JN48754, respectively). To our knowledge, this is the first report of "Ca. Liberibacter solanacearum" associated with tomato crops in Honduras. This bacterium has caused millions of dollars in losses to the tomato industry in the United States, Mexico, and New Zealand (2,3,4). Serious damages to tomato crops due to "Ca. L. solanacearum" could expand throughout Central America, especially in those countries where B. cockerelli occurs. References: (1) J. M. Crosslin. Southwest. Entomol. 36:125, 2011. (2) L. W. Liefting et al. Plant Dis. 93:208, 2009. (3) J. E. Munyaneza et al. Plant Dis. 93:1076, 2009. (4) J. E. Munyaneza. Am. J. Pot. Res. 89:329, 2012.
2012年4月，在洪都拉斯几个省份种植的番茄（Lycopersicum esculentum）作物上，发现番茄严重受到番茄木虱（Bactericera cockerelli）侵害，植株出现疑似感染“番茄溃疡病菌（Candidatus Liberibacter solanacearum）”的症状。番茄木虱是马铃薯、番茄和其他茄科植物的一种严重害虫，也是“番茄溃疡病菌（Ca. L. solanacearum）”的传播媒介（参考文献1、2、3、4）。症状包括整体黄化、严重矮化、叶片卷曲、腋芽过度分枝以及叶片发紫和焦枯（参考文献2、3）。每个田地中出现症状的植株发病率在5%至50%之间。分别从位于埃尔帕拉伊索省丹利市和科马亚瓜省科马亚瓜市的两块受木虱侵害的商业田地里采集了番茄（品种为Pony）植株样本。分别采用十六烷基三甲基溴化铵（CTAB）缓冲液提取法，从50株有症状植株和20株无症状植株的叶片组织中提取总DNA（参考文献1、3）。使用针对该细菌16S rDNA（OA2和OI2c）和外膜蛋白基因（OMB 1482f和2086r）的引物对，通过PCR对DNA样本进行“番茄溃疡病菌（Ca. L. solanacearum）”检测（参考文献1、2）。50份有症状的番茄样本中, 10份（20%）使用两种引物对检测均呈“番茄溃疡病菌（Ca. L. solanacearum）”阳性，其余样本使用两种引物对检测均为阴性。20份无症状植株样本检测均未呈“番茄溃疡病菌（Ca. L. solanacearum）”阳性。每个引物对扩增出的来自两个植株样本（每个市一株）的DNA片段进行克隆，对四个扩增片段中的每一个片段的四个克隆进行测序。对克隆得到的16S rDNA共有序列（存入GenBank，登录号为KC768321和KC768322）进行BLASTn分析，结果表明两个地点的序列相同，与GenBank中多个“番茄溃疡病菌（Ca. L. solanacearum）”序列的同源性为99%至100%（例如JN848753、JN84856和HM246509）。来自两株番茄植株的OMB共有序列（存入GenBank，登录号为KC768329和KC768330）与GenBank中番茄溃疡病菌（Lso）的OMB序列100%相同（分别为CP002371和JN48754）。据我们所知，这是洪都拉斯番茄作物中首次报道与“番茄溃疡病菌（Ca. Liberibacter solanacearum）”相关的情况。这种细菌已给美国、墨西哥和新西兰的番茄产业造成了数百万美元的损失（参考文献2、3、4）。由“番茄溃疡病菌（Ca. L. solanacearum）”引起的番茄作物严重损害可能会在中美洲蔓延，特别是在番茄木虱存在的那些国家。参考文献：（1）J. M. Crosslin. Southwest. Entomol. 36:125, 2011.（2）L. W. Liefting等人. Plant Dis. 93:208, 2009.（3）J. E. Munyaneza等人. Plant Dis. 93:1076, 2009.（4）J. E. Munyaneza. Am. J. Pot. Res. 89:329, 2012.
