Secor G A, Rivera V V, Abad J A, Lee I-M, Clover G R G, Liefting L W, Li X, De Boer S H
Department of Plant Pathology, North Dakota State University, Fargo 58105, USA.
USDA, APHIS, Beltsville, MD 20705, USA.
Plant Dis. 2009 Jun;93(6):574-583. doi: 10.1094/PDIS-93-6-0574.
A new disease of potatoes, tentatively named zebra chip (ZC) because of the intermittent dark and light symptom pattern in affected tubers which is enhanced by frying, was first found in Mexico in 1994 and in the southwestern United States in 2000. The disease can cause severe economic losses in all market classes of potatoes. The cause of ZC has been elusive, and only recently has been associated with 'Candidatus Liberibacter' sp. Field samples of potato plants were collected from several locations in the United States, Mexico, and Guatemala to determine transmission to potato and tomato by grafting of ZC-infected scions and psyllid feeding. The disease was successfully transmitted, through up to three generations, by sequential top- and side-grafting ZC-infection scions to several potato cultivars and to tomato. The disease was also successfully transmitted to potato and tomato plants in greenhouse experiments by potato psyllids collected from potato plants naturally affected with ZC. Transmission electron microscopic observation of ZC-affected tissues revealed the presence of bacteria-like organisms (BLOs) in the phloem of potato and tomato plants inoculated by grafting and psyllid feeding. The BLOs were morphologically similar in appearance to BLOs associated with other plant diseases. Polymerase chain reaction (PCR) amplified 16S rDNA sequences from samples representing different geographic areas, including the United States, Mexico, and Guatemala, were almost identical to the 16S rDNA of 'Ca. L. solanacearum' previously reported from solanaceous plants in New Zealand and the United States. Two subclades were identified that differed in two single base-pair substitutions. New specific primers along with an innovative rapid PCR were developed. This test allows the detection of the bacteria in less than 90 min. These data confirm the association of 'Ca. L. solanacearum' with potatoes affected by ZC in the United States, Mexico, and Guatemala.
一种新的马铃薯病害，由于受感染块茎中出现间歇性的明暗症状模式（油炸后会更明显），暂命名为斑马薯片病（ZC），1994年首次在墨西哥发现，2000年在美国西南部发现。这种病害会给所有市场等级的马铃薯造成严重经济损失。斑马薯片病的病因一直难以确定，直到最近才发现与“李氏菌属”有关。从美国、墨西哥和危地马拉的多个地点采集了马铃薯植株的田间样本，以通过嫁接感染ZC的接穗和木虱取食来确定其对马铃薯和番茄的传播情况。通过将感染ZC的接穗依次进行顶接和侧接，成功地将这种病害传播给了多个马铃薯品种和番茄，传播代数多达三代。在温室试验中，从自然感染ZC的马铃薯植株上采集的马铃薯木虱也成功地将这种病害传播给了马铃薯和番茄植株。对受ZC影响的组织进行透射电子显微镜观察发现，通过嫁接和木虱取食接种的马铃薯和番茄植株的韧皮部中存在类细菌生物体（BLOs）。这些BLOs在形态上与其他植物病害相关的BLOs相似。聚合酶链反应（PCR）从代表不同地理区域（包括美国、墨西哥和危地马拉）的样本中扩增出的16S rDNA序列，与先前在新西兰和美国的茄科植物中报道的“番茄李氏菌”的16S rDNA几乎相同。鉴定出了两个亚分支，它们在两个单碱基对替换上存在差异。开发了新的特异性引物以及创新的快速PCR方法。该检测方法可在不到90分钟内检测出细菌。这些数据证实了“番茄李氏菌”与美国、墨西哥和危地马拉受ZC影响的马铃薯之间的关联。
