Fu S M, Hartung John, Zhou C Y, Su H N, Tan J, Li Z A
College of Plant Protection/Citrus Research Institute of Southwest University, Chongqing 400715, P. R. China, USDA-ARS Molecular Plant Pathology Laboratory, Beltsville, MD.
USDA-ARS Molecular Plant Pathology Laboratory, Beltsville, MD.
Plant Dis. 2015 Mar;99(3):320-324. doi: 10.1094/PDIS-01-14-0106-RE.
Huanglongbing (HLB), also known as citrus greening, is currently the most destructive citrus disease. Anatomical analyses of HLB-affected sweet orange were carried out by light and electron microscopy. As compared with healthy citrus, the phloem plasmodesmata were plugged with callose, and in some samples the phloem was collapsed. Chloroplast structures were deformed. Prophage sequences occupy a significant portion of the genome of 'Candidatus Liberibacter asiaticus' and have been used to distinguish strains from Yunnan and Guangdong provinces in China and Florida. Interestingly, a large number of possible putative phage particles were observed attached on the surface of 'Ca. L. asiaticus' cells in plants inoculated with strain FJ3 from Fujian Province, China. Phage particles have been observed previously only in periwinkle plants artificially inoculated in Florida with 'Ca. L. asiaticus' that carried the SC1-type prophage. PCR assays verified the presence of the SC1-type prophage sequences previously described from this bacterium in Florida in the FJ3 isolate. This is the first time that suspected phage particles have been observed in sweet orange trees infected with 'Ca. L. asiaticus.'
黄龙病（HLB），又称柑橘黄龙病，是目前最具破坏性的柑橘病害。利用光学显微镜和电子显微镜对感染黄龙病的甜橙进行了解剖分析。与健康柑橘相比，韧皮部胞间连丝被胼胝质堵塞，在一些样本中韧皮部出现塌陷。叶绿体结构变形。原噬菌体序列在“亚洲韧皮杆菌”（Candidatus Liberibacter asiaticus）的基因组中占很大比例，已被用于区分中国云南和广东省以及佛罗里达州的菌株。有趣的是，在接种了来自中国福建省的FJ3菌株的植物中，观察到大量可能的假定噬菌体颗粒附着在“亚洲韧皮杆菌”细胞表面。此前仅在佛罗里达州人工接种了携带SC1型原噬菌体的“亚洲韧皮杆菌”的长春花植物中观察到噬菌体颗粒。PCR检测证实了FJ3分离株中存在此前在佛罗里达州该细菌中描述的SC1型原噬菌体序列。这是首次在感染“亚洲韧皮杆菌”的甜橙树中观察到疑似噬菌体颗粒。
