Chen X F, Zhang H L, Chen J
Laboratory of Biochemistry and Molecular Biology, School of Marine Sciences, Ningbo University, Ningbo, 315211, China, and Ningbo Academy of Inspection and Quarantine, Ningbo, 315012, China.
Ningbo Academy of Inspection and Quarantine.
Plant Dis. 2015 Jan;99(1):155. doi: 10.1094/PDIS-09-14-0916-PDN.
A bacterial pathogen, Dickeya solani, emerged as a major threat to potato (Solanum tuberosum) production in Europe in 2004 and has spread to many potato-growing regions via international trade. In December 2013, soft rot symptoms were observed in hyacinth (Hyacinthus orientalis) bulbs imported from the Netherlands into China at Ningbo Port. Diseased bulbs gave off an offensive odor. The base and internal parts of diseased bulbs rotted, and the margins of diseased tissues showed brown discoloration. Isolation on nutrient agar glucose (NAG) medium resulted in dominating colonies of characteristic "fried egg" morphology (1). One colony was chosen for further investigation and tentatively named "isolate 6165-3." Under microscopic visualization after gram stain, the cells of isolate 6165-3 were gram-negative, motile, and rod shaped. The isolate was then identified as a member of genus Dickeya using the Biolog GN microplate. The 16S rRNA, recA, and dnaX sequences of isolate 6165-3 were subsequently determined and deposited in GenBank with accession numbers KM405240, KM405241, and KM405242, sharing 99% (16S rRNA), 100% (recA), and 100% (dnaX) nucleotide identity with those of known D. solani isolates, respectively. By this means, the isolate 6165-3 was identified as D. solani (1,2). To confirm the pathogenicity of the isolate, four plants each of 30-day-old hyacinth, 14-day-old potato, and 60-day-old moth orchid (Phalaenopsis amabilis) were inoculated with suspensions of the isolate with a concentration of 10 CFU/ml in sterile water by stabbing. Plants were incubated in a climate chamber at 28°C during the day and 24°C during the night with a relative humidity of 93% and a photoperiod of 12/12 h. Plants inoculated with sterile water were included as negative controls. After 2 or 3 days, typical symptoms such as water-soaked lesions and soft rot developed around the inoculation point, while the negative controls remained symptomless. Koch's postulates were fulfilled by re-isolating bacteria from lesions, which had identical sequence and morphology characters with the inoculated isolate. This is the first report of intercepted D. solani on hyacinth bulbs imported from the Netherlands into China, indicating that D. solani can spread via hyacinth. Further spread of the pathogen into potato production might lead to immeasurable economic consequences for China. References: (1) P. F. Sarris et al. New Dis. Rep. 24:21, 2011. (2) J. M. van der Wolf et al. Int. J. Syst. Evol. Microbiol. 64:768, 2014.
2004年，一种细菌性病原菌——索拉尼果胶杆菌（Dickeya solani）成为欧洲马铃薯（Solanum tuberosum）生产的主要威胁，并通过国际贸易传播到许多马铃薯种植地区。2013年12月，在从荷兰进口到中国宁波港的风信子（Hyacinthus orientalis）种球上观察到软腐症状。患病种球发出难闻气味。患病种球的基部和内部组织腐烂，患病组织边缘出现褐色变色。在营养琼脂葡萄糖（NAG）培养基上分离得到具有特征性“煎蛋”形态的优势菌落（1）。挑选一个菌落进行进一步研究，并暂定名为“分离株6165 - 3”。革兰氏染色后显微镜观察发现，分离株6165 - 3的细胞为革兰氏阴性、具运动性且呈杆状。随后使用Biolog GN微孔板将该分离株鉴定为果胶杆菌属（Dickeya）的成员。随后测定了分离株6165 - 3的16S rRNA、recA和dnaX序列，并将其保藏于GenBank，登录号分别为KM405240、KM405241和KM405242，它们与已知索拉尼果胶杆菌分离株的相应序列分别具有99%（16S rRNA）、100%（recA）和100%（dnaX）的核苷酸同一性。通过这种方法，分离株6165 - 3被鉴定为索拉尼果胶杆菌（1,2）。为了确认该分离株的致病性，用浓度为10 CFU/ml的无菌水悬浮液通过针刺接种30日龄风信子、14日龄马铃薯和60日龄蝴蝶兰（Phalaenopsis amabilis）各四株。将接种无菌水的植株作为阴性对照。2或3天后，接种点周围出现典型症状，如水浸状病斑和软腐，而阴性对照无症状。通过从病斑中重新分离出与接种分离株具有相同序列和形态特征的细菌，科赫法则得以满足。这是首次报道从荷兰进口到中国的风信子种球上截获索拉尼果胶杆菌，表明索拉尼果胶杆菌可通过风信子传播。该病原菌进一步传播到马铃薯生产中可能会给中国带来不可估量的经济后果。参考文献：（1）P. F. Sarris等人，《新疾病报道》24:21，2011年。（2）J. M. van der Wolf等人，《国际系统与进化微生物学杂志》64:768，2014年。
