Case Report, Vegetos Vol: 31 Issue: 1
First report of Enterobacter Cloacae causing Stem Rot on Tobacco in China
*Corresponding Author : Guo YS
Academy of Guizhou tobacco Sciences, Guiyang 550083, P.R. China
Tel: +91- 8974236218
E-mail: [email protected]
Received: May 30, 2016 Accepted: December 21, 2017 Published: January 02, 2018
Citation: Zhang YC, Zhang JH, Shi ML, Wang HC, Guo YS, et al. (2018) First report of Enterobacter Cloacae causing Stem Rot on Tobacco in China. Vegetos 31:1. doi: 10.4172/2229-4473.1000372
Tobacco (Nicotiana tabacum L) is one of the most important economic and agricultural crops in China. Guizhou province produces nearly 30% of the total production. In the summer of 2010 and 2011, a sample with stem rot was collected in the commercial field in “Pan xian” of Guizhou province. The pathogen was identified as Enterobacter cloacae on the basis of morphology, sequence of 16S region of rDNA. This information provides new material for plant disease research in tobacco of China, This manuscript is the first report of E. cloacae causing stem rot on tobacco in China and the disease must be considered in existing disease management practices
Keywords: Stem rot; Tobacco; Enterobacter cloaca
A small piece (3 mm2) of symptomatic tissue from tobacco stem was placed in a sterile mortar and macerated in sterile distilled water with a pestle. A loopful of bacterial suspension was streaked onto NA medium . Plates were incubated at 28°C for 72 h. Single white, circular, shiny colonies were picked from the plates and transferred to NA medium. The isolate was Gram-negative, rod-shaped bacteria with the size of 0.4 ~ 0.8 μm×1.0 ~ 2.6 μm. The isolate was oxidase positive and levan positive, arginine-dihydrolase positive, and did not macerate potato discs. Also, the isolate was also non-fluorescent, grew at 37 and 4°C but not at 40°C, did not liquefy gelatin or starch and did not produce H2S.
The isolate was identified as Enterobacter cloacae on the basis of morphological, physiological, biochemical tests [2,3] and also the sequence of 16S rDNA region  and rpo B gene  amplified by PCR assay using primers. (F1:5′-AGAGTTGATCCATGGCTCAG- 3 ′ , R 1 : 5 ′ - AGAG T TGAT C C ATG G C TC AG - 3 ′ ) a n d ( F 2 : 5 ′ - A ACCAGT TC CGCGT TGGCC TG G - 3 ′ , R 2 : 5′-CCTGAACAACACGCTCGGA-3’) (5). Both the sequences of 16S rDNA region (GenBank Accession No. KC899076) and rpoB gene (GenBank Accession No. KM462827) were exactly match the sequence of two Enterobacter cloacae (Accession Nos: JN700133.1 , JN700140.1 and EU579858, GQ406571).
Four-week old tobacco plants (cv. K326) were inoculated by injection six potted plants using a bacterial suspension (108 CFU/ ml). Sterile water was injected into an additional five plants as a negative control treatment. The bacterial isolates caused rot on stem of inoculated plants.
Bacteria reisolated from the necrotic lesions using the technique previously described were identical to the original strains according to the morphological, cultural, and biochemical tests described above. Negative control plants inoculated with sterile distilled water did not show symptoms and no bacterial colonies were recovered from them. To our knowledge, this is the first report of E. cloacae causing stem rot on tobacco in China.
This work was financially supported by the Guizhou tobacco company project (Grant No. 201501) and Natural Science Foundation of Zhejiang Province, China (Grant No. LY17C140001).
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