ABSTRACT
This article was aimed to study the dynamics of biocontrol endobacteria in roots, stems and leaves of Panax ginseng and soils adjacent roots. Gradient screening and root irrigation methods were used to develop Rif-resistance bacteria and inoculation. Dilution plate method was used to count the number of them in roots, stems and leaves of P. ginseng and soils adjacent roots. The results showed that bacteria which can endure 120 μg·mL-1 Rif was developed, and no change was found on their antagonistic activity against A lternaria panax Whetz and Phytophthora cactorum. In roots and stems of P. ginseng, ge15 and ge25 showed the highest number in the initial.Then, populations of ge15 and ge25 in ginseng roots and stems decreased to a stable status gradually. In ginseng leaves, populations of ge15 and ge25 increased to the highest 3 days after inoculation, then, populations of them were decreased and kept at certain concentration. In ginseng rhizosphere soil, populations of ge15 showed reciprocating change, and which of ge25 showed increase initial, and then decrease to a stable status. It was concluded that endobacteria can keep a certain population in ginseng roots, stems, and leaves. Biocontrol agents based on them will be helpful for ginseng diseases controlling in the field.
ABSTRACT
Background & objectives: Wolbachia are common intracellular bacteria that are found in arthropods and nematodes. These endosymbionts are transmitted vertically through host eggs and alter host biology in diverse ways, including the induction of reproductive manipulations, such as feminization, parthenogenesis, male killing and sperm-egg incompatibility. Since they can also move horizontally across species boundaries, Wolbachia is gaining importance in recent days as it could be used as a biological control agent to control vector mosquitoes or for paratransgenic approaches. However, the study of Wolbachia requires sophisticated techniques such as PCR and cell culture facilities which cannot be affordable for many laboratories where the diseases transmitted by arthropod vectors are common. Hence, it would be beneficial to develop a simple method to detect the presence of Wolbachia in arthropods. Method: In this study, we described a method of staining Wolbachia endobacteria, present in the reproductive tissues of mosquitoes. The reliability of this method was compared with Gram staining and PCR based detection. Results: The microscopic observation of the Gimenez stained smear prepared from the teased ovary of wild caught and Wolbachia (+) Cx. quinquefasciatus revealed the presence of pink coloured pleomorphic cells of Wolbachia ranging from cocci, comma shaped cells to bacillus and chain forms. The ovaries of Wolbachia (–) cured mosquito did not show any cell. Although Gram’s staining is a reliable differential staining for the other bacteria, the bacterial cells in the smears from the ovaries of wild caught mosquitoes did not take the stain properly and the cells were not clearly visible. The PCR amplified product from the pooled remains of wild caught and Wolbachia (+) Cx. quinquefasciatus showed clear banding, whereas, no banding was observed for the negative control (distilled water) and Wolbachia (–) Cx. quinquefasciatus. Interpretation & conclusion: The Gimenez staining technique applied, could be used to detect the members of the endobacteria Wolbachia easily, even in a simple laboratory without any special facilities or even in the field condition and for handling large number of samples in a shorter duration.