Abstract: The results of transmission electron microscope tests of the negative staining specimens of plant endophyte were comparatively studied to explore the ideal preparation methods of transmission microscope negative staining specimens of plant endophyte. Firstly, four methods were used to prepare endophyte suspension, such as direct scraping, double distilled water flushing, double distilled water flushing followed by centrifugal separation and re-suspension and double distilled water flushing followed by static placing. Then, 10 g/L phosphotungstic acid was applied for floating negative staining and the transmission electron microscope test was carried out. And finally, the morphological characteristics, the shape and the quantity of the pilus and the flagellum of the endophyte were used as indicators to assess the advantages and disadvantages of these extracting and processing methods. Results: (1) The original state of the direct scraping sample is better, but the background is heavy, and the surface of the cell is affected easily by impurities. (2) The sample background of the double distilled water flushing is better. (3) The sample of the double distilled water flushing followed by centrifugal separation and re-suspension, and the sample of the double distilled water flushing followed by static placing have a clear vision, uniform distribution, clean background and less impurity under the transmission electron microscope. But the morphology structure of endouphyte of the former one was more easily affected. Transmission electron microscopy is an important tool for endophyte research. However, it is necessary to choose sample processing methods based on the actual situation. Under strict control of the static time, double distilled water flushing followed by static placing with the negative staining technique can achieve better test results.

Key words: plant endophyte, transmission electron microscope, negative staining