Oolong tea and LR-White resin: a new method of plant sample preparation for transmission electron microscopy.

Simplifying sample processing, shortening the sample preparation time, and adjusting procedures to suitable for new health and safety regulations, these issues are the current challenges which electron microscopic examinations need to face. In order to resolve these problems, new plant tissue sample processing protocols for transmission electron microscopy should be developed. In the present study, we chose the LR-White resin-assisted processing protocol for the ultrastructural observation of different types of plant tissues. Moreover, we explored Oolong tea extract (OTE) as a substitute for UA in staining ultrathin sections of plant samples. The results revealed that there was no significant difference between the OTE double staining method and the traditional double staining method. Furthermore, in some organelles, such as mitochondria in root cells of tomatoes and chloroplast in leaf cells of watermelons, the OTE double staining method achieved little better results than the traditional double staining method. Therefore, OTE demonstrated good potentials in replacing UA as a counterstain on ultrathin sections. In addition, sample preparation time was significantly shortened and simplified using LR-White resin. This novel protocol reduced the time for preparing plant samples, and hazardous reagents in traditional method (acetone and UA) were also replaced by less toxic ones (ethanol and OTE). Lay description The present method of sample process for observation by transmission electron microscopy was faced some issues, such as simplifying sample processing, shortening the sample preparation time, and adjusting procedures to suitable for new health and safety regulations. To resolve these problems, our team developed a new sample processing protocols for plant tissues. During the process, we chose safer, more timesaving and effort and easier to operate resin. On the other hand, we used a tea powder (Oolong tea extract) solution to replace a high toxicity and radioactivity reagent (uranyl acetate) during the staining procedure. At the end, the results showed that the samples could be observed equal or even clearer details compared with the conventional method. So we considered that this new method could be alternative process which became more save time and effort, safer and easier.