Preserving plant tissues for secondary metabolite estimation and other bioassays requires careful handling and storage to maintain the integrity of the samples. Here are some steps to preserve different plant tissues:

1. Harvesting: Collect plant tissues at the appropriate stage of growth and at the desired time of day. Use sharp, sterile tools to minimize damage to the tissue.

2. Cleaning: Remove any dirt, debris, or damaged parts from the harvested plant tissues. Rinse gently with distilled water if necessary.

3. Drying: Depending on the type of tissue, drying methods may vary. For leaves and flowers, air-drying in a well-ventilated area away from direct sunlight is often suitable. For fruits or seeds, drying in a dehydrator or oven at low temperatures can be used.

4. Freezing: If immediate processing is not possible, freezing can be an effective preservation method for many plant tissues. Flash-freezing in liquid nitrogen or dry ice is recommended to minimize cellular damage.

5. Grinding: Once dried or frozen, grind the plant tissues into a fine powder using a mortar and pestle or a mechanical grinder. This increases surface area and facilitates extraction of secondary metabolites.

6. Storage: Store the powdered plant tissue in airtight containers such as glass vials or plastic bags with minimal air exposure to prevent oxidation and moisture absorption. Label each container with relevant information such as sample name, date of collection, and tissue type.

7. Temperature control: To maintain stability and prevent degradation of secondary metabolites, store the samples at low temperatures (-20°C or lower) if possible. If long-term storage is required, consider using ultra-low temperature freezers (-80°C).

8. Avoid repeated freeze-thaw cycles: Minimize exposing samples to temperature fluctuations by dividing them into smaller aliquots before freezing so that only one portion needs to be thawed at a time.

9. Protection from light: Some secondary metabolites are light-sensitive and can degrade upon exposure. Store samples in opaque containers or wrap them in aluminum foil to protect them from light.

10. Documentation: Keep detailed records of the preservation process, including collection information, preservation methods, and storage conditions. This information will be useful for future reference and analysis.

It is important to note that different plant tissues may require specific preservation techniques, so it is recommended to consult scientific literature or seek guidance from experts in the field for tissue-specific protocols.

You can go for Plant Cryopreservation Method.