Cryopreservation: Freezing Plant Tissues
AbstractCryopreservation—storing seeds in ultra-cold liquid nitrogen—is one method for maintaining plant genetic stocks in seed banks. Can seeds withstand a really deep freeze and still germinate?
ObjectiveInvestigate how freezing seeds for different amounts of time affects their germination rate.
IntroductionScientists have been using cryopreservation to build a "living" archive of seed genes. Some of these frozen seeds are kept in storage in the event of natural disasters that may wipe out an important crop. The question remains about seed viability and how long seeds can remain in a frozen state and still germinate to produce a healthy plant. In this science fair project, you will investigate how freezing seeds affects their ability to germinate.
Terms and ConceptsYou should understand the difference between these two areas of study: cryopreservation and cryobiology.
You will need to understand seed structure and germination to understand what impact cryopreservation will have on the seed.
You should also understand exactly what happens to plant tissues when seeds are frozen. What is the process for freezing plant tissue for preservation? What are some of the disadvantages/risks of this process?
BibliographyWhat is cryobiology and cryopreservation:
- Wikipedia Contributors. (2012, February 15). Cryopreservation. Wikipedia: The Free Encyclopedia. Retrieved November 14, 2014.
- Wolfe, J. and Bryant, G. (1999). Cryobiology and anhydrobiology of cells. The University of New South Wales. Retrieved February 28, 2012.
- Hangarter, R. (n.d.). Corn Germination. Plants-In-Motion. Retrieved February 28, 2012.
- Towill, L.E. 2002. Cryopreservation Of Plant Germplasm: Introduction And Some Observations. Pp 3-21. In L.E. Towill And Y.P.S. Bajaj (EDS.)CRYOPRESERVATION Of Plant Germplasm Ii. Biotechnology In Agricultural And Forestry Series Vol 50. Springer, London.
Materials and Equipment
- Seeds; we suggest using the following seeds for this experiment (at least 5 of each type):
- Supersweet corn
- Lima bean
- Cabbage, radish, broccoli (choose one)
- Access to a lab with liquid nitrogen
- Petri dishes, available from Carolina Biological, item #: 741250
- Cotton rolls, available from Carolina Biological, item #: 712635
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- Suspend the seeds in liquid nitrogen. You should test at least four different time durations in the liquid nitrogen. You should also test at least five of each of the seed types in each of your experiments. Some time duration suggestions:
- Experiment 1: 1 day
- Experiment 2: 2 days
- Experiment 3: 3 days
- Experiment 4: 4 days
- After the appropriate length of time, remove the seeds from the liquid nitrogen.
- Prepare the petri dishes for germination. Cut the cotton slightly smaller than the diameter of the petri dish. Saturate the cotton in the petri dish with water and allow the dish to drain for 5 minutes as excess water will literally drown the seeds.
- Place the seeds in the petri dish and place them in the oven at about 70°–80° F.
- Observe and record the rate of germination for each of the seeds every 24 hours until they are ready for planting.
- Which time duration in the liquid nitrogen led to the best germination results?
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