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Research Project: Innovations that Improve the Efficiency and Effectiveness of Managing and Preserving Ex Situ Plant Germplasm Collections

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Title: Probabilistic viability calculations for cryopreserving vegetatively propagated collections in genebanks

Author
item Volk, Gayle
item Henk, Adam
item Jenderek, Maria
item Richards, Christopher

Submitted to: Genetic Resources and Crop Evolution
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/12/2016
Publication Date: 11/5/2016
Citation: Volk, G.M., Henk, A.D., Jenderek, M.M., Richards, C.M. 2016. Probabilistic viability calculations for cryopreserving vegetatively propagated collections in genebanks. Genetic Resources and Crop Evolution. doi:10.1007/S10722-016-0460-6.

Interpretive Summary: Genebank collections of vegetatively propagated fruits and vegetables are difficult and expensive to maintain. They are usually kept as plants in the field or greenhouse which makes them vulnerable to pathogens and climatic threats. International genebank standards recommend that vegetatively propagated collections be securely backed-up at secondary sites using in vitro culture or through the use of cryopreservation. Cryopreservation is often the preferred back-up option for these collections because materials can be maintained for low annual costs once the initial processing is complete. The process of cryopreservation is time- and labor-intensive, thus making it necessary for curators to carefully consider the number of samples that will be processed. This work provides a calculator tool and tables that can be used by genebank managers to determine the number of samples needed to be processed in order to have a defined confidence in retrieving viable explants. This information will allow gene bank managers to determine the trade-offs between investments in processing labor vs. long term viability. In addition, the plant cryobanking literature was surveyed to summarize and compare the sample processing practices that have been implemented within genebanks. Using our calculator tool, the predicted number of viable explants in each accession within these cryobanked collections was calculated based on the published viability levels and number of explants processed. Implementation of the proposed tools and tables will allow genebank managers to determine if shifts in their current methods could result in more efficient back-up procedures.

Technical Abstract: Vegetatively propagated plant collections within genebanks are vulnerable to threats when they are maintained in field or greenhouse conditions. International genebanking standards recommend that these collections be securely backed-up at either secondary locations or by using in vitro culture or cryopreservation. A series of tools and tables were developed to assist genebank managers in determining the predicted number of viable explants after cryopreservation procedures have been employed based on the number of samples processed and the viability for a range of confidence levels (0.5, 0.75, 0.90, 0.95, and 0.99). In addition, critical viabilities were estimated which represent the minimal viability required to have at least one viable explant for a given number of explants stored per cryovial or tube. The plant cryobanking literature was surveyed to summarize the sample processing practices that have been implemented within genebanks. The number of explants predicted to be viable in each accession within these cryobanked collections was calculated based on the published viability levels and numbers of explants processed. Implementation of the proposed tools and tables will allow genebank managers to determine if shifts in their current methods could result in more efficient back-up procedures.