How Woody Vegetatively-Propagated Materials are Placed
into LN2 Long-Term Storage
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Maintenance of woody vegetatively propagated perennials within orchards is a very costly method of germplasm preservation. Many times only two individuals are maintained for each clone, which could potentially be lost to disease or adverse environmental conditions.

Cryopreservation using a winter vegetative bud method is routinely used for preservation of Malus and some Prunus lines.

As a component of the National Plant Germplasm System (NPGS), the USDA-ARS Plant Genetic Resources Unit in Geneva, NY has the responsibility of acquisition, maintenance, distribution and characterization of Malus and Prunus germplasm. The long-term preservation site for the NPGS is NCGRP. The method used for cryopreservation of nodal sections from winterhardy scions has been termed the winter vegetative bud cryopreservation method and has been modified from reports by Sakai and co-workers and Stushnoff et al. (see references below).

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national map of location of plant and seed repositories

Scions are received from Geneva.

scion wood twig bundles

Scion wood twigs containing current season's growth are shipped over night to NCGRP for processing. Cold chilling units have been met (0°C for at least 72 hr).
bud section of a twig

Scions are cut into 1 bud 35 mm sections and dried to 25-30% moisture and held at -5°C.

Buds are packaged and slow cooled (1°C/hr) to -30°C and quickly placed into vapor phase LN2 for long-term storage (2-step cooling method).
small sections of buds
woman using drying oven
 These buds can then be grafted onto root stocks and a new tree can be grown.
apples on a branch

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Current Data

Approximately 2,000 Malus and 43 Prunus cerasus samples have been placed into long-term storage. Of these samples, presently 91% of Malus and 100% of Prunus cerasus have been tested for viability. NCGRP strives to maintain 60 viable buds in long-term storage.

References

Katano M., Ishihara A. and Sakai A. 1983. HortScience 18, 707-708.

Niino T., Koyama A., Shirata K., Ohuchi S., Suzuki M., and Sakai A. 1993. Journal of Sericultural Science, Japan. 62, 431-434.

Sakai A. 1960. Nature 185,393-394.

Sakai A. and Nishiyama Y. 1978. HortScience 13, 225-227.

Tyler N.J. and Stushnoff C. 1988. Canadian Journal of Plant Science 68, 1163-1167.

Tyler N.J. and Stushnoff C. 1988. Canadian Journal of Plant Science 68, 1169-1176.

Tyler N.J., Stushnoff C. and Gusta L.V. 1988. Plant Physiology 87, 201-205.

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