|Clonal Propagated Crops|
Standard preservation of germplasm collections for many perennial crops is very costly and labor-intensive. The PGRU maintains three clonally propagated crops: apple, cold hardy grape, and tart cherry. There are typically two clones maintained for each accession in the Unit's vineyard and orchard. Due to the large number of accessions housed, maintenance costs are very high. In fact, it costs $75 to $100 each year to maintain each whole tree or vine in the field, but only about $1 to preserve it cryogenically. This, coupled with the collection's vulnerability to insect pests, diseases, and natural disasters, suggests that it is no longer prudent and cost effective to maintain the entire genetic diversity of these crops as whole plants.
It is important to note that these three crops are referred to as clonally propagated crops. In all three cases either a dormant bud or cutting is used to produce a plant identical to the original "mother". Johnny Appleseed has been replaced by bench grafting and budding techniques. Seeds and pollen are still important for breeding programs, but seeds would not be used to grow a Macintosh or Empire tree in your backyard.
Since 1992, 750 accessions have been cryopreserved from the Apple collection at the National Seed Storage Laboratory in Ft. Collins, CO, and an additional 250 have been cryopreserved in Geneva. Buds have been successfully recovered by grafting from over 90% of 600 accessions presently tested. These results, and those from ongoing recovery tests on 400 accessions stored in 1996, indicate cryopreservation may be a safe, cost-effective approach to enhance management of germplasm collections.