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Research Project: Plant and Microbial Genetic Resource Preservation and Quality Assessment

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Title: Cryopreserved storage of clonal germplasm in the USDA National Plant Germplasm System

Author
item Jenderek, Maria
item Reed, Barbara

Submitted to: In Vitro Cellular and Developmental Biology - Plants
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/27/2017
Publication Date: 6/5/2017
Citation: Jenderek, M.M., Reed, B.M. 2017. Cryopreserved storage of clonal germplasm in the USDA National Plant Germplasm System. In Vitro Cellular and Developmental Biology - Plants. doi:10.1007/s11627-017-9828-3.

Interpretive Summary: Vegetatively (clonally) propagated crops are an essential part of our food supply; they include staple food (potato, banana, sweet potato), industrial crops (sugarcane), berries and fruit (e.g., apricot, apple, cacao, citrus, pear, blueberry, strawberry, black- and raspberry), and other trees and shrubs (e.g., maple, willow, ash, pine, rose, magnolia, dogwood). Preserving clonal genetic resources is fundamental to maintain the crops’ variety in cultivation and support future cultivar development. The USDA-ARS, National Plant Germplasm System (NPGS) has several repositories spread over the U.S. that maintain, characterize and distribute clonal genetic resources for breeding/selection and research purposes. Preserving clonal plants is expensive, requires high labor and a lot of filed and greenhouse space. Storing fragments of plants in liquid nitrogen (-196oC) is a cost effective and a secure preservation method; however, the initial expense of introducing plants into liquid nitrogen is high, the cost of this storage system is minute in comparison to maintaining the genetic resources in filed, or in a greenhouse, or as tissue culture. Cryopreservation (storage in liquid nitrogen or its vapor) is carried out at the Plant and Animal Genetic Resources Preservation (PAGRP) Unit that is a part of the NPGS. Currently, over 3,900 unique accessions are backed up in liquid nitrogen providing a valuable security for these crops that cannot be stored as seed. Clonally propagated crops are vital to our economy, diet and lifestyle.

Technical Abstract: The U.S. Department of Agriculture-Agricultural Research Service (USDA-ARS), National Plant Germplasm System (NPGS) plant collections are a critical source of genetic diversity for breeding and selection of improved crops, including vegetatively propagated plants. Information on these collections is readily accessible to breeders and researchers on the internet from the Germplasm Resources Information Network (GRIN). The clonal collections are at risk for loss due in part to their genetic diversity that makes growing them in one location a challenge, but also because it is difficult to have duplicate collections without incurring great expense. The development of cryopreservation techniques provides a low maintenance form of security backup for these collections. National plant collections for vegetatively propagated crop plants and their wild relatives are maintained by the USDA-ARS, NPGS at 15 sites across the country. These sites include various combinations of field, greenhouse, screenhouse and in vitro collections. Cryopreserved backup collections in liquid nitrogen storage were instituted in the 1990s, increased greatly in the 2000s with the advent of new techniques, and are continuing today. Collections of dormant buds of temperate trees, shoot tips of in vitro cultures of many crops, embryonic axes of some large seeded or recalcitrant seeds are all part of the clonal backup storage system. Cryopreserved storage costs are initially similar to one year of field preservation, but the long-term costs are reduced to pennies per accession each year.