Location: Plant Germplasm Preservation ResearchTitle: Implementation of Citrus Shoot Tip Cryopreservation in the USDA-ARS National Plant Germplasm System Author
Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 1/11/2018
Publication Date: 3/26/2018
Citation: Volk, G.M., Jenderek, M.M., Walters, C.T., Bonnart, R.M., Shepherd, A.N., Skogerboe, D.M., Hall, B.D., Moreland, B.L., Krueger, R., Polek, M. 2018. Implementation of Citrus Shoot Tip Cryopreservation in the USDA-ARS National Plant Germplasm System. Meeting Abstract. 20.
Interpretive Summary: n/a
Technical Abstract: The USDA-ARS National Plant Germplasm System (NPGS) maintains 540 Citrus cultivars and crop wild relatives as duplicate clones in a screenhouse at the National Clonal Germplasm Repository for Citrus and Dates (NCGRCD) in Riverside, California. These 540 accessions are pathogen-tested and apparently free of all known graft-transmissible pathogens. An additional 634 citrus and citrus relative trees are maintained by the NCGRCD and the University of California, Riverside, in greenhouses until sanitation for pathogens can be completed. Between 2012 and 2017, a total of 451 of the pathogen-tested citrus accessions were cryoprocessed at the NCGRCD and the National Laboratory for Genetic Resources Preservation (NLGRP) in Fort Collins, Colorado. Vegetative budwood was collected and sent to NLGRP. A minimum of 170 shoot tips from each accession were excised from surface-sterilized budwood, which were then cryopreserved using a PVS2 droplet-vitrification technique. Viability was assessed by micrografting 10 liquid nitrogen-exposed shoot tips onto in vitro grown ‘Carrizo’ seedling rootstock. The remaining shoot tips were placed into long-term liquid nitrogen storage. Of the 451 Citrus and crop wild relative accessions cryoprocessed, 354 accessions had regrowth levels of 40% or greater, 17 had 0% regrowth, 47 had viability levels between 10 and 30%, and 33 had endogenous contaminants. This large-scale effort has revealed that shoot tip cryopreservation can be successfully scaled-up to secure the NPGS Citrus collection.