RESEARCH TO DEVELOP STRATEGIES AND TECHNOLOGIES FOR PRESERVING PLANT GENETIC DIVERSITY IN EX SITU GENEBANKS
Location: Plant Germplasm Preservation Research Unit
Title: Cryopreservation of citrus for long-term conservation
Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: July 20, 2012
Publication Date: November 19, 2012
Citation: Volk, G.M., Bonnart, R.M., Shepherd, A., Krueger, R., Lee, R.F. 2012. Cryopreservation of citrus for long-term conservation. XII International Citrus Congress, November 18 - 23, 2012, Valencia , Spain. Meeting Abstract. Paper No. S01O02.
More than 850 varieties of Citrus, Fortunella, and Citrus-related species are maintained within the USDA-ARS National Plant Germplasm System and the University of California Citrus Variety Collection. These genetic resources are held within duplicated field, screenhouse, and greenhouse collections. Plant materials are at risk of disease infestations, abiotic stresses, and natural disasters. We have developed a cryopreservation method by which we can back up Citrus genetic resources for the long term at liquid nitrogen temperatures. We excise shoot tips directly from greenhouse or screenhouse source plants, surface sterilize, and then treat with cryoprotectants. These solutions dehydrate and allow the shoot tips to survive liquid nitrogen exposure. Plants are recovered by micrografting thawed shoot tips onto ‘Carrizo’ seedling rootstocks. Plants representing diverse species exhibit a high regrowth (more than 50%), and can be transferred to greenhouse conditions within months. Cryopreserved plants did not revert to a juvenile state. Accessions of C. aurantifolia, C. clementina, C. celebica, and C. paradisi all flowered within 13 to 15 months after cryoexposure. These methods are also applicable for disease eradication using cryotherapy techniques.