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

Invited Review


The US 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 during the last two decades 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, and embryonic axes of some large seeded or recalcitrant seeded plants are all part of the clonal backup storage system.


Cryopreservation Dormant buds Germplasm In vitro shoot tips 



This project was funded by USDA-ARS CRIS project 5402-21000-007-00D at the Plant and Animal Genetic Resources Preservation Unit, Fort Collins, CO and CRIS project 5358-21000-044-00D at the National Clonal Germplasm Repository, Corvallis, OR.

Mention of trade names or commercial products in this publication is solely for the purpose of providing specific information and does not imply recommendation or endorsement by the US Department of Agriculture.


  1. Abreu-Tarazi MF, Navarrete AA, Androete FD, Almeida CV (2010) Endophytic bacteria in long-term in vitro cultivated “axenic” pineapple microplants revealed by PCR-DGGE. World J Microbiol Biotechnol 26:555–560CrossRefGoogle Scholar
  2. Bairu MW, Aremu AO, van Staden J (2011) Somaclonal variation in plants: causes and detection methods. Plant Growth Regul 63:147–173CrossRefGoogle Scholar
  3. Bairu MW, Fennel CW, van Staden J (2006) The effect of plant growth regulators on somaclonal variation in Cavendish banana (Musa AAA cv. ‘Zelg’). Sci Hortic 108:347–351CrossRefGoogle Scholar
  4. Bairu MW, Strik WA, Doležal K, van Staden J (2008) The role of topolins in micropropagation and somaclonal variation of banana cultivars ‘Williams’ and ‘Grand Naine’ (Musa spp. AAA). Plant Cell Tissue Organ Cult 95:373–379CrossRefGoogle Scholar
  5. Bamberg JB, Martin MW, Abad J, Jenderek MM, Tanner J, Donnelly DJ, Nassar AMK, Veilleux RE, Novy RG (2016) In vitro technology at the US Potato Genebank. In Vitro Cell Dev Biol Plant 52:213–225CrossRefGoogle Scholar
  6. Bell RL, Reed BM (2002) In vitro tissue culture of pear: advance in techniques for micropropagation and germplasm preservation. Proc. 8th IS on Pear. Acta Hortic 596:412–418CrossRefGoogle Scholar
  7. Benson EE (1999) Plant conservation biotechnology. Taylor and Francis, LondonGoogle Scholar
  8. de Boucaud MT, Brison M (1995) Cryopreservation of germplasm of walnut (Juglans species). In: Bajaj YPS (ed) Biotechnology in agriculture and forestry. Springer, Berlin, pp 129–147Google Scholar
  9. Botkin DB, Saxe H, Araújo B, Betts R, Bradshaw HW, Cedhagen T, Chesson P, Dawson TP, Etterson JR, Faith DP, Ferrier S, Guisan A, Skjoldborg Hansen A, Hibert DW, Loehle C, Margules CH, New M, Sobel MJ, Stockwell DRB (2007) Forcasting the effects of global warming on biodiversity. BioScience 57:227–236Google Scholar
  10. Chang Y, Barker R, Reed BM (2000) Cold acclimation improves recovery of cryopreserved grass (Zoysia and Lolium sp.) CryoLetters 21:107–116PubMedGoogle Scholar
  11. Chang Y, Reed BM (1999) Extended cold acclimation and recovery medium alteration improve regrowth of Rubus shoot tips following cryopreservation. CryoLetters 20:371–376Google Scholar
  12. Dullinger S, Essl F, Rabittsch W, Erb K-H, Gengrich S, Haberl H, Hülber K, Jarošik V, Krausmann I, Kühn I, Pergl J, Pyšek P, Hulme PE (2013) Europe’s other debt crisis caused by long legacy of future extinction. PANS 110(18):7342–7347 Google Scholar
  13. Dullinger S, Gattringer A, Thuiller W, Moser D, Zimmermann NE, Guisan A, Willner W, Plutzar C, Leitner M, Mang T, Caccianiga M, Dirnböck T, Erti S, Fischer A, Lenior J, Svenning JCH, Psomas A, Schmatz DR, Silc U, Vittoz P, Hülber K (2012) Extinction debt of high-mountain plants under twenty-first century climate change. Nat Clim Chang 2:619–622CrossRefGoogle Scholar
  14. Dulloo ME, Ebert AW, Dussert S, Gotor E, Astroga C, Vasquez N, Rakotomalala JJ, Rabemiafara A, Eira M, Bellachew B, Omondi C, Engelman F, Anthony F, Watts J, Qamar Z, Snook L (2009) Cost efficency of cryopreservation as a long-term conservation method for coffee genetic resources. Crop Sci 49:2123–2138CrossRefGoogle Scholar
  15. Dulloo ME, Guarino L, Engelmann F, Maxted N, Newbury JH, Atterc F, Ford-Lloyd BV (1998) Complementary conservation strategies for the genus Coffea: a case study of Mascarene Coffea species. Genet Resour Crop Evol 45:565–579CrossRefGoogle Scholar
  16. Ellis D, Skogerboe D, Andre C, Hellier B, Volg G (2006) Implementation of garlic cryopreservation techniques in the National Plant Germplasm System. CryoLetters 27:99–106Google Scholar
  17. Folimonova SY, Robertson CJ, Garnsey SM, Gowda S, Dawson WO (2009) Examination of the responses of different genotypes of citrus to Huanglongbing (citrus greening) under different conditions. Phytopathology 99:1346–1354CrossRefPubMedGoogle Scholar
  18. Forsline PL, Towill LE, Waddell JW, Stushnoff C, Lamboy WF, McFerson JR (1998) Recovery and longevity of cryopreserved dormant apple buds. J Am Soc Hortic Sci 123:365–370Google Scholar
  19. Graca JD (1991) Citrus greening disease. Annu Rev Phytopathol 29:109–136CrossRefGoogle Scholar
  20. Groenendael JM, Klimeš L, Klimešová J, Hendriks RJJ (1996) Comparative ecology of clonal plants. Phil Trans R Soc Lond B 351:1331–1339CrossRefGoogle Scholar
  21. Grout BWW, Westcott RJ, Henshaw GG (1978) Survival of shoot meristems of tomato seedlings frozen in liquid nitrogen. Cryobiology 15:478–483CrossRefPubMedGoogle Scholar
  22. Hamill SD, Wasmund K, Smith M, Eccleston K, MsKay D (2005) Endogenous bacteria isolated from banana meristems during tissue culture initiation: problems and potential. In: Benett IJ, Bunn E, Clarke H, McComb JA (eds) Contributing to a Sustainable Future. Proc of the Australian Branch IAPTC & B, Perth, pp 101–111Google Scholar
  23. Harada T, Inaba A, Yakuwa T, Tamura T (1985) Freeze-preservation of apices isolated from small heads of brussels sprouts. Hortscience 20:678–680Google Scholar
  24. Harvengt L, MeierDinkel A, Dumas E, Collin E (2004) Establishment of a cryopreserved gene bank of European elms. Can Res For Res 34:43–55CrossRefGoogle Scholar
  25. Heywood VH, Iriondo JM (2003) Plant conservation: old problems, new perspectives. Biol Conserv 113:321–335CrossRefGoogle Scholar
  26. Hirai D, Shirai K, Shirai S, Sakai A (1998) Cryopreservation of in vitro-grown meristems of strawberry (Fragaria x ananassa Duch.) by encapsulation-vitrification. Euphytica 101:109–115CrossRefGoogle Scholar
  27. Huang CM, Li YR, Ye YP (2003) Minimizing phenol pollution in sugarcane stem apical meristem culture. Sugar Tech 5:297–300CrossRefGoogle Scholar
  28. Jahn OL, Westwood MN (1982) Maintenance of clonal germplasm. Hortscience 17:122Google Scholar
  29. Jarret RL, Florkowski WJ (1990) In vitro active vs. field genebank maintenance of sweet potato germplasm: major costs and considerations. Hortscience 25:141–146Google Scholar
  30. Jenderek MM, Ambruzs B, Tanner J, Holman G, Ledbetter C, Postman J, Ellis D, Leslie C (2014) Extending the dormant bud cryopreservation method to new tree species. Proc IInd IS on Plant Cryopreservation. Acta Hortic 1039:133–136Google Scholar
  31. Jenderek MM, Forsline P, Postman J, Stover E, Ellis D (2011) Effect of geographical location, year and cultivar on survival of Malus sp. dormant buds stored in vapor of liquid nitrogen. Hortscience 46:1230–1234Google Scholar
  32. Jenderek MM, Tanner JD, Ambruzs BD, West M, Postman JD, Hummer KE (2017) Twig pre-harvest temperature significantly influences effective caryopreservation of Vaccinium dormant buds. Cryobiology 74:154–159CrossRefPubMedGoogle Scholar
  33. Kartha K (1985) Cryopreservation of plant cells and organs, Vol.1. CRC, Florida, p 276Google Scholar
  34. Kartha KK, Leung NL, Gamborg OL (1979) Freeze-preservation of pea meristems in liquid nitrogen and subsequent plant regeneration. Plant Sci Lett 15:7–15CrossRefGoogle Scholar
  35. Katano M, Ishihara A, Sakai A (1983) Survival of dormant apple shoot tips after immersion in liquid nitrogen. Hortscience 18:707–708Google Scholar
  36. Keller ERJ, Kaczmarczyk A, Senula A (2008) Cryopreservation for plant genebanks–a matter between high expectations and cautious reservation. CryoLetters 29:53–62Google Scholar
  37. Kerns HR, Meyer MM Jr (1986) Tissue culture propagation of Acer freemanii using thidiazuron to stimulate shoot proliferation. Hortscience 21:1209–1210Google Scholar
  38. Khan SA, Rashid H, Chaudhary MF, Chaudhary Z (2007) Optimization of explant sterilization condition in sugarcane cultivars. Pakistan J Agric Res 20:119–123Google Scholar
  39. Kovalchuk I, Turtiev T, Muckhitdova Z, Frolov S, Reed B, Kairova G (2014) New techniques for rapid cryopreservation of dormant vegetative buds. Acta Hortic 1039:137–146CrossRefGoogle Scholar
  40. Kumari R, Verma DK (2001) Development of micropropagation protocols for sugarcane (Saccharum officinarum L.)–a review. Agric Rev 22:87–94Google Scholar
  41. Kuoksa T, Hohtola A (1991) Freeze preservation of buds from Scots pine trees. Plant Cell Tissue Organ Cult 27:89–93CrossRefGoogle Scholar
  42. Lorenzo JC, Angels ML, Pelaez O, Gonzalez A, Cid M, Iglesias A, Gonzalez B, Escalona M, Espinoza P, Borrato C (2001) Sugarcane micropropagation and phenolic excretion. Plant Cell Tissue Organ Cult 65:1–8CrossRefGoogle Scholar
  43. Lux-Endrich A, Treautter D, Feucht W (2000) Influence of nutrients and carbohydrate supply on the phenolcomposition of apple shoot culture. Plant Cell Tissue Organ Cult 60:15–21CrossRefGoogle Scholar
  44. Matsumoto T, Mochida K, Itamura H, Sakai A (2001) Cryopreservation of persimmon (Diospyrus kakai Thumb.) by vitrification of dormant shoot tips. Plant Cell Rep 20:398–402CrossRefGoogle Scholar
  45. Moriguchi T (1995) Cryopreservation and minimum growth storage of pear (Pyrus species). In: Bajaj YPS (ed) Biotechnology in agriculture and forestry. Springer, Berlin, pp 114–128Google Scholar
  46. Mneney E, Ndakidemi P (2014) Effects of ascorbic acid in controlling lethal browning in in vitro culture of Brahylaena huillensis using nodal segments. Am J Plant Sci 5:187–191CrossRefGoogle Scholar
  47. Nehra NS, Katha KK, Stushnoff C, Glies KL (1992) The influence of plant growth regulator concentrations and callus age on somaclonal variation in callus culture regenerants of strawberry. Plant Cell Tissue Organ Cult 29:257–268CrossRefGoogle Scholar
  48. Nicotra AB, Atkin OK, Bonser SP, Davidson AM, Finnegan EJ, Mathesius PP, Purugganan MD, Richards CL, Valladeres F, van Kleunen M (2010) Plant phenotypic plasticity in a changing climate. Trends Plant Sci 15:684–692CrossRefPubMedGoogle Scholar
  49. Niino T (1995) Cryopreservation of germplasm of mulberry (Morus species). In: Bajaj YPS (ed) Biotechnology in agriculture and forestry. Springer-Verlag, Berlin, pp 102–113Google Scholar
  50. Normah MN, Cyde MM, Cho EG, Ramantha Rao V (2002) Ex situ conservation of tropical rare fruit species. Proc. IS on Trop. & Subtrop. Fruits Acta Hortic 575:221–230CrossRefGoogle Scholar
  51. Orlikowska T, Nowak K, Reed BM (2017) Bacteria in the plant tissue culture environment. Plant Cell Tissue Organ Culture 128:487–508CrossRefGoogle Scholar
  52. Ozyigit II, Kahraman MV, Ercan O (2007) Relation between explant age, total phenols and regeneration response in tissue cultured cotton (Gossypium hirsutum L.) Afr J Biotechnol 6:3–9Google Scholar
  53. Panis B, Vandenbranden K, Schoofs H, Swennen R (1998) Conservation of banana germplasm through cryopreservation. Acta Hortic 461:515–521CrossRefGoogle Scholar
  54. Pence VC (2010) The possibilities and challenges of in vitro methods for plant conservation. Kew Bull 65:539–547CrossRefGoogle Scholar
  55. Pence VC (2011) Evaluating costs for in vitro propagation and preservation of endangered plants. In Vitro Cell Dev Biol Plant 47:176–187CrossRefGoogle Scholar
  56. Ploetz RC (2006) Fusarium wilt of banana is caused by several pathogens referred to as Fusarium oxysporum f. sp. cubense. Phytopathology 96:653–656CrossRefPubMedGoogle Scholar
  57. Postman J, Hummer K, Stover E, Krueger R, Forsline P, Grauke LJ, Zee F, Ayala-Silva T, Irish B (2006) Fruit and nut genebanks in the US National Plant Germplasm System. Hortscience 41:1188–1194Google Scholar
  58. Qin TH, Zhou ZL, Wu CW (1997) Study on phenol pollution in tissue culture of sugarcane. Sugarcane 4:12–14Google Scholar
  59. Reed BM (1999) The in vitro genebank of temperate fruit and nut crops at the National Clonal Germplasm Repository-Corvallis. In: Engelmann F (ed) Management of field and in vitro germplasm collections. Proceedings of a Consultation Meeting, CIAT, Cali, Columbia. International Plant Genetic Resources Institute, Rome, Italy, 15–20 January 1996Google Scholar
  60. Reed BM (2001) Implementing cryogenic storage of clonally propagated plants. CryoLetters 22:97–104PubMedGoogle Scholar
  61. Reed BM (2008) Cryopreservation - Practical consideration, pp 10-13. In: Plant Cryopreservation. A practical guide. Springer Science and Business Media LLC, New YorkGoogle Scholar
  62. Reed BM (2013) Antioxidant and cryopreservation, the new normal? Proc 2nd Int Symp Plant Cryopreservation Acta Hortic 1039:41–46Google Scholar
  63. Reed BM, Brennan RM, Benson EE (2000) Cryopreservation: an in vitro method for conserving Ribes germplasm in international gene banks. In: Engelmann F, Takagi H (eds) Cryopreservation of tropical germplasm: current research progress and application. Japan International Research Center for Agricultural Sciences and International Plant Genetic Resources Institute, Rome, pp 470–473Google Scholar
  64. Reed BM, Chang Y (1997) Medium- and long-term storage of in vitro cultures of temperate fruit and nut crops. In: Razdan MK, Cocking EC (eds) Conservation of plant genetic resources in vitro. Science, Enfield, pp 67–105Google Scholar
  65. Reed BM, DeNoma J, Luo J, Chang Y, Towill L (1998) Cryopreservation and long-term storage of pear germplasm. In Vitro Cell Dev Biol Plant 34:256–260CrossRefGoogle Scholar
  66. Reed BM, Engelmann F, Dulloo E, Engels J (2004a) Technical Guidelines for the Management of Field and In vitro Germplasm Collections. IPGR Handbooks for Genebanks no 7. International Plant Genetic Resources Institute/Food Agriculture Organization/System-wide Genetic Resources Programme, Rome, ItalyGoogle Scholar
  67. Reed B, Gupta S, Uchendu E (2013) In vitro genebanks for preserving tropical diversity. In: Normah MN, Chin HF, Reed BM (eds) Conservation of tropical plant species. Springer, New York, pp 77–106CrossRefGoogle Scholar
  68. Reed BM, Hummer K (1995) Conservation of germplasm of strawberry (Fragaria species). In: Bajaj YPS (ed) Biotechnology in agriculture and forestry: cryopreservation of plant germplasm I. Springer, Berlin, pp 354–370CrossRefGoogle Scholar
  69. Reed BM, Lagerstedt HB (1987) Freeze preservation of apical meristems of Rubus in liquid nitrogen. Hortscience 22:302–303Google Scholar
  70. Reed BM, Meier-Dinkel A, Kovalchuk I, Pluta S, Benson EE (2004b) Evaluation of critical points in technology transfer of cryopreservation protocols to international plant conservation laboratories. CryoLetters 25:341–352PubMedGoogle Scholar
  71. Reed BM, Okut N, D’Achino J, Narver L, DeNoma J (2003) Cold storage and cryopreservation of hops (Humulus L.) shoot cultures through application of standard protocols. CryoLetters 24:389–396PubMedGoogle Scholar
  72. Reed BM, Schumacher L, Wang N, D’Achino J, Barker RE (2006) Cryopreservation of bermudagrass germplasm by encapsulation dehydration. Crop Sci 46:6–11CrossRefGoogle Scholar
  73. Reinhold-Hurek B, Hurek T (2011) Living inside plants: bacterial endophytes. Curr Opin Plant Biol 14:435–443CrossRefPubMedGoogle Scholar
  74. Ryynänen L (1996) Survival and regeneration of dormant sliver birch buds stored at super-low temperatures. Can J For Res 26:617–623CrossRefGoogle Scholar
  75. Sahijram L, Soneji JR, Bollamma KT (2003) Analyzing somaclonal variation in micropropagated banana (Musa spp.) In Vitro Cell Dev Biol Plant 39:551–556CrossRefGoogle Scholar
  76. Sakai A (1960) Survival of the twig of woody plants at −196°C. Nature 185:392–394Google Scholar
  77. Sakai A (1984) Cryopreservation of apical meristems. Hortic Rev 6:357–372Google Scholar
  78. Sakai A (1985) Cryopreservation of shoot-tips of fruit trees and herbaceous plants. In: Kartha KK (ed) Cryopreservation of plant cells and tissues. CRC Press, Boca Raton, pp 135–170Google Scholar
  79. Sakai A, Nishiyama Y (1978) Cryopreservation of winter vegetative buds of hardy fruit trees in liquid nitrogen. Hortscience 13:225–227Google Scholar
  80. Sakai A, Yamakawa M, Sakata D, Harada T, Yakuwa T (1978) Development of a whole plant from an excised strawberry runner apex frozen to −196 C. Low Temp Sci Ser 36:31–38Google Scholar
  81. Sarasan V, Crips R, Ramsey MM, Atherton C, McMichen M, Prendergast G, Rowntree JK (2006) Conservation in vitro of threatened plants–progress in the past decade. In Vitro Cell Dev Biol Plant 42:206–214Google Scholar
  82. Schafer-Menuhr A (1996) Refinement of cryopreservation techniques for potato. Final report for the period Sept. 1991–1993. IPGRI Report No. XXX. International Plant Genetic Resources Institute, RomeGoogle Scholar
  83. Seufferheld MJ, Stushnoff C, Forsline PL, Gonzalez GHT (1999) Cryopreservation of cold-tender apple germplasm. J Amer Soc Hortic Sci 124:612–618Google Scholar
  84. Shimelis D (2015) Effects of polyvinylpyrrolidone and activated charcoal to control effects of phenolic oxidation on in vitro culture establishment stage of micropropagation of sugarcane (Saccharum officinarum L.) J Appl Sci Res 2:52–57Google Scholar
  85. Skirvin RM, McPheeters KB, Norton M (1994) Sources and frequency of somaclonal variation. Hortscience 29:1232–1237Google Scholar
  86. Stuefer JF (1994) Potential and limitations of current concepts regarding the response of clonal plants to environmental heterogenity. Vegetatio 127:55–70CrossRefGoogle Scholar
  87. Stushnoff C (1985) Cryopreservation of in vitro shoots from Prunus pennsylvanica and Prunus fruticosa. FAO/IBPGR Plant Genet Resour Newslett 51:48Google Scholar
  88. Stushnoff C, Seufferheld M (1995) Cryopreservation of apple (Malus species) genetic resources. In: Bajaj YPS (ed) Biotechnology in agriculture and forestry. Springer-Verlag, Berlin, pp 87–101Google Scholar
  89. Suzuki M, Niino T, Akihama T, Oka S (1997) Shoot formation and plant regeneration of vegetative pear buds cryopreserved at −150 degree C. J Jpn Soc Hortic Sci 66:29–34CrossRefGoogle Scholar
  90. Taniguchi K, Tanaka R, Ashitani N, Miyagawa H (1988) Freeze preservation of tissue-cultured shoot primordia of the annual Haplopappus gracilis (2n=4). Jpn J Genet 63:267–272CrossRefGoogle Scholar
  91. Towill LE (1981) Solanum etuberosum: a model for studying the cryobiology of shoot-tips in the tuber-bearing Solanum species. Plant Sci Lett 20:315–324CrossRefGoogle Scholar
  92. Towill LE (1984) Survival at ultra-low temperatures of shoot tips from Solanum tuberosum groups Andigena, Phureja, Stenotomum, Tuberosum, and other tuber-bearing Solanum species. CryoLetters 5:319–326Google Scholar
  93. Towill LE (1988) Survival of shoot tips from mint species after short-term exposure to cryogenic conditions. Hortscience 23:839–841Google Scholar
  94. Towill LE, Bonnart R (2005) Cryopreservation of apple using nondesiccated sections from winter-collected scions. CryoLetters 26:323–332PubMedGoogle Scholar
  95. Towill LE, Forsline PL (1999) Cryopreservation of sour cherry (Prunus cerasus L.) using a dormant bud vegetative bud method. CryoLetters 20:215–222Google Scholar
  96. Towill LE, Forsline PL, Walters C, Waddell JW, Laufman J (2004) Cryopreservation of Malus germplasm using winter vegetative bud method: results from 1915 accessions. CryoLetters 25:323–334Google Scholar
  97. Towill LE, Widrlechner M (2004) Cryopreservation of Salix species using sections from winter vegetative scions. CryoLetters 25:71–80Google Scholar
  98. Turner SR, Senaratna T, Bunn E, Tan B, Dixon KW, Touchell DH (2001) Cryopreservation of shoot tips from six endangered Australian species using modified vitrification protocol. Ann Bot 87:371–378CrossRefGoogle Scholar
  99. Tyler N, Stushnoff C (1988) Dehydration of dormant apple buds at different stages of cold acclimation to induce cryopreservability in different cultivars. Can J Plant Sci 68:1169–1176CrossRefGoogle Scholar
  100. Uchendu EE, Leonard SW, Traber MG, Reed BM (2009) Vitamin C and E improve regrowth and reduce lipid peroxidation of blackberry shoot tips following cryopreservation. Plant Cell Rep 29:25–35CrossRefPubMedGoogle Scholar
  101. Uchendu EE, Muminova M, Gupta S, Reed BM (2010) Antioxidant and anti-stress compounds improve regrowth of cryopreserved in vitro grown Rubus shoot tips. In Vitro Cell Dev Biol Plant 46:386–393CrossRefGoogle Scholar
  102. Uemura M, Sakai A (1980) Survival of carnation (Dianthus caryophyllus L.) shoot apices frozen to the temperature of liquid nitrogen. Plant Cell Physiol 21:85–94Google Scholar
  103. Van den Houwe I, Swennen R (2000) Characterization and control of bacterial contaminants in in vitro cultivars of banana (Musa spp.) Acta Hortic 530:69–70CrossRefGoogle Scholar
  104. Volk GM, Bonnart R, Krueger R, Lee R (2012) Cryopreservation of citrus shoot tips using micrografting for recovery. CryoLetters 33:418–426PubMedGoogle Scholar
  105. Volk GM, Bonnart R, Waddell J, Widrlechner MP (2009) Cryopreservation of dormant buds from diverse Fraxinus species. CryoLetters 30:262–267PubMedGoogle Scholar
  106. Volk GM, Henk AD, Jenderek MM, Richards CM (2016) Probablistic viability calculations for cryoprocessing vegetatively propagated collections in genebanks. Gen Res Crop Evol 62:765–794CrossRefGoogle Scholar
  107. Volk GM, Waddell J, Bonnart R, Towill L, Ellis D, Laufman J (2008) High viability of dormant Malus buds after 10 years of storage in liquid nitrogen vapor. CryoLetters 29:89–94PubMedGoogle Scholar
  108. Westwood M (1989) Maintenance and storage: clonal germplasm. Plant Breed Rev 7:111–128Google Scholar
  109. Wilson AD (1996) Resources and testing of endophyte - infected germplasm in national grass repository collections. In: Redlin SC, Carris LM (eds) Endophytic fungi in grasses and woody plants. Systematics, Ecology and Evaluation, pp 179–195Google Scholar
  110. Withers LA (1985) Cryopreservation of cultured cells and meristems. In: Vasil IK (ed) Cell culture and somatic cell genetics of plants, vol Vol. 2. Academic Press, NY, pp 253–316Google Scholar

Copyright information

© The Society for In Vitro Biology 2017

Authors and Affiliations

  1. 1.USDA-ARS Plant and Animal Genetic Resources Preservation UnitFort CollinsUSA
  2. 2.USDA-ARS National Clonal Germplasm RepositoryCorvallisUSA

Personalised recommendations