Vegetatively-propagated germplasm is used to retain the exact genetic line (genotype) of a crop, such as a Red Delicious apple. Germplasm is distributed as cuttings or explants rather than seeds.  NPGS collections of vegetatively-propagated crops are maintained in field plantings which are vulnerable to insects, diseases and environmental challenges.  Frequent regeneration – for example garlic is replanted every year -- increases the vulnerability and cost of the collection.  One method to back-up vegetatively-propagated germplasm collections uses tissue culture, where plants are grown and maintained in a sterile environment containing nutrients, a carbon source and vitamins.   Cryopreservation of very small (1-2mm) meristematic shoot tips or dormant winter buds in liquid nitrogen (-196°C) presents an alternative method for long term storage that reduces the cost of maintaining growing plants.  Protocols for tissue culture and cryoprotection are crop and genotype dependent, with few protocols available for NPGS germplasm.  NCGRP has been developing and implementing cryopreservation methods for vegetatively- propagated crops for almost two decades. 

See protocols for cryopreservation methods used for shoot tips and dormant buds at NCGRP

Number and genera of vegetatively-propagated plants in long-term cryopreservation at NCGRP (as of September 27, 2010).

Taxon	MS	BD	1In progress	2Canadian GRP	Total # of accs.
Allium sativum	51		21		72
Corylus	4				4
Cydonia	1				1
Cynodon	25				25
Fragaria	73				73
Humulus	35				35
Ipomoea	9675		5		68
Lolium	15				15
Malus		2,233	28	302	2,563
Mentha	44				44
Musa			2		2
Prunus		50	25		75
Pyrus	151		1		152
Ribes	64		2		66
Rubus	100				100
Salix		17	10		27
Solanum	63				63
Zoysia	5				5
Total # of accs.	657	2,300	92	302	3,351

¹Cryopreserved but viability testing in progress
²samples from the Canadian Genetic Resources Program
MS-meristematic shoot tips
BD- dormant winter buds