Articles
Cryopreservation of alginate-coated in vitro-grown apices of apple, pear and sweet cherry
Article number
1234_23
Pages
175 – 180
Language
English
Abstract
In vitro shoot tips of three temperate fruit crops (apple, pear and sweet cherry) encapsulated in sodium alginate were successfully cryopreserved using two different methods based on vitrification or two-step freezing.
Initially, shoot tip cultures were cold-hardened for 4 weeks in 4°C. Explants (3 mm) aseptically dissected from cold hardened in vitro cultures were cold-treated in MS medium supplemented with 2.0 M sucrose and 100 mg L-1 vitamin C for 48 h at 4°C. After encapsulation in alginate gel, embedded shoot tips were dehydrated by exposure to a sterile air flow for a period of 8 h.
Three cooling procedures were used: rapid cooling by direct immersion of cryotube with embedded shoot tips in liquid nitrogen (vitrification); and two variants of two-step freezing by progressive cooling (0.5 to 10.0°C min-1) before immersion in liquid nitrogen.
Thawing was performed by placing the cryovials in a 40°C water bath for approximately 1 min.
Survival was defined as the percentage of the total number of shoot tips that showed a green colour after post culture according to an evaluation scale.
Average survival rate amounted to 91.3% in the case of two-step freezing by progressive cooling.
Encapsulated shoot tips immersed directly into liquid nitrogen (vitrification) were also cryopreserved successfully (on average 71.9% survival). The encapsulation dehydration method using alginate beads appears promising for the cryopreservation of rosaceous fruit species.
Initially, shoot tip cultures were cold-hardened for 4 weeks in 4°C. Explants (3 mm) aseptically dissected from cold hardened in vitro cultures were cold-treated in MS medium supplemented with 2.0 M sucrose and 100 mg L-1 vitamin C for 48 h at 4°C. After encapsulation in alginate gel, embedded shoot tips were dehydrated by exposure to a sterile air flow for a period of 8 h.
Three cooling procedures were used: rapid cooling by direct immersion of cryotube with embedded shoot tips in liquid nitrogen (vitrification); and two variants of two-step freezing by progressive cooling (0.5 to 10.0°C min-1) before immersion in liquid nitrogen.
Thawing was performed by placing the cryovials in a 40°C water bath for approximately 1 min.
Survival was defined as the percentage of the total number of shoot tips that showed a green colour after post culture according to an evaluation scale.
Average survival rate amounted to 91.3% in the case of two-step freezing by progressive cooling.
Encapsulated shoot tips immersed directly into liquid nitrogen (vitrification) were also cryopreserved successfully (on average 71.9% survival). The encapsulation dehydration method using alginate beads appears promising for the cryopreservation of rosaceous fruit species.
Authors
P. Zidova, F. Paprstein, J. Sedlak
Keywords
freezing, cooling, survival, evaluation, encapsulation, fruit, cultivar
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