In Vitro Conservation and Cryopreservation of Buxus sempervirens L., a Critically Endangered Ornamental Shrub
2021
Negahdar, N. | Hashemabadi, D. | Kaviani, B.
Buxus sempervirens L. is an endangered ornamental shrub in the Hyrcanian forests in the northern part of Iran. B. sempervirens has excellent ornamental value. This species is at risk of extinction because of the boxwood blight disease. Hence, an urgent need to conserve it arises. This study aimed to evaluate the efficiency of in vitro storage techniques (cold preservation, and cryopreservation by encapsulation-dehydration and encapsulation-vitrification) as the methods of medium- and long-term conservation. The excised shoot tips were used as explants. Explants were encapsulated in alginate beads. This study was done in three sections, namely, cold preservation with pretreatments of encapsulation and dehydration with 0.75 M sucrose and air-desiccation followed by storage at 4°C; cryopreservation with pretreatments of encapsulation and dehydration with 0.75 M sucrose and air-desiccation followed by direct immersion in liquid nitrogen (LN); and cryopreservation with pretreatments of encapsulation, loading solution (LS) and vitrification with plant vitrification solution 3 (PVS3) followed by direct immersion in LN. After 6 months' cold storage, maximum survival (71.30%) was observed for encapsulated explants dehydrated by 0.75 M sucrose and air-desiccation. After cryopreservation, maximum survival was obtained for encapsulated explants dehydrated by 0.75 M sucrose and air-desiccation (66.30%) and encapsulation-vitrification (60.00%) for 30 min. Minimum survival of shoot tips in all experiments was obtained for non-pretreated (control) explants. The optimized in vitro conservation techniques can be utilized for germplasm preservation, breeding programs, and exchange of Buxus genetic resources.
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