Sandhya Gupta* and Barbara M. Reed
U.S. Department of Agriculture, Agricultural Research Service, National Clonal Germplasm Repository, 33447 Peoria Road, Corvallis, Oregon 97333, USA
*Corresponding author, Present address: Tissue Culture and Cryopreservation Unit, National Bureau of Plant Genetic Resources, Pusa Campus, New Delhi 110012, India. Email: firstname.lastname@example.org.
Encapsulation-dehydration and PVS2-vitrification cryopreservation protocols were evaluated for the long-term conservation of a diverse group of Rubus germplasm. Cold acclimation for a 4-week period prior to cryopreservation was necessary for regrowth of shoot apices from blackberry and raspberry genotypes. For the encapsulation-dehydration protocol, encapsulated apices were pretreated in 0.75 M sucrose for 20 h, desiccated 6-h under laminar flow to ~20% moisture content, then plunged in liquid nitrogen (LN) and rapidly warmed. The PVS2-vitrification protocol included pretreating shoot tips on 5% dimethyl sulfoxide (DMSO) medium for 48 h, exposure to loading solution (LS) and PVS2 for 20 min each at 25ºC, followed by immersion in LN and rapid warming. Shoot tips of 25 genotypes in 9 Rubus species and 9 Rubus hybrids were successfully cryopreserved with recovery of 60-100% using the encapsulation-dehydration protocol. Four genotypes of 3 species were tested using the vitrification protocol with 71% average regrowth. The present results indicate that both of these improved cryopreservation protocols can be applied to a diverse range of Rubus genetic resources.
Keywords: cold acclimation, germplasm, liquid nitrogen, Rubus
Source: CryoLetters 27 (1), 29-42 (2006).