Applications of differential scanning calorimetry in developing cryopreservation strategies for Parkia speciosa, a tropical tree producing recalcitrant seeds.
Shoot-tips of Parkia speciosa, a recalcitrant seed producing tropical leguminous tree withstood cryopreservation using encapsulation-vitrification in combination with trehalose preculture. Differential scanning calorimetry (DSC) revealed that trehalose moderated the thermal characteristics of the shoot-tips. A 30 min PVS2 treatment had the lowest glass transition temperature (Tg) (-50.2 +/- 1.1 degree C) when applied in combination with 5% (w/v) trehalose. The Tg increased to -40.2 +/- 1.0 degree C as the sugar concentration was decreased to 2.5 percent (w/v). Tg heat capacity for shoot-tips treated with 2.5 percent and 5 percent (w/v) trehalose and exposed to PVS2 for 30 min increased from 0.17 +/ 0.05 to 0.23 +/- 0.01 J per gram, respectively. Enthalpies of the melt-endotherm varied in proportion to trehalose concentration, for the 30 min PVS2 treatment, whereas the melt enthalpy for control shoots was greater than 150 J per gram and decreased to ca. 60 J per gram with 2.5 percent (w/v) trehalose. For 5 percent and 10 percent (w/v) trehalose treatments, enthalpy declined to ca. 24 and 12 J per gram respectively and freezing points were depressed to -75 degree C and -85 degree C with 2.5 percent and 5 percent trehalose (w/v), respectively. DSC elucidated the critical points at which vitrification occurred in germplasm exposed to trehalose and PVS2. A 60 min PVS2 treatment supporting ca. 70 percent survival was found optimal for stable glass formation during cooling and on rewarming.
Nadarajan
Jayanthi
J
University of Abertay Dundee, Bell Street, Dundee, Scotland, UK. j.nadarajan@kew.org
Mansor
Marzalina
M
Krishnapillay
Baskaran
B
Staines
Harry J
HJ
Benson
Erica E
EE
Harding
Keith
K
D002152:Calorimetry, Differential Scanning / Q000379:methods*; D015925:Cryopreservation / Q000379:methods*; D003451:Cryoprotective Agents; D031298:Mimosa / Q000502:physiology*; D018520:Plant Shoots / Q000254:growth & development; D012044:Regression Analysis; D012639:Seeds / Q000254:growth & development*; D014199:Trehalose
D003451:Cryoprotective Agents; D014199:Trehalose