Articles
PRELIMINARY RESULTS ON DESICCATION AND PVS2-VITRIFICATION OF ‘CARRIZO’ CITRANGE SYNTHETIC SEEDS AS PRE-TREATMENTS TO CRYOPRESERVATION
Article number
892_38
Pages
311 – 318
Language
English
Abstract
Advanced cryopreservation techniques can provide cheap and safe back-ups to traditional ex situ conservation approaches of fruit germplasm, including Citrus species.
At the ultra-low temperature of liquid nitrogen (-196°C), plant cells, tissues and organs can be safely stored for theoretically unlimited time.
Among the innovative cryoprocedures, storage of synthetic seeds (i.e., encapsulated in vitro-derived propagules) in liquid nitrogen has repeatedly proven to be one of the most effective.
The technique is a multi-step process, including (i) pre-culturing of the encapsulated explants (generally shoot tips or nodal segments) in sucrose-containing medium, (ii) removal of the freezable water from the cells by desiccation over silica gel or by treatment with highly-concentrated cryoprotectant solutions (such as PVS2), (iii) direct immersion of synthetic seeds in liquid nitrogen, (iv) thawing and (v) conversion of synthetic seeds into plantlets.
As a preliminary step towards the optimization of a cryopreservation protocol for Carrizo citrange [Citrus sinensis (L.) Osbeck x Poncirus trifoliate L. Raf.] synthetic seeds, this study investigated the effect on moisture content and regrowth rate of different pre-freezing treatments, i.e., (i) the exposure to increasing sucrose concentrations (0.1, 0.3 and 0.7 M, each one for 24 h), (ii) the desiccation (from one to 7 h), and (iii) the treatment with PVS2 (90 or 180 min, at 0°C). Best result was achieved when sucrose preculture was followed by a 5-hour exposure to silica gel; this treatment induced a consistent reduction of synthetic seed moisture content (MC) (from the initial 82 up to 23%), while the regrowth rate was affected to more limited extent (from 62 to 48%).
At the ultra-low temperature of liquid nitrogen (-196°C), plant cells, tissues and organs can be safely stored for theoretically unlimited time.
Among the innovative cryoprocedures, storage of synthetic seeds (i.e., encapsulated in vitro-derived propagules) in liquid nitrogen has repeatedly proven to be one of the most effective.
The technique is a multi-step process, including (i) pre-culturing of the encapsulated explants (generally shoot tips or nodal segments) in sucrose-containing medium, (ii) removal of the freezable water from the cells by desiccation over silica gel or by treatment with highly-concentrated cryoprotectant solutions (such as PVS2), (iii) direct immersion of synthetic seeds in liquid nitrogen, (iv) thawing and (v) conversion of synthetic seeds into plantlets.
As a preliminary step towards the optimization of a cryopreservation protocol for Carrizo citrange [Citrus sinensis (L.) Osbeck x Poncirus trifoliate L. Raf.] synthetic seeds, this study investigated the effect on moisture content and regrowth rate of different pre-freezing treatments, i.e., (i) the exposure to increasing sucrose concentrations (0.1, 0.3 and 0.7 M, each one for 24 h), (ii) the desiccation (from one to 7 h), and (iii) the treatment with PVS2 (90 or 180 min, at 0°C). Best result was achieved when sucrose preculture was followed by a 5-hour exposure to silica gel; this treatment induced a consistent reduction of synthetic seed moisture content (MC) (from the initial 82 up to 23%), while the regrowth rate was affected to more limited extent (from 62 to 48%).
Authors
M.A. Germanà, M. Lambardi, E.A. Ozudogru
Keywords
cryopreservation, desiccation, encapsulation, citrus rootstock, PVS2, vitrification
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