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Science
> Biotechnology
> Decreasing Sensitivity of White Spruce Somatic Embryos to Desiccation and Imbibitional
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S.E. Pond and P. von Aderkas
Atlantic Forestry Centre
Centre of Forest Biologiy, University of Victoria
Introduction
White spruce somatic embryos can be desiccated to low water content
for use as synthetic seed or for direct germination. However, these
embryos lack a megagametophyte and seed coat to regulate water uptake,
and therefore require special methods to minimize imbibitional damage.
Several factors can affect the amount of damage suffered by embryos
during imbition, including cold pre-treatment of the embryos and method
and temperature of rehydration. The purpose of this study was to investigate
the effects of these factors on imbibitional damage in white spruce
somatic embryos by assessing the quality of the germinated embryos.
Slowly dried and flash-dried embryos were used to determine if the
method of desiccation affects imbibitional response.
Conclusions
Cold treatments increase the ability of embryos to survive severe
desiccation. Embryos that have been cold treated for a minimum of
four weeks are able to survive flash desiccation undamaged. The method
of drying affects rehydration response. Flash dried embryos suffer
less damage if directly rehydrated. Slowly dried embryos suffer less
damage if indirectly rehydrated. Cold treatments decrease the necessity
for slowly desiccated embryos to be indirectly rehydrated. These findings
have important implications for the development of synthetic seed.
It is possible that cold-treated, flash-dried embryos can be directly
planted without a protective coat to regulate water uptake. However,
slowly dried embryos will require pre-hydration in a saturated atmosphere
or encapsulation to regulate water uptake unless they have been cold-treated
at a temperature of 5o.
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