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標題: 不同前處理對番木瓜莖頂超低溫保存存活率之影響
Survival of cryopreserved shoot tips of papaya (Carica papaya L.) exposed to various pretreatments
作者: 朱麗淑
Ju, Lih-Shuwn
關鍵字: Papaya;番木瓜;Cryopreservation;cryoprotectant;超低溫保存;冷凍保護劑
出版社: 植物學系
本實驗以番木瓜台農二號(Carica papaya L. cv. Tainung No.2)組織
malondialdehyde )生成量變化情形及冷凍保護劑(cryoprotectant)對
膜及生理機能之傷害程度。番木瓜組織培養苗以abscisic acid (ABA)及
凍管(cryotube)中,經遞降溫系統以1℃/min降溫速率,降溫至 -40℃之
glycol)、DMSO(dimethyl sulfoxide)及glycerol等皆會隨濃度增加而
導致光合成率下降,而sorbitol、PEG( polyethylenglycol )、sucrose

Abstract This study used tissue cultured plantlets of papaya (
Carica papaya L. cv. Tainung No2. ) as materials for
investigation. The main purpose is to investigate the survival
ratio of the shoot tips under various pretreatments after
cryopreservation. To understand the degree of damage to the
overall physiology performance of papaya, MDA production of
shoot tips wasmeasured to indicate the effect of
cryopreservation on cell membrane, as well as the photosynthetic
rate of the leaves. Survival of cryopreserved shoot tips of
papaya did not increase when tissue cultured papayas was
pretreated with ABA ( 100mm abscisic acid ) and different low
temperatures treatment ( 20℃、15℃、10℃ ). After plantlets
were grown in hardening media supplemented with 0.5 M sucrose
for a week, the shoot tips were excised, dehydrated for 20 mins,
transferred to cryotubes and plunged directly into liquid
nitrogen for storage. After 24 hr, frozen shoot tips were thawed
at 40℃for 1 min and then transferred to regrowth media. The
survival of shoot tips was up to 60%. In another experiment,
tissue cultured plantlets were grown in standard hardening media
for a week, the shoot tips were excised, dehydrated for 40 mins,
treated with different cryoprotectants by shaking for 1 hr,
transferred to cryotubes and cooled at 1℃per minute to -40℃,
and then plunged into liquid nitrogen. After 24hr, frozen shoot
tips were thawed at 40℃for 1min and then transferred to
regrowth media. The survival of shoot tips was up to 77.8%. The
damage of membrane in shoot tips was measured as MDA production
from various procedures of cryopreservation. Application of
cryoprotectants increased the amounts of MDA synthesized,which
is higher than other treatments. These results suggest that
cryoprotectants have positive effect on lipid peroxidation of
cell membrane. Moreover, sucrose was the most effective one
among those cryoprotectants. As the results show, the
concentration of sucrose used in this experiment may be too high
for papaya shoot tips, therefore it caused osmotic stress,
resulting in lipid peroxidation of cell membrane. The effects
of various cryoprotectants on leaf photosynthetic rates were
also measured. Photosynthetic rates decreased with increasing
the concentrations of ethylene glycol, dimethyl sulfoxide and
glycerol. However, certain ranges of sorbitol,
polyethylenglycol, sucrose and proline caused increased
photosynthetic rates. Here we concluded that selecting of
suitable compositions and concentrations of cryoprotectants is a
major factor for cryopreserving papaya shoot tips.
Appears in Collections:生命科學系所

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