Cloning and characterization of PcRACK1 and PcPP2CA genes induced during warm stratification in dormant embryo axis of Prunus campanulata
Date Issued
2012
Date
2012
Author(s)
Chang, Yao-Wen
Abstract
Abstract
Stratification is defined as imbibed seeds under specific temperature. There’s two kinds of stratification: cold stratification and warm stratification. Cold stratification is widely used to break seed dormancy, while warm stratification combining with cold stratification is also used to break deep seed dormancy. From literatures it is known that cold stratification induces genes involved in bioactive gibberellins synthesis and promote germination. The mechanism to break dormancy by warm stratification, however, is not clear yet. Previous report indicated that seeds of Prunus campanulata after treatment of warm stratification would decrease ABA concentration.
Previous work in our lab found two gene fragments resembled AtRACK1B and AtPP2CA, which were known as negative regulators of ABA signaling in Arabidopsis thaliana. This study aims to obtain the full length of these two genes, named as PcRACK1 and PcPP2CA, and to express them in Arabidopsis thaliana to study their roles played in warm stratification of Prunus campanulata seeds.
Seeds of PcPP2CA overexpression (OE) line had higher germination rate on medium containing NaCl or ABA than wild type plant, while the germination rate of PcRACK1 OE line was lower than WT. The survival rate of PcRACK1 OE line and PcPP2CA OE line on medium supplemented with salt were both higher than wild type plant. In experiments qunitified the rate of water loss(RWL) of excised leaves, the result indicated that PcRACK1 OE line had slightly lower RWL than WT, while PcPP2CA OE line had higher RWL than that of WT. Infrared image obtained by infrared thermometry showed that no marked difference in canopy temperatures between PcRACK1 OE line and wild type plant, whereas canopy temperature of PcPP2CA OE line were significantly lower than wild type. PcRACK1 OE line had slightly higher drought tolerance than wild type in the drought stress experiment, while PcPP2CA OE line had much lower drought tolerance. We suggest that PcPP2CA might be a negative regulator involved in ABA signaling transduction pathway. We inferred that the underlying mechanism of warm stratification of cherry seeds is to reduce the seed sensitivity to ABA.
Subjects
Prunus campanulata Maxim.
ABA
warm stratification
Type
thesis
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