Regulation of Sucrose Transporter Genes in Rice Embryos during Seed Germination
Date Issued
2007
Date
2007
Author(s)
Chen, Jia-Yi
DOI
zh-TW
Abstract
Sugars degraded from endosperm starch are the major nutrient source for rice seed germination. Since glucose transported from endosperm to scutellum would be resynthesized to sucrose in scutellum and further transported to shoot and root for seedling growth, the efficiency of sucrose transport between different tissues could be an important factor to determine seedling establishment and growth. In order to clarify the mechanism of sucrose transport during rice seed germination, an effort was made to apply carboxyfluorescein diacetate (CFDA) into seeds for monitoring sugar transport from endosperm to embryo, shoot and root. In addition, the expressions of sucrose transporter family genes (OsSUTs) were analyzed by real-time RT-PCR during seed germination. To identify the sugar effect on OsSUT gene expressions and the signal transduction pathway involved in the sugar-mediated regulation, various sugar molecules and their analogs were supplied to isolated embryos cultures. The data presented in this thesis indicated that sugars can be transported from endosperm to embryo、stem and root mediated by plasmodemata before 4 leaf-old stage. The ratio of endosperm sugar transported to shoot and to root would be changed at different growth stages. During seed germination, the expression levels of OsSUT1、2 and 4 in embryos were higher than OsSUT3 and 5. OsSUT1 and 2 expressions could be enhanced by 100 mM glucose and sucrose, but their sensitivities in response to sugar were different. OsSUT4 expression was also up-regulated by glucose but not by sucrose. Even glucose was a common factor to control the expression of OsSUT1, 2 and 4, the sugar-mediated signal transduction pathways were different. The intermediate product of glycolysis was an essential signal for enhancing OsSUT1 expression. On the other hand, glucose-enhanced OsSUT2 and 4 expressions were controlled by hexokinase -independent pathway. In addition to sugar effect, GA and light effects on OsSUTs genes were also identified in this study. The results showed the expression of OsSUT4 could be enhanced by GA, and expressions of OsSUT1 and 2 could be stimulated by light.
Subjects
蔗糖轉運蛋白
sucrose transporter
Type
thesis
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