Activation of ADP-Glucose Pyrophosphorylase Gene Promoters by a WRKY Transcription Factor, AtWRKY20, in Arabidopsis thaliana L. and Sweet Potato (Ipomoea batatas Lam.)
Activation of ADP-Glucose Pyrophosphorylase Gene Promoters by a WRKY Transcription Factor, AtWRKY20, in Arabidopsis thaliana L. and Sweet Potato (Ipomoea batatas Lam.)
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DOI：
10.1626/pps.15.10
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发表时间：
2012-01-01
影响因子：
2.5
通讯作者：
Ueno, Osamu
中科院分区：
文献类型：
--
作者：
Nagata, Takafumi;Hara, Hiromichi;Ueno, Osamu
adp -葡萄糖焦磷酸化酶（AGPase）催化植物淀粉生物合成的第一个限制步骤。然而，AGPase基因的直接转录激活因子尚未确定。我们从拟南芥中分离到了一个WRKY转录因子cDNA， AtWRKY20，并纯化了相应的蛋白。用粒子轰击法瞬时表达AtWRKY20，可增强糖诱导的泰国红花AGPase大亚基基因ApL3启动子在泰国红花叶片中的表达。AtWRKY20在体外与ApL3启动子结合。AtWRKY20的表达受到蔗糖的强烈诱导，marmitol的诱导程度较低，ApL3基因的表达模式与AtWRKY20基因相似。瞬时表达实验表明，AtWRKY20还激活了小甘薯品种小甘薯AGPase小亚基基因ibAGP1的启动子。5'端缺失分析显示，在Koganesengan ibAGP1启动子中存在-1371 ~ -641负调控区和-640 ~ -180正调控区。AtWRKY20直接与Koganesengan ibAGP1启动子-623和-490位置之间的区域相互作用。这些结果表明，AIWRKY20直接作为ApL3启动子的转录激活因子，调控蔗糖或渗透剂诱导的拟蓝Ap13的表达。AtWRKY20可以直接增强Koganesengan ibAGP1启动子在甘薯中的表达。
ADP-glucose pyrophosphorylase (AGPase) catalyzes the first limiting step in starch biosynthesis in plants. However, the direct transcriptional activator of the AGPase genes has not yet been determined. We have isolated a WRKY transcription factor cDNA, AtWRKY20, from Arabidopsis thaliana and purified the corresponding protein. Transient expression of AtWRKY20 by particle bombardment enhanced expression of the promoter of ApL3, encoding a sugar-inducible AGPase large subunit gene of A. thahana, in leaves of A. thahana. AtWRKY20 bound to the ApL3 promoter in vitro. The expression of AtWRKY20 was strongly induced by sucrose or, to a lesser extent, by marmitol, and the expression pattern of the ApL3 gene mimicked that of the AtWRKY20 gene. Transient expression experiments demonstrated that AtWRKY20 also activated the promoter of Koganesengan ibAGP1 encoding an AGPase small subunit gene of sweet potato var. Koganesengan. A 5'-end deletion analysis revealed a negative regulatory region from -1371 to -641 and a positive regulatory region from -640 to -180 in the Koganesengan ibAGP1 promoter. AtWRKY20 interacted directly with the region between positions -623 and -490 in the Koganesengan ibAGP1 promoter. These results suggest that AIWRKY20 functions directly as a transcriptional activator of the ApL3 promoter and regulates the expression of Ap13 induced by sucrose or osmoticum in A. thaliana. Moreover, AtWRKY20 can enhance the expression of the Koganesengan ibAGP1 promoter directly in sweet potato.