Overexpression of ADC2 in Arabidopsis induces dwarfism and late-flowering through GA deficiency
Overexpression of ADC2 in Arabidopsis induces dwarfism and late-flowering through GA deficiency
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DOI：
10.1111/j.1365-313x.2005.02465.x
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发表时间：
2005-08-01
期刊：
影响因子：
7.2
通讯作者：
Altabella, T
中科院分区：
文献类型：
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作者：
Alcázar, R;García-Martínez, JL;Altabella, T
我们获得了组成型过量表达精氨酸脱羧酶（ADC）基因之一ADC 2的拟南芥转基因植株。这些植物含有非常高水平的腐胺（Put），但没有观察到亚精胺和精胺含量的变化。从游离和共轭多胺的定量得到的结果表明，共轭可能是一个限制性的步骤，用于控制把植物生存在无毒范围内的稳态。具有增加的ADC 2转录物水平和升高的Put含量的转基因植物表现出矮化和延迟开花，并且通过施用赤霉素A（3）（GA（3））挽救了该表型。在ADC 2过表达植物中，生物活性GA（4）和GA（1）以及GA（9）（GA（4）的前体）的含量，以及AtGA 20 ox 1、AtGA 3 ox 1和AtGA 3 ox 3转录物的水平（通过实时PCR定量）低于野生型。通过微阵列分析检测到GA生物合成途径中编码早期酶的基因的表达没有变化。这些结果表明，Put积累影响GA代谢通过抑制生物合成步骤催化的GA 20-氧化酶和GA 3-氧化酶。
We have obtained Arabidopsis thaliana transgenic plants constitutively overexpressing ADC2, one of the two genes encoding arginine decarboxylase (ADC) in Arabidopsis. These plants contained very high levels of putrescine (Put) but no changes were observed in spermidine and spermine contents. The results obtained from quantification of free and conjugated polyamines suggest that conjugation may be a limiting step for control of Put homeostasis within a non-toxic range for plant survival. Transgenic plants with increased levels of ADC2 transcript and elevated Put content showed dwarfism and late-flowering, and the phenotype was rescued by gibberellin A(3) (GA(3)) application. The contents of bioactive GA(4) and GA(1), and of GA(9) (a precursor of GA(4)), as well as the levels of AtGA20ox1, AtGA3ox1 and AtGA3ox3 transcripts (quantified by real-time PCR) were lower in the ADC2 overexpressor plants than in the wild type. No change in the expression of genes encoding earlier enzymes in the GA biosynthesis pathway was detected by microarray analysis. These results suggest that Put accumulation affects GA metabolism through the repression of biosynthetic steps catalyzed by GA 20-oxidase and GA 3-oxidase.