Urano Kaoru, Yoshiba Yoshu, Nanjo Tokihiko, Ito Takuya, Yamaguchi-Shinozaki Kazuko, Shinozaki Kazuo
Laboratory of Plant Molecular Biology, RIKEN Tsukuba Institute, 3-1-1 Koyadai, Tsukuba, Ibaraki 305-0074, Japan.
Biochem Biophys Res Commun. 2004 Jan 9;313(2):369-75. doi: 10.1016/j.bbrc.2003.11.119.
Arginine decarboxylase (ADC) catalyzes the first step of polyamine (PA) biosynthesis to produce putrescine (Put) from arginine (Arg). One of the 2 Arabidopsis ADC genes, AtADC2, is induced in response to salt stress causing the accumulation of free Put. To analyze the roles of stress-inducible AtADC2 gene and endogenous Put in stress tolerance, we isolated a Ds insertion mutant of AtADC2 gene (adc2-1) and characterized its phenotypes under salt stress. In the adc2-1 mutant, free Put content was reduced to about 25% of that in the control plants and did not increase under salt stress. Furthermore, the adc2-1 mutant was more sensitive to salt stress than the control plants. The stress sensitivity of adc2-1 was recovered by the addition of exogenous Put. These results indicate that endogenous Put plays an important role in salt tolerance in Arabidopsis. AtADC2 is a key gene for the production of Put under not only salinity conditions, but also normal conditions.
精氨酸脱羧酶（ADC）催化多胺（PA）生物合成的第一步，从精氨酸（Arg）生成腐胺（Put）。拟南芥的两个ADC基因之一AtADC2，在盐胁迫响应中被诱导，导致游离Put积累。为了分析胁迫诱导的AtADC2基因和内源性Put在胁迫耐受性中的作用，我们分离了AtADC2基因的Ds插入突变体（adc2-1），并对其在盐胁迫下的表型进行了表征。在adc2-1突变体中，游离Put含量降至对照植物的约25%，并且在盐胁迫下没有增加。此外，adc2-1突变体比对照植物对盐胁迫更敏感。通过添加外源Put可恢复adc2-1的胁迫敏感性。这些结果表明，内源性Put在拟南芥的耐盐性中起重要作用。AtADC2不仅是盐度条件下，也是正常条件下Put产生的关键基因。
