An Arabidopsis Stress-Inducible Gene for Arginine Decarboxylase AtADC2, is Required for Accumulation of Putrescine in Drought and Salt Stress Response

Abstract

Arginine decarboxylase (ADC) catalyzes the first step of polyamine biosynthesis to produce putrescine (Put) from arginine. One of 2 Arabidopsis ADC genes, AtADC2 was induced in response to drought and salt stresses causing the accumulation of free Put. To analyze the roles of stress-inducible AtADC2 and endogenous Put in stress response, we characterized the adc2-1 mutant under drought and 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. This result suggests that AtADC2 is a key gene for the production of Put under not only stress conditions, but also normal conditions. Furthermore, the adc2-1 mutant was more sensitive to drought and salt stresses than the control plants. These results indicate that Put plays an important role in drought and salt stress response in Arabidopsis.