Arabidopsis knockout mutation of ADC2 gene reveals inducibility by osmotic stress

Abstract

We isolated an Arabidopsis thaliana mutant line carrying an insertion of the En-1 transposable element at the ADC2 locus. The insertion causes a knockout of the arginine decarboxylase 2 gene. We demonstrated that ADC2 is the gene responsible for induction of the polyamine biosynthetic pathway by osmotic stress. No induction of ADC activity by the osmolite sorbitol could be observed in the homozygous mutant, indicating a predominant role of ADC2 in stress response. ADC activity is reduced in the mutant by 44% under non-stressed conditions and the mutant shows no obvious phenotype. This is the first report of a genetically mapped mutation in the polyamine biosynthetic pathway in plants.z 1999 Federation of European Biochemical Societies.

Polyamines: potent modulators of plant responses to stress

“…The availability of mutant collections generated by transposon now facilitates the identification of knockouts in any gene of interest using PCR-based mutant screening techniques (Ferrando et al 2004). By using these techniques, A. thaliana mutant line carrying an insertion of En-1 transposable element at the ADC2 locus which should be regarded as a complete loss of function or knockout mutation was used (Soyka & Heyer 1999). The ADC2 induction by osmotic stress is impaired in loss of function and shows no phenotype change under normal growth condition.…”

BUD2, encoding an S-adenosylmethionine decarboxylase, is required for Arabidopsis growth and development

“…So far, two members of ADC, SPDS and SPMS genes [6,19,24,47], and four members of SAMDC genes have been identified in the Arabidopsis genome [29]. Previous studies indicated that ADC and SPDS members are functionally redundant, because a mutation in either gene member does not cause significant phenotypic changes [20,21,24,47]. Neverthe- less, the disruption of ACL5, one of SPMS genes, results in a severe dwarfism and an increased organ vascularization [11,22], indicating that two SPMS genes are not completely redundant during developmental process.…”

“…Although application of inhibitors is very useful in studying the polyamine biosynthetic pathway and in ex- [11,[19][20][21][22][23][24]. However, no mutant defective in SAMDC has been reported yet, although SAMDC cDNAs were cloned and their transgenic plants have been generated [25][26][27][28][29].…”

“…Putrescine is derived either from ornithine catalyzed by ornithine decarboxylase (ODC) or from arginine through several steps catalyzed by arginine decarboxylase (ADC), agmatine iminohydrolase and N-carbamoylputrescine amidohydrolase. Spermidine and spermine are synthesized from putrescine through spermidine and spermine synthases (SPDS and SPMS) from the donor of decarboxylated S-adenosylmethionine (dcSAM), which is produced from S-adenosylmethionine (SAM) by the action of S-adenosylmethionine decarboxylase (SAMDC).Although application of inhibitors is very useful in studying the polyamine biosynthetic pathway and in ex- [11,[19][20][21][22][23][24]. However, no mutant defective in SAMDC has been reported yet, although SAMDC cDNAs were cloned and their transgenic plants have been generated [25][26][27][28][29].…”

Induction of the Arginine Decarboxylase ADC2 Gene Provides Evidence for the Involvement of Polyamines in the Wound Response in Arabidopsis

“…In addition, two ADC genes have been described in several plant species such as Arabidopsis (ADC1 or ARGdc, At2g16500 and ADC2 or SPE2, At4g34710; Watson and Malmberg, 1996;Watson et al, 1997;Galloway et al, 1998). ADC1 has been found to be expressed in all tissues tested, whereas ADC2 is mainly expressed in siliques and cauline leaves, and is induced upon osmotic stress (Soyka et al, 1999).…”