COPPER AMINE OXIDASE1 (CuAO1) of Arabidopsis thaliana Contributes to Abscisic Acid-and Polyamine-Induced Nitric Oxide Biosynthesis and Abscisic Acid Signal Transduction

Abstract

Polyamines (PA), polyamine oxidases, copper amine oxidases, and nitric oxide (NO) play important roles in physiology and stress responses in plants. NO biosynthesis as a result of catabolism of PA by polyamine oxidases and copper amine oxidases may explain in part PA-mediated responses. Involvement of a copper amine oxidase gene, COPPER AMINE OXIDASE1 (CuAO1), of Arabidopsis was tested for its role in stress responses using the knockouts cuao1-1 and cuao1-2. PA-induced and ABA-induced NO production investigated by fluorometry and fluorescence microscopy showed that the cuao1-1 and cuao1-2 are impaired in NO production, suggesting a function of CuAO1 in PA and ABA-mediated NO production. Furthermore, we found a PA-dependent increase in protein S-nitrosylation. The addition of PA and ABA also resulted in H(2)O(2) increases. cuao1-1 and cuao1-2 showed less sensitivity to exogenous ABA supplementation during germination, seedling establishment, and root growth inhibition as compared to wild-type. In response to ABA treatment, expression levels of the stress-responsive genes RD29A and ADH1 were significantly lower in the knockouts. These observations characterize cuao1-1 and cuao1-2 as ABA-insensitive mutants. Taken together, our findings extend the ABA signal transduction network to include CuAO1 as one potential contributor to enhanced NO production by ABA.

Speculation: Polyamines are important in abiotic stress signaling

“…In contrast, exogenous polyamines, especially putrescine, induced NO generation in soybean [50]. Reduced NO release was observed in copper amino oxidase 1 knock-out Arabidopsis [51]. These results suggest that DAO might be involved in Page 13 of 33 A c c e p t e d M a n u s c r i p t 13 NO biosynthesis induced by polyamines.…”

“…As Fe-superoxide-dismutase, dehydroascorbate reductase and monodehydroascorbate reductase are also polyamine-induced S-nitrosylation target proteins, NO-modulated S-nitrosylation is also a possible link between polyamines and stress responses [51]. The mode of action by which polyamines affect S-nitrosylation may differ for individual polyamines [55].…”

“…However, different polyamines have different effects on H+-ATPase, depending on their type, concentration, and tissue-specific expression [6]. These changes are related not only to their stimulatory effect on the interaction between 14-3-3 protein with H+ -ATPase [51], but also for example to polyamine-activated Ca 2+ efflux [6].…”

Cross Talk between Nitric Oxide and Phytohormones Regulate Plant Development during Abiotic Stresses

“…Exposure to low temperature induces oxidative and nitrosative stress thereby promoting NO synthesis [119], which serves as a potential link between PA and ABA to induce stress responses in plants [120]. Literature indicated extensive cross talk among NO, ABA, PAs, and H 2 O 2 to modulate various physiological and stress responses under low temperature conditions [110,121].…”

The Role of Polyamines in Plant Disease Resistance

“…NO has emerged as a key mediator of plant defense responses, and it is known that Spm and Spd are potent NO inducers (Tun et al, 2006;Wimalasekera et al, 2011a). Although further studies are needed to determine the NO generation mechanism in disease resistance, it has been reported that a knockout mutant of CuAO1, one of the AO genes in Arabidopsis, showed an impaired PA-induced NO release (Wimalasekera et al, 2011b).…”