Cloning and characterization of Arabidopsis and Brassica juncea flavin-containing amine oxidases

Abstract

Polyamines (PAs) are low molecular weight metabolites involved in various physiological and developmental processes in eukaryotic and prokaryotic cells. The cellular PA level is regulated in part by the action of amine oxidases (AOs) including copper diamine oxidases (DAOs) and flavoprotein polyamine oxidases (PAOs). In this study, the isolation and characterization of flavin amine oxidases (FAOs) from Brassica juncea (BJFAO) and Arabidopsis (ATFAO1) are reported that were clustered in the same group as polyamine oxidases from maize (MPAO) and barley (BPAO1) and monoamine oxidases from mammalian species. ATFAO1 was temporally and spatially regulated in Arabidopsis and showed distinct expression patterns in response to different stress treatments. To investigate the in vivo function of FAO, transgenic Arabidopsis plants expressing sense, antisense, and double-stranded BJFAO RNAs were generated and those with altered activity of FAOs were selected for further characterization. It was found that the shoot regeneration response in transgenic plants was significantly affected by the modulated PA levels corresponding to FAO activities. Tissues that originated from transgenic plants with down-regulated FAO activity were highly regenerative, while those from transgenic plants with upregulated FAO activity were poorly regenerative. The shoot regeneration capacity in these transgenic plants was related to the levels of individual PAs, suggesting that FAO affects shoot regeneration by regulating cellular PAs. Furthermore, it was found that the effect of FAO activity on shoot regeneration was exerted downstream of the Enhancer of Shoot Regeneration (ESR1) gene, which may function in a branch of the cytokinin signalling pathway.

The role of vacuolar processing enzyme (VPE) from Nicotiana benthamiana in the elicitor-triggered hypersensitive response and stomatal closure

“…In NbVPE1a/1b -silenced plants, the up-regulation of NbrbohB is not consistent with the observed increase in AOS fluorescence in guard cells in response to elicitors, suggesting that NbrbohB may not be the key contributor to additional AOS accumulation in guard cells triggered by elicitors. Other enzymes (such as cell wall peroxidases, amine oxidase, oxalate oxidase, and flavin-containing oxidase) may account for AOS production (Cona et al , 2006 a , b ; Lim et al , 2006; Tisi et al , 2008; Gabaldón, 2010; Tamás et al , 2010). …”

Polyamine catabolism is involved in response to salt stress in soybean hypocotyls

“…On the other hand, CuAO and PAO activities modulate plant PA levels generating H 2 O 2 among other products (Lim et al, 2006;Marina et al, 2008;Rodríguez et al, 2009). Since H 2 O 2 functions as a signal molecule activating many of the plant responses deployed to cope with stress, it is believe that its generation from PA oxidation (along with PA depletion) might orchestrate (at least partially) plant adaptation to these conditions (Moschou et al, 2008;Rodríguez et al, 2009).…”

Arabidopsis NATA1 acetylates putrescine and decreases defense-related hydrogen peroxide accumulation

“…Polyamine oxidase activity was assayed spectrophotometrically (Lim et al, 2006;Tavladoraki et al, 2006). Leaves (200 mg) were ground in liquid nitrogen, homogenized in 0.2 M sodium phosphate buffer, pH 6.5 (1:5 w/v), and centrifuged at 12,000g for 20 min.…”