Developmental expression and biochemical analysis of the Arabidopsis atao1 gene encoding an H₂O₂‐generating diamine oxidase

Abstract

SummaryA copper amine oxidase encoding gene, atao1, has been isolated and characterized from Arabidopsis thaliana. Sequence analysis reveals that atao1 encodes a 668 amino acid polypeptide (ATAO1) with 48% identity to copper amine oxidases from pea and lentil. The promoter region of atao1 was transcriptionally fused with the reporter genes encoding β-glucuronidase and modified green fluorescent protein. Analysis of transgenic Arabidopsis together with in situ hybridization of wild-type plants reveals temporally and spatially discrete patterns of gene expression in lateral root cap cells, vascular tissue of roots, developing leaves, the hypocotyl, and in the style/stigmatal tissue. Enzyme activity assays show that ATAO1 preferentially oxidizes the aliphatic diamine putrescine with production of the corresponding aldehyde, ammonia and hydrogen peroxide, a recognized plant signal molecule and substrate for peroxidases. Histochemical analysis reveals that atao1 expression in developing tracheary elements precedes and overlaps with lignification and therefore is a good marker for vascular development. In both vascular tissue and the root cap, atao1 expression occurs in cells destined to undergo programmed cell death.

Perturbation of Polyamine Catabolism Can Strongly Affect Root Development and Xylem Differentiation

“…Importantly, an additional role for CuAOs and PAOs in PCD associated with developmental differentiation, has been proposed (Møller and McPherson, 1998;Cona et al, 2005). Indeed, the presence of PAO (Cona et al, 2005; this work) and CuAO (Møller and McPherson, 1998) proteins in developing root tracheary elements and sloughed root cap cells of maize and Arabidopsis seedlings, respectively, suggests their potential involvement, as H 2 O 2 -delivering sources, in PCD of both cell types. Thus it is evident that both PA anabolism and catabolism through either cell autonomous and nonautonomous pathways may mediate physiological events associated with PA-induced regulation of growth and development as well as induction of PCD involved in tissue differentiation or defense responses.…”

Reactive Oxygen Species in Plant Cell Death

“…These lesions were attributed to changes in redox homeostasis rather than to H 2 O 2 , as evidenced by lower ascorbate levels in vtc mutants than in the wildtype plants (Pavet et al, 2005). Finally, the localized expression pattern of the copper amine oxidaseencoding gene ATAO1, which produces H 2 O 2 associated with PCD in lateral root cap cells and developing tracheary elements, also hints to H 2 O 2 as a trigger for certain developmental cell death processes (Møller and McPherson, 1998). In summary, various ROS species and cellular redox changes can trigger different signaling cascades leading to PCD.…”

ACAULIS5 controlsArabidopsisxylem specification through the prevention of premature cell death

“…PAs have been shown to be involved in a variety of processes, such as cell proliferation and defense against both abiotic and biotic stresses, but they are also associated with the normal development of plants (Kumar et al, 1997;Walden et al, 1997). It ACAULIS5 controls Arabidopsis xylem specification through the prevention of premature cell death has also been proposed that they participate in the control of vascular development based on their effect on cell division, interaction with other hormones and H 2 O 2 produced during PA catabolism that could potentially affect processes such as vascular cambial activity, cell differentiation and cell death (Bais and Ravishankar, 2002;Møller and McPherson, 1998;Sebela et al, 2001). Indirect support for this suggestion was provided by spermidine-and spermine-deficient transgenic plants, which exhibited a stunted phenotype (Kumar et al, 1996).…”