Sites and Regulation of Polyamine Catabolism in the Tobacco Plant. Correlations with Cell Division/Expansion, Cell Cycle Progression, and Vascular Development

Abstract

We previously gave a picture of the homeostatic characteristics of polyamine (PA) biosynthesis and conjugation in tobacco (Nicotiana tabacum) plant organs during development. In this work, we present the sites and regulation of PA catabolism related to cell division/expansion, cell cycle progression, and vascular development in the tobacco plant. Diamine oxidase (DAO), PA oxidase (PAO), peroxidases (POXs), and putrescine N-methyltransferase expressions follow temporally and spatially discrete patterns in shoot apical cells, leaves (apical, peripheral, and central regions), acropetal and basipetal petiole regions, internodes, and young and old roots in developing plants. DAO and PAO produce hydrogen peroxide, a plant signal molecule and substrate for POXs. Gene expression and immunohistochemistry analyses reveal that amine oxidases in developing tobacco tissues precede and overlap with nascent nuclear DNA and also with POXs and lignification. In mature and old tissues, flow cytometry indicates that amine oxidase and POX activities, as well as pao gene and PAO protein levels, coincide with G2 nuclear phase and endoreduplication. In young versus the older roots, amine oxidases and POX expression decrease with parallel inhibition of G2 advance and endoreduplication, whereas putrescine N-methyltransferase dramatically increases. In both hypergeous and hypogeous tissues, DAO and PAO expression occurs in cells destined to undergo lignification, suggesting a different in situ localization. DNA synthesis early in development and the advance in cell cycle/endocycle are temporally and spatially related to PA catabolism and vascular development.Polyamines (PAs) are abundant DNA-and RNAbinding organic cations. They have been correlated with specific roles in embryonic development (Kusunoki and Yasumasu, 1978), carcinogenesis and immune system functions (Seiler et al., 1998), defense (Schroder et al., 1998), antibiotic potency (Petropoulos et al., 2004), cell proliferation and apoptosis (for review, see Wallace et al., 2003;Janne et al., 2004), and in many biotic and abiotic stresses (Jokela et al., 1997;Kurepa et al., 1998;Perez-Amador et al., 2002; for review, see Bouchereau et al., 1999). Investigations on PA physiological functions have been focused mainly on changes in their levels and spectra, leaving the biological significance to be determined. Although genetic analyses have been conducted at the gene level (Laurenzi et al., 1999;Sebela et al., 2001;Rea et al., 2002;Papadakis and Roubelakis-Angelakis, 2005). H 2 O 2 produced by the action of diamine oxidases (DAOs) and PA oxidases (PAOs) can be utilized by POX enzymes in wallstiffening reactions during cell growth and differentiation (Wisniewski et al., 2000). In alkaloid producing plants, such as tobacco (Nicotiana tabacum), putrescine (Put), apart from serving as substrate for spermidine (Spd) biosynthesis or for oxidation (Bagni and Tassoni, 2001), is N-methylated by Put N-methyltransferase (PMT), which catalyzes the first committed steps in the biosynthesis of n...

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

“…Another possible explanation for the lack of phenotype shown by A-ZmPAO plants could be the involvement of additional and/or alternative H 2 O 2 sources, such as apoplastic CuAOs, that could cooperate with PAOs in H 2 O 2 delivery during tobacco xylem tissue differentiation. Indeed the simultaneous presence of CuAO and PAO activity working at the same time in the same tissues has been previously reported in tobacco, where the two enzymes have been proposed to cooperate during physiological and stress response events, such as lignification of vascular tissues (Paschalidis and Roubelakis-Angelakis, 2005) and wound healing responses . Furthermore, the phenotype shown by the RNAi-SAMDC transgenic plants could be ascribable to the absence of some specific PA directly involved in xylem differentiation, and therefore unrelated to its catabolism to H 2 O 2 and/or to the PA/H 2 O 2 ratio, once more underlining the complexity of PA physiology.…”

“…In xylem precursors, PAO mainly has a cytoplasmic localization and it was shown that as the cells mature, the enzyme will accumulate in the cell wall parallel to secondary wall deposition and developmental cell death (Cona et al, 2005). Development of vascular tissues is associated with cell cycle/endocycle progression and amine oxidase expression in tobacco (Paschalidis and Roubelakis-Angelakis, 2005). It has been proposed that these events are to be linked with the physiological need for the higher production of H 2 O 2 via amine oxidases in the secretion pathway (Cona et al, 2005) and in the apoplast to drive peroxidase-catalyzed cross linking of cell wall polysaccharides and proteins to complete cell wall maturation, to stimulate endoreduplication, and possibly to act as a signal triggering xylem precursor cell death (Cona et al, 2005;Paschalidis and Roubelakis-Angelakis, 2005).…”

“…Development of vascular tissues is associated with cell cycle/endocycle progression and amine oxidase expression in tobacco (Paschalidis and Roubelakis-Angelakis, 2005). It has been proposed that these events are to be linked with the physiological need for the higher production of H 2 O 2 via amine oxidases in the secretion pathway (Cona et al, 2005) and in the apoplast to drive peroxidase-catalyzed cross linking of cell wall polysaccharides and proteins to complete cell wall maturation, to stimulate endoreduplication, and possibly to act as a signal triggering xylem precursor cell death (Cona et al, 2005;Paschalidis and Roubelakis-Angelakis, 2005). Accordingly, Spd treatment at a concentration similar to that found in maize roots (Cohen, 1998) suppressed root growth by inhibiting cell elongation and altering cell cycle phase distributions in maize primary root apices, thus allowing cells to initiate their differentiation programs (Table I; Fig.…”

“…The abundant expression of plant CuAOs and ZmPAO in tissues undergoing lignification or extensive cell wall-stiffening events, such as vascular tissues, epidermis, and wound periderm, suggests that these enzymes influence plant growth and development as well as taking part in defense responses by affecting cell wall strengthening and rigidity, through H 2 O 2 production (Cona et al, 2005(Cona et al, , 2006Paschalidis and Roubelakis-Angelakis, 2005;Angelini et al, 2008). 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).…”

Spermidine affects the transcriptome responses to high temperature stress in ripening tomato fruit

“…Exogenous Put improved Indian mustard seedling growth by preventing lipid peroxidation and denaturation of macromolecules through the induction of antioxidative enzymes and the increase of glutathione and carotenoid under NaCl stress (Verma and Mishra, 2005). Conversely, polyamines may act as a mediator or secondary messenger to activate a vast genetic network with a potential to provide defense against biotic and abiotic stresses (Paschalidis and Roubelakis-Angelakis, 2005;Cona et al, 2006). It has been proved that a wide array of genes regulating transcription, translation, signal transduction, stress protein biosynthesis, ethylene biosynthesis and action, isoprenoid and flavonoid biosyntheses was activated by polyamines.…”