Spatial and Temporal Distribution of Polyamine Levels and Polyamine Anabolism in Different Organs/Tissues of the Tobacco Plant. Correlations with Age, Cell Division/Expansion, and Differentiation

Abstract

Polyamine (PA) titers and biosynthesis follow a basipetal decrease along the tobacco (Nicotiana tabacum) plant axis, and they also correlate negatively with cell size. On the contrary, the titers of arginine (Arg), ornithine (Orn), and arginase activity increase with age. The free (soluble)/total-PA ratios gradually increase basipetally, but the soluble conjugated decrease, with spermidine (Spd) mainly to determine these changes. The shoot apical meristems are the main site of Spd and spermine biosynthesis, and the hypogeous tissues synthesize mostly putrescine (Put). High and low Spd syntheses are correlated with cell division and expansion, respectively. Put biosynthetic pathways are differently regulated in hyper-and hypogeous tobacco tissues: Only Arg decarboxylase is responsible for Put synthesis in old hypergeous vascular tissues, whereas, in hypogeous tissues, arginase-catalyzed Orn produces Put via Orn decarboxylase. Furthermore, Orn decarboxylase expression coincides with early cell divisions in marginal sectors of the lamina, and Spd synthase strongly correlates with later cell divisions in the vascular regions. This detailed spatial and temporal profile of the free, soluble-conjugated, and insoluble-conjugated fractions of Put, Spd, and spermine in nearly all tobacco plant organs and the profile of enzymes of PA biosynthesis at the transcript, protein, and specific activity levels, along with the endogenous concentrations of the precursor amino acids Arg and Orn, offer new insight for further understanding the physiological role(s) of PAs. The results are discussed in the light of age dependence, cell division/expansion, differentiation, phytohormone gradients, senescence, and sink-source relationships.Polyamines (PAs) are small polycations that represent important intrinsic developmental signals, linked to important developmental phenomena, including cell growth and division (Chattopadhyay et al., 2002;Theiss et al., 2002), morphogenesis (Paschalidis et al., 2001;Fos et al., 2003), stabilization of nucleic acids and membranes (Thomas and Thomas, 2001), protein synthesis and chromatin function (Mattheus, 1993), and biotic and abiotic stresses (Kurepa et al., 1998; PerezAmador et al., 2002;Navakoudis et al., 2003; for review, see Bouchereau et al., 1999). Eukaryotic cells synthesize putrescine (Put) directly from Orn through the activity of Orn decarboxylase (ODC). Plants and some bacteria also synthesize Put indirectly from Arg, by the activity of Arg decarboxylase (ADC). An aminopropyl group derived from decarboxylated S-adenosylmethionine (dSAM) is transferred to Put by spermidine synthase (SPDS) to form spermidine (Spd), and another aminopropyl group is added to Spd by spermine synthase (SPMS) to form spermine (Spm). The dSAM is formed by the activity of S-adenosyl-L-Met decarboxylase (SAMDC; for review, see Wallace et al., 2003).The positive charge of PAs enables them to interact electrostatically with polyanionic macromolecules within the cell. Spd and Spm can bridge the major and minor grooves ...

ABA-dependent amine oxidases-derived H2O2 affects stomata conductance

“…Previously, An et al 17 showed that DAO is involved in the ABA-induced stomata closure in Vicia faba. Paschalidis et al 18,19 showed that in Nicotiana tabacum plants PAO activity correlates with vascular tissues as observed here for Vitis vinifera. These results reinforce the view of direct involvement of PAOs-derived H 2 O 2 in stomata closure signaling cascade.…”

Abiotic Stress Generates ROS That Signal Expression of Anionic Glutamate Dehydrogenases to Form Glutamate for Proline Synthesis in Tobacco and Grapevine

“…In addition to Pro synthesis, the ammonia detoxification effect of GDH links the entrance of Glu into the Krebs-Henseleit (urea) cycle and to polyamine biosynthesis (Paschalidis et al, 2001). Under hyperammonia, Glu is shifted to synthesize Orn, which is recycled via arginase as part of the urea cycle (Paschalidis and Roubelakis-Angelakis, 2005a) and may be the substrate for Pro synthesis. Both Orn and Arg are used for the biosynthesis of polyamines Roubelakis-Angelakis, 2005a, 2005b), which may also play a role in the protection of plants against abiotic stress (Capell et al, 2004).…”

R2R3-NaMYB8 Regulates the Accumulation of Phenylpropanoid-Polyamine Conjugates, Which Are Essential for Local and Systemic Defense against Insect Herbivores inNicotiana attenuata

“…R, Root; SB, stem basal; SU, stem upper; SeL, senescent leaf; OL, old leaf; LL, locally W+OS-induced rosette leaf; SL, systemic rosette leaf; 1SL, first stem leaf; YL, young stem leaf; B, flower buds; EB, elongating flower buds; F, open flowers; GC, green capsules with seeds; RC, ripe capsules with seeds; FM, fresh mass; nd, not detected. putrescine and spermidine could be contributing to the differential spatiotemporal accumulation of CP and DCS in N. attenuata plants (Paschalidis and Roubelakis-Angelakis, 2005).…”