Effect of Exogenous Nitrate on Anaerobic Metabolism in Excised Rice Roots

Reggiani, Remo; Brambilla, I.; Bertani, Alcide

doi:10.1093/jxb/36.11.1698

Cited by 47 publications

(36 citation statements)

References 0 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…Ultimately, i.e. under prolonged O 2 stress, such up- regulation responses of N uptake must be compromised by restrictions in ATP supply (Reggiani et al, 1985).…”

Section: Resultsmentioning

confidence: 99%

Effects of Hypoxia on 13NH4+Fluxes in Rice Roots1

et al. 1998

View full text Add to dashboard Cite

Techniques of compartmental (efflux) and kinetic influx analyses with the radiotracer 13 NH 4 ؉ were used to examine the adaptation to hypoxia (15, 35, and 50% O 2 saturation) of root N uptake and metabolism in 3-week-old hydroponically grown rice (Oryza sativa L., cv IR72) seedlings. A time-dependence study of NH 4 ؉ influx into rice roots after onset of hypoxia (15% O 2 ) revealed an initial increase in the first 1 to 2.5 h after treatment imposition, followed by a decline to less than 50% of influx in control plants by 4 d. Efflux analyses conducted 0, 1, 3, and 5 d after the treatment confirmed this adaptation pattern of NH 4 ؉ uptake. Half-lives for NH 4 ؉ exchange with subcellular compartments, cytoplasmic NH 4 ؉ concentrations, and efflux (as percentage of influx) were unaffected by hypoxia. However, significant differences were observed in the relative amounts of N allocated to NH 4 ؉ assimilation and the vacuole versus translocation to the shoot. Kinetic experiments conducted at 100, 50, 35, and 15% O 2 saturation showed no significant change in the K m value for NH 4 ؉ uptake with varying O 2 supply. However, V max was 42% higher than controls at 50% O 2 saturation, unchanged at 35%, and 10% lower than controls at 15% O 2 . The significance of these flux adaptations is discussed.More than 70% of the worldЈs rice (Oryza sativa L.) is produced in intensively cultivated, irrigated lowland systems in Asia (International Rice Research Institute, 1997). In these systems N is generally the main factor limiting the realization of yield potentials (Kropf et al., 1993; Cassman et al., 1997). As a consequence, large amounts of mineral N fertilizers are used. According to one estimate, 7 ϫ 10 6 metric tons of N is applied each year to the 74 ϫ 10 6 ha of irrigated rice in Asia (Cassman and Pingali, 1995). However, unless the application of N fertilizer is timed precisely to match plant demand (Cassman et al., 1998), less than 50% of fertilizer N is usually recovered by the crop, because of high rates of loss through ammonia volatilization and denitrification (Craswell and Vlek, 1979; Vlek and Byrnes, 1986;Cassman et al., 1993). Clearly, the capacity of the root system to capture N in competition with these processes is critical. Mathematical modeling of the uptake process (Kirk and Solivas, 1997) shows that, under typical field conditions and following the initial flush of available N after fertilization, N absorption from the soil is rate limiting.In flooded lowland rice soils, where the bulk of the soil is hypoxic to anaerobic, the main form of plant-available N is NH 4 ϩ (Sasakawa and Yamamoto, 1978; Yu, 1985). This is in marked contrast to most (aerobic) agricultural soils, where NO 3 Ϫ is the predominant inorganic N species (Kronzucker et al., 1995b). There have been reports that NH 4 ϩ is the preferred N species taken up by rice (Bonner, 1946; Fried et al., 1965; Shen, 1969; Dijkshoorn and Ismunadji, 1972a, 1972b; Yoneyama and Kumazawa, 1974, 1975; Sasakawa and Yamamoto, 1978; Ancheng et al., ...

show abstract

“…Ultimately, i.e. under prolonged O 2 stress, such up- regulation responses of N uptake must be compromised by restrictions in ATP supply (Reggiani et al, 1985).…”

Section: Resultsmentioning

confidence: 99%

Effects of Hypoxia on 13NH4+Fluxes in Rice Roots1

et al. 1998

View full text Add to dashboard Cite

show abstract

“…The high level of reducing equivalents (NADH) within mitochondria prevailing in the anoxic tissue just before re-exposure to O, (Reggiani at al., 1985;Van Toai and Bolles, 1991) may well favor a rapid generation of active O, species, e.g. O,-, H,O,, and OH* during the first minutes of post-anoxia.…”

Section: Post-anoxic Aa Emissionmentioning

confidence: 99%

Dynamics of Acetaldehyde Production during Anoxia and Post-Anoxia in Red Bell Pepper Studied by Photoacoustic Techniques

et al. 1997

View full text Add to dashboard Cite

Acetaldehyde (AA), ethanol, and CO, production in red bell pepper (Capsicum annum 1.) fruit has been measured in a continu o u~ flow system as the fruit was switched between 20% O, and anaerobic conditions. Minimum gas phase concentrations of 0.5 nL L-l, 10 nL 1-', and 1 mL L-', respectively, can be detected employing a laser-based photoacoustic technique. This technique allows monitoring of low production rates and transient features in real time. At the start of anaerobic treatment respiration decreases by 60% within 0.5 h, whereas AA and ethanol production is delayed by 1 to 3 h. This suggests a direct slow-down of the tricarboxylic acid cycle and a delayed onset of alcoholic fermentation. Reexposure of the fruit to oxygen results in a 2-to 10-fold upsurge in AA production. A short anoxic period leads to a sharp transient peak lasting about 40 min, whereas after numerous and longer anoxic periods, post-anoxic AA production stays high for severa1 hours. High sensitivity of the fruit tissue to oxygen is further evidenced by a sharp decrease in post-anoxic AA production upon an early return to anaerobic conditions. Ethanol oxidatioo by the "peroxidatic" action of catalase is proposed to account for the immediate postanoxic AA upsurge.Fermentation occurs in fruits when oxygen flux to respiring cells is reduced below a critica1 value. Hypoxia occurs in bulky fruits under natural conditions during normal ripening due to impaired gas exchange with the atmosphere. The metabolic response and adaptation of plants to anaerobiosis has been extensively reviewed (Perata and Alpi, 1993; Pfister-Sieber and Braendle, 1994). Low oxygen concentrations are widely used in controlled atmosphere storage of harvested fruit, e.g. apples, with the goal of prolonging fruit shelf-life (Knee, 1991). Reduction of respiration rate and ethylene biosynthesis during controlled atmosphere storage does not, however, induce fermentation. Recently, storage in 1% O, was shown to extend the postharvest life of bell peppers (Lu0 and Mikitzel, 1996). Similarly, short-term anoxic treatments of harvested fruit improve fruit aroma and quality (Pesis, 1995). The physiological basis of the observed effects has yet to be clarified.

show abstract

“…Our results showed that root hypoxia led to some typical effects commonly observed in tomato 36,41 and in other plant redox state (NADH/NAD + ratio) and a higher adenylate energy charge, 24,25 through the consumption of the reducing power (NADH) generated by the glycolysis and by the NO 3 -reduction to nitrite (NO 2 -). In these tissues, NR activity often increases, either through increased gene expression, 26 or post-translational activation.…”

Section: Discussionmentioning

confidence: 60%

“…24 Both factors could contribute to root survival and suggest a possible role of NO 3 -reduction in oxygen deficiency tolerance. Moreover, in most plant tissues other than the rice coleoptile, NO 3 -reduction under and assayed spectrophotometrically in sample extracts using the phenol-hypochlorite method.…”

Section: Plant Development and Biomass Allocationmentioning

confidence: 99%

Prolonged root hypoxia effects on enzymes involved in nitrogen assimilation pathway in tomato plants

Horchani

Aschi‐Smiti²

2010

Plant Signaling & Behavior

View full text Add to dashboard Cite

IntroductionPlants grow in a dynamic environment, which frequently imposes constraints on growth and development. Among the adverse environmental factors commonly encountered by land plants, flooding is one of the most significant abiotic stresses. 1 Flooding of the soil can have a tremendous impact on the growth and survival of plants, and thereby on agricultural as well as natural ecosystems. In the last decades considerable progress has been made in our understanding of the mechanisms that enable certain plant species and cultivars to withstand periods with excess soil water or even complete submergence. Much of the research has been carried out with crop plant species, such as Oryza sativa, Zea mays, Trifolium subterraneum and Medicago sativa, 2-5 but wild species originating from wetland habitats have been also used, mostly for comparative studies. 6,7 With transient flooding or irrigation followed by slow drainage, or in natural wetlands, plant roots can become oxygen deficient because of slow transfer of dissolved oxygen in the waterfilled pore space of the soil. The decrease in ambient oxygen may not be, itself or alone, the perceived signal but could trigger metabolic responses, which then initiate the signalling cascade. 8 The immediate consequence of oxygen depletion is the reduction in respiration, thus diminishing ATP generation, and leading to a decrease in the ATP/ADP ratio and the adenylate energy charge. 9 In order to investigate the effects of root hypoxia (1-2% oxygen) on the nitrogen (N) metabolism of tomato plants (Solanum lycopersicum L. cv. Micro-Tom), a range of N compounds and N-assimilating enzymes were performed on roots and leaves of plants submitted to root hypoxia at the second leaf stage for three weeks. Obtained results showed that root hypoxia led to a significant decrease in dry weight (DW) production and nitrate content in roots and leaves. conversely, shoot to root DW ratio and nitrite content were significantly increased. contrary to that in leaves, glutamine synthetase activity was significantly enhanced in roots. The activities of nitrate and nitrite reductase were enhanced in roots as well as leaves. The higher increase in the Nh 4 + content and in the protease activities in roots and leaves of hypoxically treated plants coincide with a greater decrease in soluble protein contents. Taken together, these results suggest that root hypoxia leaded to higher protein degradation. The hypoxia-induced increase in the aminating glutamate dehydrogenase activity may be considered as an alternative N assimilation pathway involved in detoxifying the Nh 4 + , accumulated under hypoxic conditions. With respect to hypoxic stress, the distinct sensitivity of the enzymes involved in N assimilation is discussed. and 0.13 ± 0.03 g, respectively. The changes in the root and shoot dry weights (DW) and in shoot/root ratio were investigated after a three week period of hypoxic treatment. Root hypoxia decreased root and leaf DW production by 34 and 18%, respectively. Shoot to root DW ratio increas...

show abstract

Effect of Exogenous Nitrate on Anaerobic Metabolism in Excised Rice Roots

Cited by 47 publications

References 0 publications

Effects of Hypoxia on 13NH4+Fluxes in Rice Roots1

Effects of Hypoxia on 13NH4+Fluxes in Rice Roots1

Dynamics of Acetaldehyde Production during Anoxia and Post-Anoxia in Red Bell Pepper Studied by Photoacoustic Techniques

Prolonged root hypoxia effects on enzymes involved in nitrogen assimilation pathway in tomato plants

Contact Info

Product

Resources

About