Light Regulation of Nitrate Reductase in Higher Plants: Which Photoreceptors are Involved?

Lillo, Cathrine; Appenroth, Klaus‐J.

doi:10.1055/s-2001-17732

Cited by 77 publications

(62 citation statements)

References 115 publications

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“…In previous studies, there was also little difference in electron flow between NO 3 2 and NH 4 + feedings in Arabidopsis and wheat (Triticum aestivum), which corresponded to lower leaf NO 3 2 reductase activity Rachmilevitch et al, 2004). Furthermore, nitrate reductase activity can decrease under lower light intensities, minimizing the impact of nitrate reduction to leaf energy balance under low PPFD (Pilgrim et al, 1993;Lillo and Appenroth, 2001).…”

Section: The Impact Of Nitrogen Form Treatmentmentioning

confidence: 99%

The Response of Cyclic Electron Flow around Photosystem I to Changes in Photorespiration and Nitrate Assimilation

Walker

Strand²,

Kramer³

et al. 2014

Plant Physiol.

133

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Photosynthesis captures light energy to produce ATP and NADPH. These molecules are consumed in the conversion of CO 2 to sugar, photorespiration, and NO 3 2 assimilation. The production and consumption of ATP and NADPH must be balanced to prevent photoinhibition or photodamage. This balancing may occur via cyclic electron flow around photosystem I (CEF), which increases ATP/NADPH production during photosynthetic electron transport; however, it is not clear under what conditions CEF changes with ATP/NADPH demand. Measurements of chlorophyll fluorescence and dark interval relaxation kinetics were used to determine the contribution of CEF in balancing ATP/NADPH in hydroponically grown Arabidopsis (Arabidopsis thaliana) supplied different forms of nitrogen (nitrate versus ammonium) under changes in atmospheric CO 2 and oxygen. Measurements of CEF were made under low and high light and compared with ATP/NADPH demand estimated from CO 2 gas exchange. Under low light, contributions of CEF did not shift despite an up to 17% change in modeled ATP/NADPH demand. Under high light, CEF increased under photorespiratory conditions (high oxygen and low CO 2 ), consistent with a primary role in energy balancing. However, nitrogen form had little impact on rates of CEF under high or low light. We conclude that, according to modeled ATP/ NADPH demand, CEF responded to energy demand under high light but not low light. These findings suggest that other mechanisms, such as the malate valve and the Mehler reaction, were able to maintain energy balance when electron flow was low but that CEF was required under higher flow.Photosynthesis must balance both the amount of energy harvested by the light reactions and how it is stored to match metabolic demands. Light energy is harvested by the photosynthetic antenna complexes and stored by the electron and proton transfer complexes as ATP and NADPH. It is used primarily to meet the energy demands for assimilating carbon (from CO 2 ) and nitrogen (from NO 3 2 and NH 4 + ; Keeling et al., 1976;Edwards and Walker, 1983;Miller et al., 2007). These processes require different ratios of ATP and NADPH, requiring a finely balanced output of energy in these forms. For example, if ATP were to be consumed at a greater rate than NADPH, electron transport would rapidly become limiting by the lack of NADP + , decreasing rates of proton translocation and ATP regeneration. Alternatively, if NADPH were consumed faster than ATP, proton translocation through ATP synthase would be reduced due to limiting ADP and the difference in pH between lumen and stroma would increase, restricting plastoquinol oxidation at the cytochrome b 6 f complex and initiating nonphotochemical quenching (Kanazawa and Kramer, 2002). The stoichiometric balancing of ATP and NADPH must occur rapidly, because pool sizes of ATP and NADPH are relatively small and fluxes through primary metabolism are large (Noctor and Foyer, 2000;Avenson et al., 2005;Cruz et al., 2005;Amthor, 2010).The balancing of ATP and NADPH supply is further complicated...

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Section: The Impact Of Nitrogen Form Treatmentmentioning

confidence: 99%

The Response of Cyclic Electron Flow around Photosystem I to Changes in Photorespiration and Nitrate Assimilation

Walker

Strand²,

Kramer³

et al. 2014

Plant Physiol.

133

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“…Post-translational regulation of NR is also strongly influenced by light (Lillo 1994, Lillo andAppenroth 2001). Most of what is known about posttranslational NR regulation, with few exceptions (Appenroth et al 2000), has been deduced from experiments using green leaves in which mainly effects of photosynthetic active light have been studied.…”

Section: Light and Post-transcriptional Regulation Of Nrmentioning

confidence: 99%

“…NR induction mediated by phytochrome was first reported in etiolated peas in 1972 (Jones and Sheard). Since then the involvement of phytochrome in NR induction was established for a large number of dicot and monocot plants (Sopory andSharma 1990, Lillo andAppenroth 2001). Light absorbed by phytochrome generally leads to increased levels of NR mRNA, protein and enzyme activity in etiolated plants.…”

Section: Nr and Phytochromementioning

confidence: 99%

“…Generally NR is inactivated in darkness by phosphorylation, and activated by dephosphorylation in the light Spill 1991, MacKintosh 1992). However, the system is more complex than simply phosphorylation and dephosphorylation because members of the 14-3-3 protein family also bind to phosphorylated NR (reviewed by Kaiser and Huber 2001, Lillo and Appenroth 2001, MacKintosh and Meek 2001). 14-3-3 proteins belong to a highly conserved protein family with regulatory roles in plant, fungal and mammalian cells (MacKintosh and Meek 2001).…”

Section: Light and Post-transcriptional Regulation Of Nrmentioning

confidence: 99%

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Light Regulation of Nitrate uptake, Assimilation and Metabolism

Lillo

2004

Plant Ecophysiology

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“…NR is regulated at both the transcription and posttranslational levels by multiple environmental and endogenous factors (Kaiser and Huber, 2001). Light, for instance, is a critical environmental cue that regulates both NR gene transcription and protein phosphorylation (Lillo and Appenroth, 2001). In the presence of nitrate, NR transcript and protein levels increase dramatically in deetiolating seedlings soon after exposure to illumination.…”

mentioning

confidence: 99%

Nitric Oxide, Ethylene, and Auxin Cross Talk Mediates Greening and Plastid Development in Deetiolating Tomato Seedlings

et al. 2016

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The transition from etiolated to green seedlings involves the conversion of etioplasts into mature chloroplasts via a multifaceted, light-driven process comprising multiple, tightly coordinated signaling networks. Here, we demonstrate that light-induced greening and chloroplast differentiation in tomato (Solanum lycopersicum) seedlings are mediated by an intricate cross talk among phytochromes, nitric oxide (NO), ethylene, and auxins. Genetic and pharmacological evidence indicated that either endogenously produced or exogenously applied NO promotes seedling greening by repressing ethylene biosynthesis and inducing auxin accumulation in tomato cotyledons. Analysis performed in hormonal tomato mutants also demonstrated that NO production itself is negatively and positively regulated by ethylene and auxins, respectively. Representing a major biosynthetic source of NO in tomato cotyledons, nitrate reductase was shown to be under strict control of both phytochrome and hormonal signals. A close NO-phytochrome interaction was revealed by the almost complete recovery of the etiolated phenotype of red light-grown seedlings of the tomato phytochrome-deficient aurea mutant upon NO fumigation. In this mutant, NO supplementation induced cotyledon greening, chloroplast differentiation, and hormonal and gene expression alterations similar to those detected in light-exposed wild-type seedlings. NO negatively impacted the transcript accumulation of genes encoding phytochromes, photomorphogenesis-repressor factors, and plastid division proteins, revealing that this free radical can mimic transcriptional changes typically triggered by phytochrome-dependent light perception. Therefore, our data indicate that negative and positive regulatory feedback loops orchestrate ethylene-NO and auxin-NO interactions, respectively, during the conversion of colorless etiolated seedlings into green, photosynthetically competent young plants.

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Light Regulation of Nitrate Reductase in Higher Plants: Which Photoreceptors are Involved?

Cited by 77 publications

References 115 publications

The Response of Cyclic Electron Flow around Photosystem I to Changes in Photorespiration and Nitrate Assimilation

The Response of Cyclic Electron Flow around Photosystem I to Changes in Photorespiration and Nitrate Assimilation

Light Regulation of Nitrate uptake, Assimilation and Metabolism

Nitric Oxide, Ethylene, and Auxin Cross Talk Mediates Greening and Plastid Development in Deetiolating Tomato Seedlings

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