Plant nitrogen assimilation and its regulation: a complex puzzle with missing pieces

Krapp, Anne

doi:10.1016/j.pbi.2015.05.010

Cited by 357 publications

(252 citation statements)

References 80 publications

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“…1). Considering that N and P are essential for constitution of cellular components such as proteins and nucleic acids (Rouached et al, 2010;Chiou and Lin, 2011;Simons et al, 2014;Krapp, 2015), reduction of N and P levels in the super ovary is consistent with the enhanced protein degradation mediated by cysteine-type peptidase activity during the green-yellow bud stage (Fig. 7C), and up-regulated signaling kinase activity during the yellow bud stage (Fig.…”

Section: Nutrient Supplies Played An Essential Role In Regulating Corsupporting

confidence: 70%

Integration of Hormonal and Nutritional Cues Orchestrates Progressive Corolla Opening

Sun

Zhao

et al. 2016

Plant Physiology

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Flower opening is essential for pollination and thus successful sexual reproduction; however, the underlying mechanisms of its timing control remain largely elusive. We identify a unique cucumber (Cucumis sativus) line '6457' that produces normal ovaries when nutrients are under-supplied, and super ovaries (87%) with delayed corolla opening when nutrients are oversupplied. Corolla opening in both normal and super ovaries is divided into four distinct phases, namely the green bud, green-yellow bud, yellow bud, and flowering stages, along with progressive color transition, cytological tuning, and differential expression of 14,282 genes. In the super ovary, cell division and cell expansion persisted for a significantly longer period of time; the expressions of genes related to photosynthesis, protein degradation, and signaling kinases were dramatically upregulated, whereas the activities of most transcription factors and stress-related genes were significantly down-regulated; concentrations of cytokinins (CKs) and gibberellins were higher in accordance with reduced cytokinin conjugation and degradation and increased expression of gibberellin biosynthesis genes. Exogenous CK application was sufficient for the genesis of super ovaries, suggesting a decisive role of CKs in controlling the timing of corolla opening. Furthermore, 194 out of 11,127 differentially expressed genes identified in pairwise comparisons, including critical developmental, signaling, and cytological regulators, contained all three types of cis-elements for CK, nitrate, and phosphorus responses in their promoter regions, indicating that the integration of hormone modulation and nutritional regulation orchestrated the precise control of corolla opening in cucumber. Our findings provide a valuable framework for dissecting the regulatory pathways for flower opening in plants.The flower is the most distinguishing organ in higher plants, and artists and scientists have been attracted to explore the mystery of flower structure and origin for decades. The evolution of flowering plants was greatly accelerated approximately 100 million years ago with the development of flowers, which were essential for recruiting animals to help distribute pollen and seeds (Danielson and Frommer, 2013). Flowers are produced from a specialized structure in the shoot tip called the shoot apical meristem, which consists of a pool of stem cells that continuously divide and replenish themselves (Fletcher et al., 1999). Morphologically, flowers are comprised of four basic structures arranged in concentric whorls: sepals in the outermost whorl 1, petals in whorl 2, stamens in whorl 3, and carpels in the innermost whorl 4. Bisexual flowers possess all four basic structures, while unisexual flowers lack one or more structures, usually the male organ stamen or the female organ carpel (Dellaporta and Calderon-Urrea, 1993). In flowering plants, approximately 90% species produce bisexual flowers, 6% species are dioecious with male and female flowers on separate plants, and 4% species a...

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Section: Nutrient Supplies Played An Essential Role In Regulating Corsupporting

confidence: 70%

Integration of Hormonal and Nutritional Cues Orchestrates Progressive Corolla Opening

Sun

Zhao

et al. 2016

Plant Physiology

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“…2 ) and ammonium (NH 4 + ) are the major inorganic nitrogen (N) forms absorbed by plant roots (Yuan et al, 2013;Krapp et al, 2014;Krapp, 2015). Upon absorption, the inorganic N forms are assimilated into the low-molecular organic N compound Gln and subsequently incorporated into proteins, nucleic acids, and a range of secondary metabolites (Hawkesford et al, 2012).…”

Section: Nitrate (Nomentioning

confidence: 99%

Cytosolic Glutamine Synthetase Gln1;2 Is the Main Isozyme Contributing to GS1 Activity and Can Be Up-Regulated to Relieve Ammonium Toxicity

et al. 2016

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Cytosolic GS1 (Gln synthetase) is central for ammonium assimilation in plants. High ammonium treatment enhanced the expression of the GS1 isogene Gln-1;2 encoding a low-affinity high-capacity GS1 protein in Arabidopsis (Arabidopsis thaliana) shoots. Under the same conditions, the expression of the high-affinity low-capacity isoform Gln-1;1 was reduced. The expression of Gln-1;3 did not respond to ammonium treatment while Gln-1;4 and Gln-1;5 isogenes in all cases were expressed at a very low level. Gln-2 was highly expressed in shoots but only at a very low level in roots. To investigate the specific functions of the two isogenes Gln-1;1 and Gln-1;2 in shoots for ammonium detoxification, single and double knock-out mutants were grown under standard N supply or with high ammonium provision. Phenotypes of the single mutant gln1;1 were similar to the wild type, while growth of the gln1;2 single mutant and the gln1;1:gln1;2 double mutant was significantly impaired irrespective of N regime. GS1 activity was significantly reduced in both gln1;2 and gln1;1:gln1;2. Along with this, the ammonium content increased while that of Gln decreased, showing that Gln-1;2 was essential for ammonium assimilation and amino acid synthesis. We conclude that Gln-1;2 is the main isozyme contributing to shoot GS1 activity in vegetative growth stages and can be up-regulated to relieve ammonium toxicity. This reveals, to our knowledge, a novel shoot function of Gln-1;2 in Arabidopsis shoots.

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“…6 In the Arabidopsis root, 6 different transporters have been shown to transport nitrate from the environment into root cells. 6,20 Under conditions of low external nitrate, uptake is mediated primarily by the high-affinity transporter, AtNRT2.1, and to a lesser degree by AtNRT2.2 and AtNRT2.4 [21][22][23] ; under nitrate starvation conditions uptake is mediated mainly by AtNRT2.5, with some contribution by AtNRT2.1. 24,25 At high concentrations of environmental nitrate, the dual-affinity transporter AtNPF6.3 (AtNRT1.1) and the low-affinity transporter AtNPF4.6 (AtNRT1.2; AtAIT1) come into play.…”

Section: Nitrate and Aba In Root Developmentmentioning

confidence: 99%

“…[28][29][30][31] The coupling of transport to sensing allows the cell to have an accurate perception of the amount of nitrate it is acquiring; once nitrate enters the cytoplasm, it can either be moved to the vacuole, exported from the cell or rapidly converted to other forms of inorganic nitrogen and subsequently assimilated, making accurate assessment of nitrate pools in the cytoplasm problematic. 20,32 The strongest case can be made for AtNPF6.3 being a transceptor, with a nitrate sensing role that can be uncoupled from transport. 30 Nitrate activation of ABA signaling by release of bioactive ABA from inactive stores Once nitrate is increased in the environment of the root, it triggers the gradual accumulation of ABA in the root tip, stimulating ABA signaling, and ultimately regulating first nitrate metabolism, then uptake ( Fig.…”

Section: Nitrate and Aba In Root Developmentmentioning

confidence: 99%

Environmental nitrate signals through abscisic acid in the root tip

Harris

Ondzighi‐Assoume

2017

Plant Signaling & Behavior

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Roots respond to changes in environmental nitrate with a localized stimulation of ABA levels in the root tip. This rise in ABA levels is due to the action of ER-localized b-GLUCOSIDASE 1, which releases bioactive ABA from the inactive ABA-glucose ester. The slow rise in root tip ABA levels stimulates expression of nitrate metabolic enzymes and simultaneously activates a negative feedback loop involving the protein phosphatase, ABI2, which reduces nitrate influx via the AtNPF6.3 transceptor. The rise in root-tip localized ABA also negatively regulates expression of the SCARECROW transcription factor, thus providing a sensitive mechanism for modulating root growth in response to environmental changes.

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Plant nitrogen assimilation and its regulation: a complex puzzle with missing pieces

Cited by 357 publications

References 80 publications

Integration of Hormonal and Nutritional Cues Orchestrates Progressive Corolla Opening

Integration of Hormonal and Nutritional Cues Orchestrates Progressive Corolla Opening

Cytosolic Glutamine Synthetase Gln1;2 Is the Main Isozyme Contributing to GS1 Activity and Can Be Up-Regulated to Relieve Ammonium Toxicity

Environmental nitrate signals through abscisic acid in the root tip

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