Intact Plastids Are Required for Nitrate- and Light-Induced Accumulation of Nitrate Reductase Activity and mRNA in Squash Cotyledons

Oelmüller, R.; Briggs, Winslow R.

doi:10.1104/pp.92.2.434

Cited by 48 publications

(27 citation statements)

References 27 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The state of developing plastids can affect the expression of nuclear genes, as evidenced in plants with defective chloroplasts due to mutations or chemical treatments (Bradbeer et al, 1979;May®eld and Taylor, 1984;Oelmuller and Mohr, 1986). These observations led to the proposal that communication between plastids and nucleus is mediated through a`plastid signal' (Oelmuller and Briggs, 1990). Genetic and biochemical studies using green algae have identi®ed chlorophyll precursors, tetrapyrroles, and the redox state of chloroplast as possible signals (Escoubas et al, 1995;Johanningmeier, 1988;Johanningmeier and Howell, 1984;Kropat et al, 1997).…”

Section: Introductionmentioning

confidence: 99%

The chlorate‐resistant and photomorphogenesis‐defective mutant cr88 encodes a chloroplast‐targeted HSP90

et al. 2003

View full text Add to dashboard Cite

SummaryThe cr88 mutant of Arabidopsis is a novel chlorate-resistant mutant that displays long hypocotyls in red light, but not in far red or blue light, and is delayed in the greening process. In cotyledons and young leaves, plastids are less developed compared with those of the wild type. In addition, a subset of light-regulated genes are under-expressed in this mutant. To understand the pleiotropic phenotypes of cr88, we isolated the CR88 gene through map-based cloning. We found that CR88 encodes a chloroplast-targeted 90-kDa heat shock protein (HSP90). The CR88 gene is expressed at highest levels during early post-germination stages and in leaves and reproductive organs. It is constitutively expressed but is also light and heat shock inducible. Chloroplast import experiments showed that the protein is localized to the stroma compartment of the chloroplast. The possible function of an HSP90 in the chloroplast and a plausible explanation of the pleiotropic phenotypes observed in cr88 are discussed.

show abstract

Section: Introductionmentioning

confidence: 99%

The chlorate‐resistant and photomorphogenesis‐defective mutant cr88 encodes a chloroplast‐targeted HSP90

et al. 2003

View full text Add to dashboard Cite

show abstract

“…The genetics and molecular biology of NR3 have been studied extensively (3, 5, 8,17,23), and the NR activity has been shown to be enhanced by cytokinins (16,18,19) (27). However, the mechanisms by which specific genes are regulated by multiple hormones are not well understood.…”

Section: Introductionmentioning

confidence: 99%

“…The genetics and molecular biology of NR3 have been studied extensively (3, 5, 8, 17,23), and the NR activity has been shown to be enhanced by cytokinins (16,18,19) and suppressed by ABA (16); thus, NR represents a convenient system to study the molecular function of these phytohormones. To clarify how these two hormones interact to modulate the NR gene expression, we have analyzed the effect of cytokinin and ABA on the levels of NR mRNA in vivo and on the transcript synthesized in isolated nuclei.…”

mentioning

confidence: 99%

Transcriptional Regulation of Nitrate Reductase mRNA Levels by Cytokinin-Abscisic Acid Interactions in Etiolated Barley Leaves

Lu¹,

Ertl²,

Chen³

1992

Plant Physiol.

View full text Add to dashboard Cite

To investigate the mechanisms by which the expression of a specific gene may be modulated by multiple hormones, the regulation of nitrate reductase (NR) mRNA levels by cytokinin and abscisic acid (ABA) was studied in etiolated barley (Hordeum vulgare L. cv Robust) leaves using a barley NR cDNA as a probe. Northem blot analyses of the levels of NR mRNA indicate that accumulation of the mRNA was enhanced by the cytokinin, benzyladenine (BA), and suppressed by ABA and that the hormonal effects on NR gene expression were responsive to dose concentrations (10-' to 10-4 molar). The NR mRNA levels were influenced by the BA/ABA concentration ratios, and the inhibition of the NR transcript levels by ABA was not totally reversed by addition of equal concentrations (10-to 10-4 molar) of BA. Nuclear runoff transcription studies showed that the level of transcription was suppressed by ABA, and addition of an equal concentration of BA partially reversed the ABA action. Thus, the interaction of cytokinin and ABA on NR gene expression is, at least in part, at the level of transcription.is, at least in part, at the level of transcription ( 13,21). Genes having related 5'-regulatory region DNA sequences are similarly regulated by either ABA (13, 29), GA3 ( 15), ethylene (2), or auxin (20), but the regulatory elements of genes responsive to these hormones have not been fully identified.The genetics and molecular biology of NR3 have been studied extensively (3, 5, 8,17,23), and the NR activity has been shown to be enhanced by cytokinins (16,18,19) (27). However, the mechanisms by which specific genes are regulated by multiple hormones are not well understood.The primary actions of cytokinins and ABA in the plant cells have not been fully elucidated at the molecular level. Cytokinins enhance and/or suppress the levels of specific mRNAs (4, 7, 9,19,26), and the enhancement has been shown to be mainly at the level of transcription (19) or posttranscription (9). ABA, like other phytohormones, induces, promotes, or suppresses the levels of specific mRNAs (1 1, 12, 21, 24), and the influence of ABA on gene expression Growth of PlantsBarley (Hordeum vulgare L. cv Robust ) seeds were soaked in water for 8 h and grown on sterile vermiculite at 25°C in the dark for 4 d. The seedlings (7-9 cm in length) were gently removed from the vermiculite and rinsed with water under green light. About 60 seedlings were placed into each 400-mL beaker containing 100 mL of 50 mm KNO3. The leaves were sprayed with 8 mL of the treatment solution (water or hormones dissolved in water) and placed at 25°C in darkness or cool-white fluorescent light (about 16 klx) for various time intervals. Excised leaves were frozen immediately in liquid nitrogen and stored at -700C. NR AssayThe following protocol was used to isolate and assay for NR in vitro. Barley leaves (3 g) were crushed in a mortar at 0 to 4°C in 3 mL of 25 mm potassium phosphate buffer (pH 7.5) containing 5 mm cysteine and 5 mM EDTA. The extract was strained through two layers of cheesecloth and...

show abstract

“…These include the cytosolic enzyme nitrate reductase (5), which is involved in nitrogen metabolism, and the peroxisomal enzymes glycolate oxidase and HPR (2,13,14), which are involved in photorespiration. Nitrate reductase transcript levels are reduced in the absence of intact chloroplasts, demonstrating that the chloroplasts exert their influence on this gene at a pretranslational level (23). The level at which a putative chloroplast factor affects expression of genes encoding glycolate oxidase and HPR was not previously known.…”

mentioning

confidence: 99%

Photooxidative Destruction of Chloroplasts Leads to Reduced Expression of Peroxisomal NADH-Dependent Hydroxypyruvate Reductase in Developing Cucumber Cotyledons

Schwartz¹,

Daniel²,

Becker³

1992

Plant Physiol.

View full text Add to dashboard Cite

Photooxidative destruction of chloroplasts by exposure of norflurazon-treated cucumber (Cucumis sativus L.) seedlings to white light leads to reduced levels of the nuclear-encoded, peroxisomal enzyme hydroxypyruvate reductase. The partial reduction in hydroxypyruvate reductase activity under photooxidative conditions is accompanied by reductions in levels of hydroxypyruvate reductase protein and transcript. The low level of hydroxypyruvate reductase gene expression in the dark is not affected by norflurazon, and nonphotooxidizing far-red light is able to induce significant increases in hydroxypyruvate reductase expression even in the presence of norflurazon. We conclude that intact plastids are required for maximal expression of hydroxypyruvate reductase in the light and that the plastids affect hydroxypyruvate reductase gene expression at a pretranslational level.

show abstract

Intact Plastids Are Required for Nitrate- and Light-Induced Accumulation of Nitrate Reductase Activity and mRNA in Squash Cotyledons

Cited by 48 publications

References 27 publications

The chlorate‐resistant and photomorphogenesis‐defective mutant cr88 encodes a chloroplast‐targeted HSP90

The chlorate‐resistant and photomorphogenesis‐defective mutant cr88 encodes a chloroplast‐targeted HSP90

Transcriptional Regulation of Nitrate Reductase mRNA Levels by Cytokinin-Abscisic Acid Interactions in Etiolated Barley Leaves

Photooxidative Destruction of Chloroplasts Leads to Reduced Expression of Peroxisomal NADH-Dependent Hydroxypyruvate Reductase in Developing Cucumber Cotyledons

Contact Info

Product

Resources

About