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At least 19 recordsLinked to original sources
PubMed1989

Post-transcriptional control of plastid mRNA accumulation during adaptation of chloroplasts to different light quality environments.

The adaptation of germinating spinach seedlings to yellow and red light was studied and compared with plants grown in white light. Spinach chloroplasts isolated from cotyledons and leaves of yellow and white light-grown plants showed similar membrane structures and compositions, while chloroplasts from plants grown in red light have significant adaptive changes. Based on an equal amount of chlorophyll, these changes include a reduction in the number of photosystem I complexes, an increase of photosystem II antenna size, and an increased ratio of stacked to unstacked membranes in red light-adapted chloroplasts. The decrease in the number of photosystem I complexes per unit of chlorophyll in these chloroplasts was qualitatively correlated with an approximately 10-fold decrease in the level of the psaA mRNA encoding the photosystem I 65-kilodalton to 70-kilodalton chlorophyll apoprotein, as well as with a differential decrease in mRNA levels of other photosynthetic proteins. Light quality adaptations do not significantly affect the plastid to nuclear DNA ratio or the overall chloroplast transcription activity. The relative transcriptional activities of 10 plastid genes, as determined by run-on transcription assays, are similar in chloroplasts from cotyledons and leaves of plants grown under the three light qualities. Only the psaA gene shows a 30% to 40% decrease in transcription activity in chloroplasts of plants adapted to red light. This decrease in psaA transcription activity, however, cannot fully account for the decrease of its mRNA level. We conclude, therefore, that post-transcriptional mechanisms are primarily responsible for the control of differential chloroplast mRNA accumulation in light quality adaptations.

Adaptation, Physiological↗
PubMed1978

Effect of light quality on the photoinduction of carotenoid synthesis in Verticillim agaricinum.

The action spectrum of photoinduction of carotenoid biosynthesis in Verticillium agaricinum has a high peak in the near-UV region with very small peaks in the blue, yellow and red regions. This suggests that neither a flavoprotein nor a carotenoid could be the photoreceptor, but a new unknown pigment system. Sporulation however is not photoregulated and is unaffected by light in the near-UV region. So, mycochrome cannot be implicated in the sporulation of this fungus. Further, sporulation and carotenogenesis must be under separate regulatory control in this organism, but not necessarily so in other organisms.

Carotenoids↗
PubMed1970

Effect of photoperiod and end-of-day light quality on alkaloids and phenolic compounds of tobacco.

Tobacco plants (Nicotiana tabacum L.) were grown on long or short photoperiods followed by 5 minutes of red or far red radiation each day. Plants that received 16-hour photoperiods had a significantly higher concentration of total alkaloids and total phenolics than those that received 8-hour photoperiods. Significantly higher total alkaloid content was found in plants that received red rather than far red radiation last each day. Within each photoperiod, plants that received far red had higher concentrations of soluble phenols, particularly of chlorogenic acid. The interactions among these variables upon alkaloid and phenolic contents are discussed.

Alkaloids↗
PubMed1990

The control of root, vegetative shoot and flower morphogenesis in tobacco thin cell-layer explants (TCLs).

Thin cell-layer explants (TCLs) have been proposed as favorable tissues for the study of root, vegetative shoot and flower formation. We tested the effects of pH, light quality, light quantity, and IBA and kinetin concentrations on the morphogenesis of TCLs cultured individually on a liquid medium. Alterations of the amounts of exogenously supplied IBA and kinetin were sufficient to induce the formation of roots, vegetative shoots and flowers on TCLs cultured on otherwise identical media. The type and number of organs formed were sensitive to the intensity of light (55, 75, 100 and 120 muEinsteins m-2 sec-1) under which TCLs were grown. Evidence was obtained that the effects of light on TCL morphogenesis were associated with photochemical degradation of IBA in the medium. Evaluation of the organogenesis that occurred in TCLs cultured on a medium containing a range of IBA and kinetin concentrations showed that the number and type of organs formed, and overall growth, were dependent upon the initial concentrations of auxin and cytokinin. We have developed the TCL culture system into a sensitive and reproducible bioassay for the study of morphogenesis. The advantages of using the TCL morphogenesis bioassay for the identification and study of molecules (e.g. cell wall oligosaccharides) that may regulate morphogenesis are discussed.

Adenine↗
PubMed2025

Multi-Omics Analyses Reveal the Red and Far-Red Light Combination Enhancing Heterologous Protein and Metabolite Production in Nicotiana benthamiana.

Transient expression of exogenous protein in Nicotiana benthamiana leaves via agroinfiltration offers a rapid and efficient platform for functional gene discovery and heterologous production of valuable eukaryotic proteins and metabolites. Though light quality is an important factor for plant photomorphogenesis, its impact on the efficiency of transient expression remains unexplored. In this study, we examined the influence of five representative light qualities with varying wavelength mix on the N. benthamiana growth and recombinant green fluorescent protein (GFP) production. Plants with red and far-red light treatment (LED-red) showed the highest GFP expression, 57.4% higher than white light. Further study showed that a higher dosage of post-infiltration Agrobacterium and the resulting increase in the number of transcripts contribute to the expression rate enhancement. Moreover, as for exogenous metabolites, a 76.5% increase of accumulated taxadiene was also observed in LED-red group. Integrated transcriptomic, proteomic and metabolomic revealed that LED-red plants reduced the resistance pathways before infiltration, inducing a higher dosage of post-agroinfiltration Agrobacterium. Our results suggest that N. benthamiana grown under LED-red creates a more favorable environment for Agrobacterium growth, enhancing heterologous protein and metabolite production. This study highlights the potential utilization of light quality as an implementable tool in plant synthetic biology.

Nicotiana↗
PubMed1977

Occurrence and nature of chromatic adaptation in cyanobacteria.

Forty-four axenic strains of cyanobacteria that synthesize phycoerythrin were screened to ascertain the effect of light quality on pigment synthesis. Cellular pigment compositions were determined after photoautotrophic growth with low light fluxes (7.0 X 10(2) ergs/cm2 per s) of green, red, and white light, and in the case of facultative heterotrophs, after dark growth at the expense of sugars. Twelve strains did not adapt chromatically: the cells contained fixed proportions of phycoerythrin, phycocyanin, and allophycocyanin under the growth conditions used. In the remaining strains, the cellular ratio of phycoerythrin to phycocyanin was much higher after growth in green than in red light. Quantitative data on the cellular pigment contents, supplemented by measurements of the differential rates of pigment synthesis on representative strains, show that chromatic adaptation may involve a light-induced modulation either of phycoerythrin synthesis alone (7 strains) or of both phycoerythrin and phycocyanin synthesis (25 strains). Facultative hetrotrophs able to adapt chromatically have a phycobiliprotein composition after dark growth which closely resembles that after growth in red light. Light quality does not affect the differential rate of chlorophyll synthesis. The physiological and taxonomic implications of these findings are discussed.

Adaptation, Physiological↗
PubMed1990

Regulation of nuclear genes encoding chloroplast proteins in transgenic plants.

Transgenic plants have been particularly useful in studying nuclear genes encoding for photosynthetic functions. The expression of these genes and their chimeric constructs in transgenic plants faithfully mimics their natural counterparts. The use of sensitive chimeric reporter genes has enabled localizing the activity of genes encoding photosynthetic proteins to individual cells. Cab and rbcS transgenes have been shown to retain sensitivity to light quality, which is modulated by phytochrome. Conditional light activation under the influence of a circadian rhythm has been shown for Cab transgenes. Transgenic plants containing truncated promoters have helped delineate cis-regulatory positive and negative elements involved in light-mediated transcriptional induction and tissue specificity.

Base Sequence↗
PubMed1983

[Effect of light on the development of Saccobolus platensis].

The ascomycetous fungi Saccobolus platensis requires light for apothecial production. Photoinduction could be accomplished by continuous light and also by minor light periods. When apothecia were photoinduced by single 24 hour photoperiods, the effect varied according to the stage of development of the mycelium: it was most photoreceptive at the 5th day of growth. At this stage a single 6 hour irradiation was enough to induce 50% fructifications of the control (continuous light). After photoinduction, protoapothecia reached maturity independently of light treatment. Light quality influenced both apothecial number and size. Near ultraviolet light was the most effective for the induction of apothecia, followed by blue light; the maximum apothecial size was reached under blue light.

Ascomycota↗