scholarly journals Community shifts from eukaryote to cyanobacteria dominated phytoplankton: The role of mixing depth and light quality

2021 ◽  
Author(s):  
Maria Stockenreiter ◽  
Jana Isanta Navarro ◽  
Felicitas Buchberger ◽  
Herwig Stibor
Keyword(s):  
Light Quality ◽  
Mixing Depth ◽  
Community Shifts

The role of light quality of photoperiodic lighting on photosynthesis, flowering and metabolic profiling in Ranunculus asiaticus L.

2020 ◽  
Vol 170 (2) ◽  
pp. 187-201
Author(s):  
Giuseppe C. Modarelli ◽  
Carmen Arena ◽  
Giuseppe Pesce ◽  
Emilia Dell'Aversana ◽  
Giovanna M. Fusco ◽  
...  
Keyword(s):  
Metabolic Profiling ◽  
Light Quality ◽  
Ranunculus Asiaticus ◽  
Role Of Light

scholarly journals Plant-derived coumarins shape the composition of an Arabidopsis synthetic root microbiome

2019 ◽  
Vol 116 (25) ◽  
pp. 12558-12565 ◽  
Author(s):  
Mathias J. E. E. E. Voges ◽  
Yang Bai ◽  
Paul Schulze-Lefert ◽  
Elizabeth S. Sattely
Keyword(s):  
Microbial Community ◽  
Systematic Approach ◽  
Potential Role ◽  
Microbial Community Composition ◽  
Alkaline Soils ◽  
Arable Soils ◽  
Specialized Metabolites ◽  
Community Shifts ◽  
Root Microbiome

The factors that contribute to the composition of the root microbiome and, in turn, affect plant fitness are not well understood. Recent work has highlighted a major contribution of the soil inoculum in determining the composition of the root microbiome. However, plants are known to conditionally exude a diverse array of unique secondary metabolites, that vary among species and environmental conditions and can interact with the surrounding biota. Here, we explore the role of specialized metabolites in dictating which bacteria reside in the rhizosphere. We employed a reduced synthetic community (SynCom) of Arabidopsis thaliana root-isolated bacteria to detect community shifts that occur in the absence of the secreted small-molecule phytoalexins, flavonoids, and coumarins. We find that lack of coumarin biosynthesis in f6′h1 mutant plant lines causes a shift in the root microbial community specifically under iron deficiency. We demonstrate a potential role for iron-mobilizing coumarins in sculpting the A. thaliana root bacterial community by inhibiting the proliferation of a relatively abundant Pseudomonas species via a redox-mediated mechanism. This work establishes a systematic approach enabling elucidation of specific mechanisms by which plant-derived molecules mediate microbial community composition. Our findings expand on the function of conditionally exuded specialized metabolites and suggest avenues to effectively engineer the rhizosphere with the aim of improving crop growth in iron-limited alkaline soils, which make up a third of the world’s arable soils.

scholarly journals The Role of Leaves in Photocontrol of Flower Bud Abscission in Hibiscus rosa-sinensis L. `Nairobi'

2000 ◽  
Vol 125 (1) ◽  
pp. 31-35 ◽  
Author(s):  
Uulke van Meeteren ◽  
Annie van Gelder
Keyword(s):  
Light Quality ◽  
Light Exposure ◽  
Red Light ◽  
Light Conditions ◽  
Flower Bud ◽  
Light Emitting ◽  
Hibiscus Rosa Sinensis ◽  
Number Of Leaves ◽  
Whole Plants

When compared with exposure to darkness, exposing Hibiscus rosa-sinensis L. `Nairobi' plants to red light (635 to 685 nm, 2.9 μmol·m-2·s-1) delayed flower bud abscission, while exposure to far-red light (705 to 755 nm, 1.7 μmol·m-2·s-1) accelerated this process. Flower bud abscission in response to light quality appears to be controlled partly by the presence of leaves. The delay of bud abscission was positively correlated to the number of leaves being exposed to red light. Excluding the flower buds from exposure to red or far-red light, while exposing the remaining parts of the plants to these light conditions, did not influence the effects of the light exposure on bud abscission. Exposing only the buds to red light by the use of red light-emitting diodes (0.8 μmol·m-2·s-1) did not prevent dark-induced flower bud abscission. Exposing the whole plants, darkness or far-red light could only induce flower bud abscission when leaves were present; bud abscission was totally absent when all leaves were removed. To prevent flower bud abscission, leaves had to be removed before, or at the start of, the far-red light treatment. These results suggest that in darkness or far-red light, a flower bud abscission-promoting signal from the leaves may be involved.

scholarly journals Stomatal opening and growth in tomato seedlings treated with different proportions of red and blue light

2019 ◽  
Vol 99 (5) ◽  
pp. 688-700 ◽  
Author(s):  
Junwei Yang ◽  
Tingting Liang ◽  
Lu Liu ◽  
Tonghua Pan ◽  
Zhirong Zou
Keyword(s):  
Blue Light ◽  
Light Quality ◽  
Red Light ◽  
Chloroplast Ultrastructure ◽  
Net Photosynthesis ◽  
Dry Weight ◽  
Stomatal Opening ◽  
Detailed Knowledge ◽  
Tomato Seedlings

Stomatal opening/closure plays a key role in balancing a plant’s need to conserve water, while still allowing for the exchange of photosynthetic and respiratory gasses with the atmosphere. Stomatal opening/closure can be induced by differences in light quality but a detailed knowledge of the role of light in stomatal regulation in tomato is limited. In this study, we evaluated red and blue light-dependent stomatal opening processes in tomato seedlings and explored the mechanisms involved using different light-quality treatments. After 10 h of darkness, tomato seedlings were subjected to the following five treatments: monochromatic red light (R), 33% blue (2R1B), 50% blue (1R1B), 67% blue (1R2B), and monochromatic blue light (B) at 200 μmol m−2s−1light intensity. The highest stomatal conductance recorded were for 1R1B. Stomatal aperture under 1R1B showed a 92.8% increase after 15 min and a 28.6% increase after 30 min compared with under R alone. Meanwhile, the study shows that the expressions of the plasma membrane H+-ATPase in the leaf were regulated by different proportions of blue light. The results show that the expressions of HA1 and HA4 increased under 1R1B and 1R2B after 15 min of exposure compared with under R alone. Under 1R1B, our results also show net photosynthesis increased compared with R and B after longer treatments, which may be related to chloroplast ultrastructure, and leaf dry weight increased compared with under 1R2B or B alone, but there were no differences under the R and 2R1B light treatments.

scholarly journals Effects of Light Quality and Phytochrome Form on Melatonin Biosynthesis in Rice

Biomolecules ◽  
2020 ◽  
Vol 10 (4) ◽  
pp. 523
Author(s):  
Ok Jin Hwang ◽  
Kiyoon Kang ◽  
Kyoungwhan Back
Keyword(s):  
Light Quality ◽  
Receptor Expression ◽  
Tryptophan Decarboxylase ◽  
Rice Seedlings ◽  
Light Emitting ◽  
Melatonin Synthesis ◽  
Cadmium Treatment ◽  
Treatment Experiment ◽  
Melatonin Production

Light is an important factor influencing melatonin synthesis in response to cadmium treatment in rice. However, the effects of light quality on, and the involvement of phytochrome light receptors in, melatonin production have not been explored. In this study, we used light-emitting diodes (LEDs) to investigate the effect of light wavelength on melatonin synthesis, and the role of phytochromes in light-dependent melatonin induction in rice. Upon cadmium treatment, peak melatonin production was observed under combined red and blue (R + B) light, followed by red (R) and blue light (B). However, both far-red (FR) LED light and dark treatment (D) failed to induce melatonin production. Similarly, rice seedlings grown under the R + B treatment showed the highest melatonin synthesis, followed by those grown under B and R. These findings were consistent with the results of our cadmium treatment experiment. To further confirm the effects of light quality on melatonin synthesis, we employed rice photoreceptor mutants lacking functional phytochrome genes. Melatonin induction was most inhibited in the phytochrome A mutant (phyA) followed by the phyB mutant under R + B treatment, whereas phyB produced the least amount of melatonin under R treatment. These results indicate that PhyB is an R light receptor. Expression analyses of genes involved in melatonin biosynthesis clearly demonstrated that tryptophan decarboxylase (TDC) played a key role in phytochrome-mediated melatonin induction when rice seedlings were challenged with cadmium.

UV-B induces usnic acid in reindeer lichens

2006 ◽  
Vol 38 (5) ◽  
pp. 477-485 ◽  
Author(s):  
Line NYBAKKEN ◽  
Riitta JULKUNEN-TIITTO
Keyword(s):  
Light Quality ◽  
Usnic Acid ◽  
Secondary Compounds ◽  
Lichen Species ◽  
Growth Chamber ◽  
Simulated Herbivory ◽  
Light Regimes ◽  
Controlled Conditions ◽  
Reindeer Lichens

Induction of secondary compounds in three reindeer lichens (Cladonia arbuscula, C. rangiferina and C. stellaris) was studied under controlled conditions in a growth chamber. Acetone rinsed (secondary compounds removed) lichen mats were subjected to three light regimes (PAR, PAR+UV-A and PAR+UV-A+UV-B), each combined with simulated herbivory (clipping). After 4 weeks, lichen extracts were analyzed by HPLC for any synthesized secondary compounds. UV-B induced the synthesis of usnic acid in C. arbuscula and C. stellaris and melanic pigments in C. rangiferina. Atranorin, fumarprotocetraric acid and perlatolic acid were not influenced by light quality. None of the identified compounds were significantly influenced by clipping. In conclusion, all three lichen species responded to UV-B radiation by developing cortical UV-B absorbing pigments that might function as protective screens. However, the experiment did not produce evidence for a herbivore-deterrent role of compounds studied.

scholarly journals Regulation of Chrysanthemum Growth by Spectral Filters

1992 ◽  
Vol 117 (3) ◽  
pp. 481-485 ◽  
Author(s):  
Nihal C. Rajapakse ◽  
John W. Kelly
Keyword(s):  
Light Quality ◽  
Leaf Size ◽  
Experimental Period ◽  
Internode Length ◽  
Photon Flux ◽  
Average Height ◽  
Dry Matter Accumulation ◽  
Water Control ◽  
Spectral Filters

The role of light quality and quantity in regulating growth of vegetative Dendranthema × grandiflorum (Ramat.) Kitamura was evaluated using CuSO4 solutions and water (control) as spectral filters. Copper sulfate filters increased the red (R): far-red (FR) and the blue (B): R ratios (R = 600 to 700 nm; FR = 700 to 800 nm; B = 400 to 500 urn) of transmitted light. Photosynthetic photon flux (PPF) under 4%, 8% and 16% CuSO4 filters was reduced 26%, 36%, and 47%, respectively, from natural irradiance in the greenhouse, which averaged ≈ 950 μmol·m-2·s-1. Control treatments were shaded with Saran plastic film to ensure equal PPF as the corresponding C uSO4 chamber. Average daily maxima and minima were 26 ± 3C and 16 ± 2C. At the end of the 4-week experimental period, average height and internode length of plants grown under CuSO4 filters were ≈ 40% and 34% shorter than those of plants grown under control filter. Reduction in plant height and internode length was apparent within 1 week after the beginning of treatment. Total leaf area (LA) was reduced by 32% and leaf size (LS) was reduced by 24% under CuSO4 filters. Specific leaf weight (SLW) was higher under CuSO4 filters than for the controls. Irradiance transmitted through CuSO4 filters reduced fresh and dry leaf weights by 30%. Fresh and dry stem weights of plants grown under CuSO4 filters were 60% lower than those of controls. Relative dry matter accumulation into leaves was increased in plants grown under CuSO4 filters while it was reduced in stems. A single application of GA3 before irradiation partially overcame the height reduction under CuSO4 filters, suggesting GA biosynthesis/action may be affected by light quality. Our results imply that alteration of light quality could be used to control chrysanthemum growth as an alternative method to conventional control by chemical growth regulators. Chemical names used: gibberellic acid (GA)

scholarly journals Lotus japonicus symbiosis signaling genes and their role in the establishment of root-associated bacterial and fungal communities

2019 ◽  
Author(s):  
Rafal Zgadzaj ◽  
Thorsten Thiergart ◽  
Zoltán Bozsóki ◽  
Ruben Garrido-Oter ◽  
Simona Radutoiu ◽  
...  
Keyword(s):  
Lotus Japonicus ◽  
Am Fungi ◽  
Internal Transcribed Spacers ◽  
Natural Soil ◽  
Host Genotype ◽  
Symbiotic Relationships ◽  
Community Profiling ◽  
Community Shifts ◽  
Wild Legume

AbstractThe wild legume Lotus japonicus engages in mutualistic symbiotic relationships with arbuscular mycorrhiza (AM) fungi and nitrogen-fixing rhizobia. Using plants grown in natural soil and community profiling of bacterial 16S rRNA genes and fungal internal transcribed spacers (ITS), we examined here the role of the Lotus symbiosis genes RAM1, NFR5, SYMRK, and CCaMK in structuring bacterial and fungal root-associated communities. We found host genotype-dependent community shifts in the root and rhizosphere compartments that were mainly confined to bacteria in nfr5 or fungi in ram1 mutants, whilst symRK and ccamk plants displayed major changes across both microbial kingdoms. We observed in all AM mutant roots an almost complete depletion of a large number of Glomeromycota taxa that was accompanied by a concomitant enrichment of Helotiales and Nectriaceae fungi, suggesting compensatory niche replacement within the fungal community. A subset of Glomeromycota whose colonization is strictly dependent on the common symbiosis pathway was retained in ram1 mutants, indicating that RAM1 is dispensable for intraradical colonization by some Glomeromycoyta fungi. However, intraradical colonization by certain Burkholderiaceae taxa is dependent on AM root infection, thereby revealing a microbial interkingdom interaction. Our findings imply a broad role for Lotus symbiosis genes in structuring the root microbiota.

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