Phototropin is partly involved in blue-light-mediated stem elongation, flower initiation, and leaf expansion: A comparison of phenotypic responses between wild Arabidopsis and its phototropin mutants

2020 ◽  
Vol 171 ◽  
pp. 103967 ◽  
Author(s):  
Yun Kong ◽  
Youbin Zheng
Keyword(s):  
Blue Light ◽  
Stem Elongation ◽  
Leaf Expansion ◽  
Flower Initiation ◽  
Phenotypic Responses

scholarly journals Low-activity Cryptochrome 1 Plays a Role in Promoting Stem Elongation and Flower Initiation of Mature Arabidopsis under Blue Light Associated with Low Phytochrome Activity

2021 ◽  
Author(s):  
Yun Kong ◽  
Youbin Zheng
Keyword(s):  
Transgenic Plants ◽  
High Activity ◽  
Blue Light ◽  
Stem Elongation ◽  
Flower Initiation ◽  
Wild Type ◽  
Cryptochrome 1 ◽  
Low Activity

To clarify whether cryptochrome contributes to stem elongation and flowering promoted by blue lights associated with low phytochrome activity, wild-type Arabidopsis was compared with its cryptochrome-deficient mutants and cryptochrome-overexpressing transgenic plants. Results indicated that the promotion effects were mainly related to low CRY1 activity, despite partial involvement of high-activity CRY2.

Phytochrome contributes to blue-light-mediated stem elongation and flower initiation in mature Arabidopsis thaliana plants

2021 ◽  
Author(s):  
Yun Kong ◽  
Youbin Zheng
Keyword(s):  
Arabidopsis Thaliana ◽  
Blue Light ◽  
Stem Elongation ◽  
Growth Trait ◽  
Stem Length ◽  
Photon Flux ◽  
Flower Initiation ◽  
Shade Avoidance ◽  
Wild Type ◽  
Avoidance Responses

To examine whether phytochromes contribute to blue-light-mediated stem elongation, plant phenotypic responses were investigated in wild type Arabidopsis thaliana (Col-0), and its quintuple phytochrome (phyA phyB phyC phyD phyE) mutant plants under the following light treatments: (1) R, a pure red light from 660-nm LED; (2) B, a pure blue light from 455-nm LED; (3) BR, a impure blue light from LED combination of 94% B and 6% R; and (4) BRF, another impure blue light from LED combination of BR and 6 µmol m−2 s−1 of FR (735 nm). A photosynthetic photon flux density of ≈100 μmol m−2 s−1 was provided for all the light treatments. The calculated phytochrome photoequilibrium was 0.89, 0.50, 0.69, and 0.60 for R, B, BR, and BRF, respectively, indicating a higher phytochrome activity under R and BR than B and BRF. After 18 days of light treatment, B or BRF increased main stem length in wild-type plants compared with R, but BR had an inhibition effect similar to R. Also, B and BRF relative to R or BR induced earlier flowering and reduced leaf size in wild type plants, showing typical shade-avoidance responses. In phytochrome-deficient mutant plants, the above shade-avoidance responses were inhibited under B or BRF. However, hypocotyl length, a growth trait characterizing the de-etiolation stage, was reduced under B, BR and BRF vs. R regardless of phytochrome absence. These findings suggest that for mature Arabidopsis plants, phytochrome plays a role in blue-light-mediated stem elongation and the associated shade-avoidance responses.

scholarly journals Spectral Effects of Three Types of White Light-emitting Diodes on Plant Growth and Development: Absolute versus Relative Amounts of Blue Light

HortScience ◽  
2013 ◽  
Vol 48 (4) ◽  
pp. 504-509 ◽  
Author(s):  
Kevin R. Cope ◽  
Bruce Bugbee
Keyword(s):  
Plant Growth ◽  
Blue Light ◽  
Plant Development ◽  
Growth And Development ◽  
Stem Elongation ◽  
Leaf Expansion ◽  
Light Sources ◽  
Plant Growth And Development ◽  
Light Emitting ◽  
White Leds

Light-emitting diodes (LEDs) are a rapidly developing technology for plant growth lighting and have become a powerful tool for understanding the spectral effects of light on plants. Several studies have shown that some blue light is necessary for normal growth and development, but the effects of blue light appear to be species-dependent and may interact with other wavelengths of light as well as photosynthetic photon flux (PPF). We report the photobiological effects of three types of white LEDs (warm, neutral, and cool, with 11%, 19%, and 28% blue light, respectively) on the growth and development of radish, soybean, and wheat. All species were grown at two PPFs (200 and 500 μmol·m−2·s−1) under each LED type, which facilitated testing the effect of absolute (μmol photons per m−2·s−1) and relative (percent of total PPF) blue light on plant development. Root and shoot environmental conditions other than light quality were uniformly maintained among six chambers (three lamp types × two PPFs). All LEDs had similar phytochrome photoequilibria and red:far red ratios. Blue light did not affect total dry weight (DW) in any species but significantly altered plant development. Overall, the low blue light from warm white LEDs increased stem elongation and leaf expansion, whereas the high blue light from cool white LEDs resulted in more compact plants. For radish and soybean, absolute blue light was a better predictor of stem elongation than relative blue light, but relative blue light better predicted leaf area. Absolute blue light better predicted the percent leaf DW in radish and soybean and percent tiller DW in wheat. The largest percentage differences among light sources occurred in low light (200 μmol·m−2·s−1). These results confirm and extend the results of other studies indicating that light quantity and quality interact to determine plant morphology. The optimal amount of blue light likely changes with plant age because plant communities balance the need for rapid leaf expansion, which is necessary to maximize radiation capture, with prevention of excessive stem elongation. A thorough understanding of this interaction is essential to the development of light sources for optimal plant growth and development.

scholarly journals Photosynthesis, Morphology, Yield, and Phytochemical Accumulation in Basil Plants Influenced by Substituting Green Light for Partial Red and/or Blue Light

HortScience ◽  
2019 ◽  
Vol 54 (10) ◽  
pp. 1769-1776 ◽  
Author(s):  
Haijie Dou ◽  
Genhua Niu ◽  
Mengmeng Gu
Keyword(s):  
Antioxidant Capacity ◽  
Blue Light ◽  
Stem Elongation ◽  
Green Light ◽  
Leaf Expansion ◽  
Leaf Thickness ◽  
Working Environment ◽  
Photon Flux ◽  
Plant Yield ◽  
Petiole Elongation

Green light penetrates deeper into the plant canopy because of its high transmittance and reflectance, and may potentially increase light interception and whole-canopy photosynthesis, whereas red and blue light is absorbed primarily by upper leaves. Moreover, green light induces shade avoidance responses and regulates secondary metabolism in plants. In this study, we investigated the effects of substituting partial red and/or blue light with green light on plant growth and development in basil (Ocimum basilicum) ‘Improved Genovese Compact’ (green) and ‘Red Rubin’ (purple) plants. There were four treatments: one combined red and blue (R&B) light treatment, R76B24 [the proportion of red (R) and blue (B) light was 76% and 24%, respectively]; and three green (G) light treatments—R44B24G32, R74B16G10, and R42B13G45—with green light proportions of 32%, 10%, and 45%, respectively. The experiment was conducted in a growth room and the photosynthetic photon flux density (PPFD) of all treatments was set at 220 μmol·m−2·s−1 with a 16-h photoperiod. Plants were subirrigated as needed using a nutrient solution with an electrical conductivity (EC) of 2.0 dS·m−1 and a pH of 6.0. The net photosynthetic rate (Pn) in lower leaves was unaffected by green light treatments in green basil plants, whereas in purple basil plants it increased by 59% and 45% under treatments R44B24G32 and R74B16G10, respectively, compared with the combined R&B light. In green basil plants, treatments R44B24G32 and R42B13G45 induced stem elongation, but green light treatments showed no effects on petiole elongation, leaf expansion, leaf thickness, or plant yield. In purple basil plants, treatments R44B24G32 and R42B13G45 induced stem elongation and decreased leaf thickness and plant yield, but only the R42B13G45 treatment induced petiole elongation, and green light treatments showed no effects on leaf expansion. Concentrations of anthocyanin, phenolics, and flavonoids, and antioxidant capacity in green basil leaves showed no differences between treatments R76B24 and R44B24G32, but decreased under treatments R74B16G10 and R42B13G45. Concentrations of phenolics and flavonoids, and antioxidant capacity in purple basil leaves showed no differences between treatments R76B24 and R74B16G10, but decreased under treatments R44B24G32 and R42B13G45. Combining plant yield, nutritional values, and the working environment for growers, a white light with low green light proportion (≈10%) is recommended for basil production in a controlled environment.

scholarly journals Does Green Really Mean Go? Increasing the Fraction of Green Photons Promotes Growth of Tomato but Not Lettuce or Cucumber

Plants ◽  
2021 ◽  
Vol 10 (4) ◽  
pp. 637
Author(s):  
Paul Kusuma ◽  
Boston Swan ◽  
Bruce Bugbee
Keyword(s):  
Leaf Area ◽  
Stem Elongation ◽  
Wavelength Region ◽  
Sole Source ◽  
Dry Mass ◽  
Leaf Expansion ◽  
Photon Flux ◽  
Shade Avoidance ◽  
Crop Species ◽  
Blue Region

The photon flux in the green wavelength region is relatively enriched in shade and the photon flux in the blue region is selectively filtered. In sole source lighting environments, increasing the fraction of blue typically decreases stem elongation and leaf expansion, and smaller leaves reduce photon capture and yield. Photons in the green region reverse these blue reductions through the photoreceptor cryptochrome in Arabidopsis thaliana, but studies in other species have not consistently shown the benefits of photons in the green region on leaf expansion and growth. Spectral effects can interact with total photon flux. Here, we report the effect of the fraction of photons in the blue (10 to 30%) and green (0 to 50%) regions at photosynthetic photon flux densities of 200 and 500 µmol m−2 s−1 in lettuce, cucumber and tomato. As expected, increasing the fraction of photons in the blue region consistently decreased leaf area and dry mass. By contrast, large changes in the fraction of photons in the green region had minimal effects on leaf area and dry mass in lettuce and cucumber. Photons in the green region were more potent at a lower fraction of photons in the blue region. Photons in the green region increased stem and petiole length in cucumber and tomato, which is a classic shade avoidance response. These results suggest that high-light crop species might respond to the fraction of photons in the green region with either shade tolerance (leaf expansion) or shade avoidance (stem elongation).

scholarly journals Floral Induction in the Short-Day Plant Chrysanthemum Under Blue and Red Extended Long-Days

2021 ◽  
Vol 11 ◽  
Author(s):  
Malleshaiah SharathKumar ◽  
Ep Heuvelink ◽  
Leo F. M. Marcelis ◽  
Wim van Ieperen
Keyword(s):  
Blue Light ◽  
Floral Induction ◽  
Sole Source ◽  
Solar Light ◽  
Growth Chamber ◽  
Flower Initiation ◽  
Dependent Manner ◽  
Led Light ◽  
Short Day ◽  
Short Days

Shorter photoperiod and lower daily light integral (DLI) limit the winter greenhouse production. Extending the photoperiod by supplemental light increases biomass production but inhibits flowering in short-day plants such as Chrysanthemum morifolium. Previously, we reported that flowering in growth-chamber grown chrysanthemum with red (R) and blue (B) LED-light could also be induced in long photoperiods by applying only blue light during the last 4h of 15h long-days. This study investigates the possibility to induce flowering by extending short-days in greenhouses with 4h of blue light. Furthermore, flower induction after 4h of red light extension was tested after short-days RB-LED light in a growth-chamber and after natural solar light in a greenhouse. Plants were grown at 11h of sole source RB light (60:40) in a growth-chamber or solar light in the greenhouse (short-days). Additionally, plants were grown under long-days, which either consisted of short-days as described above extended with 4h of B or R light to long-days or of 15h continuous RB light or natural solar light. Flower initiation and normal capitulum development occurred in the blue-extended long-days in the growth-chamber after 11h of sole source RB, similarly as in short-days. However, when the blue extension was applied after 11h of full-spectrum solar light in a greenhouse, no flower initiation occurred. With red-extended long-days after 11h RB (growth-chamber) flower initiation occurred, but capitulum development was hindered. No flower initiation occurred in red-extended long-days in the greenhouse. These results indicate that multiple components of the daylight spectrum influence different phases in photoperiodic flowering in chrysanthemum in a time-dependent manner. This research shows that smart use of LED-light can open avenues for a more efficient year-round cultivation of chrysanthemum by circumventing the short-day requirement for flowering when applied in emerging vertical farm or plant factories that operate without natural solar light. In current year-round greenhouses’ production, however, extension of the natural solar light during the first 11 h of the photoperiod with either red or blue sole LED light, did inhibit flowering.

Effects of early drought and transplanting on the subsequent development of the tobacco plant

1968 ◽  
Vol 19 (1) ◽  
pp. 47 ◽  
Author(s):  
JM Hopkinson
Keyword(s):  
Growth Rates ◽  
Tobacco Plant ◽  
Subsequent Development ◽  
Leaf Expansion ◽  
Flower Initiation ◽  
Relative Growth Rates ◽  
Leaf Surfaces ◽  
Number Of Leaves ◽  
Net Assimilation ◽  
Short Time

Detailed studies were made of the growth of tobacco plants during and after the experimental imposition of water stresses similar to those of commercial hardening and transplanting. During water stress (due to root damage, drought, or both) all growth rates were depressed, but, a short time after the relief of stress, relative leaf expansion rates, net assimilation rates, and relative growth rates rose to higher values than were reached by untreated plants at comparable stages of development. As a result, all stressed plants rapidly recovered from their period of adverse conditions. The plants that had originally been subjected to the most severe treatments overhauled those that had suffered less and finally acquired the greatest total leaf areas and dry weights. The increase was due to: (1) a change in the distribution of leaf surfaces, which occurred when leaf initiation was retarded relative to leaf expansion and resulted in increased growth of the lower leaves; (2) a delay in flower initiation, which took place at a higher node, increased the number of leaves, and prolonged the period of vegetative growth.

scholarly journals Specific Functions of Red, Far Red, and Blue Light in Flowering and Stem Extension of Long-day Plants

2001 ◽  
Vol 126 (3) ◽  
pp. 275-282 ◽  
Author(s):  
Erik S. Runkle ◽  
Royal D. Heins
Keyword(s):  
Blue Light ◽  
Flower Development ◽  
Red Light ◽  
Wide Band ◽  
Extension Growth ◽  
Photon Flux ◽  
Flower Initiation ◽  
Stem Extension ◽  
Long Day ◽  
Long Day Plants

For many long-day plants (LDP), adding far red light (FR, 700 to 800 nm) to red light (R, 600 to 700 nm) to extend the day or interrupt the night promotes extension growth and flowering. Blue light (B, 400 to 500 nm) independently inhibits extension growth, but its effect on flowering is not well described. Here, we determined how R-, FR-, or B-deficient (Rd, FRd, or Bd, respectively) photoperiods influenced stem extension and flowering in five LDP species: Campanula carpatica Jacq., Coreopsi ×grandiflora Hogg ex Sweet, Lobelia ×speciosa Sweet, Pisum sativum L., and Viola ×wittrockiana Gams. Plants were exposed to Rd, FRd, Bd, or normal (control) 16-hour photoperiods, each of which had a similar photosynthetic (400 to 700 nm) photon flux. Compared with that of the control, the Rd environment promoted extension growth in C. carpatica (by 65%), C. ×grandiflora (by 26%), P. sativum (by 23%), and V. ×wittrockiana (by 31%). The FRd environment suppressed extension growth in C. ×grandiflora (by 21%), P. sativum (by 17%), and V. ×wittrockiana (by 14%). Independent of the R: FR ratio, the Bd environment promoted stem extension (by 10% to 100%) in all species, but there was little or no effect on flowering percentage and time to flower. Extension growth was generally linearly related to the incident wide band (100 nm) R: FR ratio or estimated phytochrome photoequilibrium except when B light was specifically reduced. A high R: FR ratio (i.e., under the FRd filter) delayed flower initiation (but not development) in C. carpatica and C.×grandiflora and inhibited flower development (but not initiation) in V.×wittrockiana. Therefore, B light and the R: FR ratio independently regulate extension growth by varying magnitudes in LDP, and in some species, an FRd environment can suppress flower initiation or development.

scholarly journals Far-red and Blue Light Synergistically Mitigate Intumescence Injury of Tomato Plants Grown Under Ultraviolet-deficit Light Environment

HortScience ◽  
2016 ◽  
Vol 51 (6) ◽  
pp. 712-719 ◽  
Author(s):  
Tomomi Eguchi ◽  
Ricardo Hernández ◽  
Chieri Kubota
Keyword(s):  
Blue Light ◽  
Stem Elongation ◽  
Light Treatment ◽  
Light Environment ◽  
Photon Flux ◽  
Physiological Disorder ◽  
Tomato Plants ◽  
Light Emitting ◽  
Number Of Leaves ◽  
Percent Number

Intumescence injury is an abiotic-stress-induced physiological disorder associated with abnormal cell enlargement and cell division. The symptom includes blister- or callus-like growths on leaves, which occur on sensitive cultivars of tomato when they are grown under ultraviolet (UV)-deficit light environment, such as light-emitting diodes (LEDs). Previous studies suggest that intumescence can be reduced by increasing far-red (FR) or blue light. In the present study, effects of end-of-day FR (EOD-FR) light and high blue photon flux (PF) ratio during the photoperiod on intumescence injury were examined using ‘Beaufort’ interspecific tomato rootstock seedlings (Solanum lycopersicum × Solanum habrochaites), a cultivar highly susceptible to intumescence injury. Our study showed that EOD-FR light treatment moderately suppressed intumescence injury. Using EOD-FR light treatment, the percent number of leaves exhibiting intumescences was reduced from 62.0–70.7% to 39.4–43.1%. By combining high blue PF ratio (75%) during the photoperiod and EOD-FR light treatment, the percent number of leaves exhibiting intumescences was further suppressed to 5.0%. Furthermore, the combination of high blue PF ratio and EOD-FR light treatment inhibited undesirable stem elongation caused by EOD-FR light treatment. We found that high blue PF ratio during the photoperiod combined with a small dose of EOD-FR lighting (≈1 mmol·m−2·d−1 provided by 5.2 µmol·m−2·s−1 FR PF for 3.3 minutes) could inhibit the problematic intumescence injury of tomato plants grown under LEDs without negatively influencing growth or morphology.

scholarly journals Effects of HPS and LED lighting on cucumber leaf photosynthesis, light quality penetration and temperature in the canopy, plant morphology and yield

2017 ◽  
Vol 26 (2) ◽  
Author(s):  
Liisa Elina Särkkä ◽  
Kari Jokinen ◽  
Carl-Otto Ottosen ◽  
Timo Kaukoranta
Keyword(s):  
Light Quality ◽  
Stem Elongation ◽  
Plant Morphology ◽  
Light Level ◽  
Yield Potential ◽  
Flower Initiation ◽  
Initiation Rate ◽  
Led Lighting ◽  
Use Efficiency ◽  
Lower Temperature

In Nordic countries during the winter months supplemental lighting is essential for year-round cucumber production. In this research the effects of full HPS (top and interlights) illumination is compared to hybrid (HPS top, LED interlights) and full LED (top and interlights). The results showed that fruit yield was highest in the HPS-LED treatment whereas the electrical use efficiency (kg yield J-1) increased when HPS was replaced with LED. In LED-LED the light use efficiency (g fruit FW mol-1 PAR) was highest but resulted in a fewer number of fruits in mid-winter particularly and the lowest yield potential. The lower temperature and lower light level due to LED-LED lighting lead to reduced photosynthesis capacity, flower initiation rate and water use efficiency whereas increased stem elongation and leaf expansion compared to other treatments. Differences in light quality of LED and HPS are also discussed in terms of cucumber yield formation.

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