LED light for in vitro and ex vitro efficient growth of economically important highbush blueberry (<Emphasis Type="Italic">Vaccinium corymbosum</Emphasis> L.)

Light-emitting diodes (LEDs) are useful for the growth of many plants, but not known for blueberry species. This study examined the effects of fluorescent lamps and 100 % red, 80 % red plus 20 % blue, 50 % red plus 50 % blue, and 100 % blue LEDs on the growth and development of highbush blueberry shoots under aseptic and non-aseptic conditions. Results revealed that monochromatic blue LEDs accumulated the highest contents of leaf chlorophylls. In contrast, monochromatic red LEDs inhibited chlorophyll accumulation, but produced the longest shoots and roots and provided high percentages of side shoot formation from ex vitro plants. Mixed LEDs, particularly 50 % red plus 50 % blue light, improved plant growth with respect to notably increased shoot and root biomass. Direct rooting of in vitro shoots under non-aseptic conditions was readily achieved using a commercial mixture of perlite and peat moss with high humidity controls. These findings obviously suggest the efficient use of LEDs to replace traditional fluorescent lamps in large-scale propagation of the highbush blueberry, and also pave the way for future studies on LEDs for standardizing micropropagation protocols to shrub crops and woody plants.     

Combination of Red and Blue Lights Improved the Growth and Development of Eggplant (Solanum melongena L.) Seedlings by Regulating Photosynthesis

The photosynthesis, photomorphogenesis, and photoperiod processes in plants are regulated according to light intensity and quality. The aim of this study was to investigate the effects of different light qualities on eggplant seedlings and determine the best light quality for growth. The seedlings of eggplant cultivar ‘Jingqiejingang’ were grown under light-emitting diodes (LEDs): white (W, the control), red (R), blue (B), and different ratios of B/R lights (B/R = 1/1, B/R = 1/3, B/R = 1/6, B/R = 1/9). The growth parameters, leaf morphology, photosynthetic performance, chlorophyll fluorescence, and the carbon and nitrogen metabolism in the leaves of eggplant seedlings under different LED light treatments were studied. The results showed that the plant height, leaf development, and photosynthetic characteristics were inhibited by red light but elevated by blue light compared with the control. Conversely, the contents of chlorophyll a, chlorophyll b, and carotenoids were all increased by red light, while decreased by blue light significantly. In addition, the contents of carbohydrates and the activities of nitrogen assimilation enzymes were not or little changed by the monochromatic blue and red light. The combined light of red and blue were more beneficial for growth than the monochromatic light, especially B/R = 1/3 light. Under B/R = 1/3 light, the parameter values of plant growth, leaf development, photosynthetic pigments and characteristics, and carbon and nitrogen metabolism were all maximum. Taken together, combined application lights of red and blue are good practice for the cultivation of eggplant seedlings, and LED B/R = 1/3 light was optimum.

     

Green light drives photosynthesis in mosses

Temperate forests are characterised by variable light quality (i.e. spectral composition of light) at or near the forest floor. These understory environments have a high concentration of green light, as red and blue light are preferentially absorbed by upper canopy leaves. Understory species may be well-adapted for using green light to drive photosynthesis. Angiosperms have been shown to use green light for photosynthesis, but this ability has not been demonstrated in shade-dwelling bryophytes. In this study, net photosynthetic rate (P_N) of three temperate understory species of moss (Dichodontium pellucidum (Hedw.) Schimp., Leucobryum albidum (Brid. ex P.Beauv) Lindb. and Amblystegium serpens (Hedw.) Schimp.) was measured under green, red?+?blue, and red?+?blue?+?green light to assess green light use efficiency. All three species were capable of photosynthesising beyond their respiratory demands using solely green light, with higher green light use efficiency measured in plants collected from areas with greater canopy cover, suggesting growth in a green light concentrated environment increases green light use efficiency. Each species was also collected from sites differing in their degree of canopy cover and grown under three light treatments (high light, low light, and green light). Photosynthetic efficiency (chlorophyll fluorescence), tissue nitrogen and carbon isotope concentrations were assessed after a short growth period. Growth conditions had little effect on leaf chemistry and monochromatic green light did not significantly degrade photosynthetic efficiency. This study provides the first evidence to date of positive net ‘green light photosynthesis’ in mosses.     

Effect of light on the formation of atypical fruiting structures inGanoderma lucidum

Ganoderma lucidum develops atypical fruiting structures (AFSs) with non-basidiocarpous basidiospores during the incubation under light on nutrient agar media. To examine the light quality effective in inducing AFSs, 17 isolates ofG. lucidum were incubated on agar media under light from different colored fluorescent lamps. Of the 17 isolates, 13 isolates produced AFSs and basidiospores under fluorescent lamps. Nine isolates formed AFSs in a broad light region from P-B (pure blue) to P-R (pure red) lamps. The remaining 4 isolates produced AFSs under different colored fluorescent lamps. No isolates formed AFSs in the dark or under BLB (black light blue) illumination. The mycelial growth was inhibited by light illumination, especially BLB light. Although the AFSs were induced at a very low light intensity such as 0.5µmol m^–2s^–1, the optimum light intensity for the AFS formation varied depending on the kind of fluorescent lamp and the isolate. The AFS formation inG. lucidum isolates was also tested under monochromatic light produced by the combination of interference filters and colored glass filters.G. lucidum isolates were separable into various types in the responses of AFS formation to monochromatic light, indicating thatG. lucidum is heterogeneous in its photo-response with regard to AFS formation.     

Effects of light quality on the chloroplastic ultrastructure and photosynthetic characteristics of cucumber seedlings

To understand how light quality influences plant photosynthesis, we investigated chloroplastic ultrastructure, chlorophyll fluorescence and photosynthetic parameters, Rubisco and chlorophyll content and photosynthesis-related genes expression in cucumber seedlings exposed to different light qualities: white, red, blue, yellow and green lights with the same photosynthetic photon flux density of 100 μmol m^?2 s^?1. The results revealed that plant growth, CO₂ assimilation rate and chlorophyll content were significantly reduced in the seedlings grown under red, blue, yellow and green lights as compared with those grown under white light, but each monochromatic light played its special role in regulating plant morphogenesis and photosynthesis. Seedling leaves were thickened and slightly curled; Rubisco biosynthesis, expression of the rca, rbcS and rbcL, the maximal photochemical efficiency of PSII (Fv/Fm) and quantum yield of PSII electron transport (Ф_PSII) were all increased in seedlings grown under blue light as compared with those grown under white light. Furthermore, the photosynthetic rate of seedlings grown under blue light was significantly increased, and leaf number and chlorophyll content of seedlings grown under red light were increased as compared with those exposed to other monochromatic lights. On the contrary, the seedlings grown under yellow and green lights were dwarf with the new leaves etiolated. Moreover, photosynthesis, Rubisco biosynthesis and relative gene expression were greatly decreased in seedlings grown under yellow and green light, but chloroplast structural features were less influenced. Interestingly, the Fv/Fm, Ф_PSII value and chlorophyll content of the seedlings grown under green light were much higher than those grown under yellow light.     

The effect of metal chelators on the production of hydroxyl radicals in thylakoids

From the algal genus Ostrobium two species are known which express a chlorophyll antenna absorbing between 710 and 725 nm to a different extent. In a comparative study with these two species it is shown that quanta absorbed by this long wavelength antenna can be transferred to PS II leading to significant PS␣II-related electron transfer. It is documented that under monochromatic far red light illumination growth continues with rather high efficiency. The data show that the uphill-energy transfer to PS II reduces the quantum yield under white light significantly. It is discussed that this strategy of energy conversion might play a role in special environments where far red light is the predominant energy source.     

Measurement of gradients of absorbed light in spinach leaves from chlorophyll fluorescence profiles

Profiles of chlorophyll fluorescence were measured in spinach leaves irradiated with monochromatic light. The characteristics of the profiles within the mesophyll were determined by the optical properties of the leaf tissue and the spectral quality of the actinic light. When leaves were infiltrated with 10^?4M DCMU [3‐(3,4‐dichlorophenyl)‐1, 1‐dimethyl‐urea] or water, treatments that minimized light scattering, irradiation with 2000 μmol m^?2 s^?1 green light produced broad Gaussian‐shaped fluorescence profiles that spanned most of the mesophyll. Profiles for chlorophyll fluorescence in the red (680 ± 16 nm) and far red (λ > 710 nm) were similar except that there was elevated red fluorescence near the adaxial leaf surface relative to far red fluorescence. Fluorescence profiles were narrower in non‐infiltrated leaf samples where light scattering increased the light gradient. The fluorescence profile was broader when the leaf was irradiated on its adaxial versus abaxial surface due to the contrasting optical properties of the palisade and spongy mesophyll. Irradiation with blue, red and green monochromatic light produced profiles that peaked 50, 100 and 150 μm, respectively, beneath the irradiated surface. These results are consistent with previous measurements of the light gradient in spinach and they agree qualitatively with measurements of carbon fixation under monochromatic blue, red and green light. These results suggest that chlorophyll fluorescence profiles may be used to estimate the distribution of quanta that are absorbed within the leaf for photosynthesis.     

Light scattering,chlorophyll fluorescence and state of the adenylate system in illuminated spinach leaves

Scattering of green light and chlorophyll fluorescence by spinach leaves kept in a stream of air or nitrogen were compared with leaf adenylate levels during illumination with blue, red or far-red light. Energy charge and ATP-ADP ratios exhibited considerable variability in different leaves both in the dark and in the light. Variability is explained by different possible states of the reaction oxidizing triose phosphate or reducing 3-phosphoglycerate. Except when oxygen levels were low, there was an inverse relationship between light scattering and chlorophyll fluorescence during illumination with blue or red light. When CO₂ was added to a stream of CO₂-free air, chlorophyll fluorescence increased, sometimes after a transient decrease, and both light scattering and leaf $\text{ATP}\text{ADP}$ ratios decreased. Similar observations were made when air was replaced by nitrogen under blue or high-intensity red light. Under these conditions, over-reduction caused inhibition of electron transport and phosphorylation in chloroplasts. However, when air was replaced by nitrogen during illumination with low-intensity red light or far-red light, light scattering increased instead of decreasing. Under these light conditions, $\text{ATP}\text{ADP}$ ratios were maintained in the light. They decreased drastically only after darkening. Although $\text{ATP}\text{ADP}$ ratios responded faster than light scattering or the slow secondary decline of chlorophyll fluorescence due to illumination, it appeared that in the steady state, light scattering and chlorophyll fluorescence are useful indicators of the phosphorylation state of the leaf adenylate system at least under aerobic conditions, when chloroplast and extrachloroplast adenylate systems can effectively communicate.     

Photophysiology of turion formation and germination inSpirodela polyrhiza

Standardized laboratory techniques for the vegetative growth of the duckweedSpirodela polyrhiza (Lemnaceaé), and for formation as well as germination of their turions were described. Increasing photon fluence rates of blue or red light increased the yield of turions. A specific stimulating effect of blue light was demonstrated under autotrophic but not under mixotrophic conditions. Therefore the spectral composition of light is not important in mixotrophic formation of turions whereas in autotrophic formation light sources with a higher portion of blue light are recommended. Dark-grown (etiolated) turions showed accelerated germination and higher germination percentage in comparison with light-grown turions after induction by a single red light pulse. This difference was overcome in continuous red light by speeding up the germination response of light-grown turions. Use of Petri dishes (8 cm³ nutrient solution) instead of Erlenmeyer flasks (50 cm³ nutrient solution) retarded germination response. Especially for long term experiments the use of Erlenmeyer flasks is recommended. Storage of turions for 72 h at 25 ‡C following at 5 ‡C in darkness after-ripening resulted in a decreased lag phase of the light-induced germination both after induction by a single light pulse and in continuous light. We thank Dr. Halina Gabrys, University of Crakow, Poland for critical discussion.     

不同LED光源对乌塌菜生长、光合特性及营养品质的影响

与传统光源相比,LED具有光谱可控、亮度高但发热量小、寿命长等优势.LED光源可实现光谱可控,通过调制光谱与植物的感光细胞最优结合来影响植物的生长发育与营养品质.本研究利用LED精量调制光源,以‘菊花小八叶’乌塌菜品种为试验材料,设红光、蓝光、红/蓝光(3/1)、红/蓝光(7/1)、白/红/蓝光(3/2/1)5个处理,以白光为对照,研究不同光质对乌塌菜生长、光合特性及品质的影响.结果表明： 红光有利于乌塌菜生物量和茎粗的增大,而蓝光有抑制作用;叶绿素含量以红/蓝光(7/1)处理最高,且叶绿素总量与红/蓝光比值呈正相关,虽然蓝光显著降低叶绿素含量,但提高了叶绿素 a/b 值;光合速率和蒸腾速率均以红光处理最高,与对照相比分别增加43.8%和55.1%,而蓝光处理下有较高的气孔导度及胞间CO₂浓度.不同光质处理对乌塌菜的荧光参数有较大影响,白光的F_v/F_m、F_v/F_o和Φ_PSⅡ均最大;红光可以提高可溶性糖含量,蓝光能提高可溶性蛋白含量,白光能增加维生素C含量.综合分析,红/蓝光(7/1)处理在增加叶片光合色素含量,提高光合速率,促进植株生长和改善营养品质方面为最优组合.     

Changes in Plastidic and Cytoplasmic Pyruvate Kinase Activity during Chloroplast Development of Pea in Blue and Red Light

Pyruvate kinase (PK) activity was demonstrated in the cytosolas well as in the plastids of pea leaves. Etioplasts and chloroplastscontained about 12% of the total activity. The presence of PKactivity in different cellular compartments and the pronounceddifferences in kinetic and regulatory properties indicate thatthese activities are due to isoenzymes. When etiolated pea leaves were illuminated with weak blue light,the plastidic PK activity increased immediately, reaching amaximum (about 21% of the total activity) after 24 h of illumination.Under red light, there was a lag period of about 4 h beforethe increase in isoenzyme activity. After 24 h of illumination,however, it reached the maximum found with blue light. In contrast,light quality had no appreciable effect on cytoplasmic PK andphosphoenolpyruvate carboxylase. Increases in NADP-dependent glyceraldehyde 3-phosphate dehydrogenaseactivity and in the soluble protein in the plastids were somewhathigher, whereas the increase in chlorophyll content was slightlylower under blue light than under red light. Blue light specificallyincreased the chlorophyll alb-ratio. These different responsesto the light quality during chloroplast development indicatethat more than one photoreceptor is involved in these processes. The results obtained for pea PK also are discussed in comparisonwith similar findings for the chlorophyll-free Chlorella mutantno. 20. (Received January 19, 1982; Accepted April 21, 1983)     

Phototropism and polarotropism of primary chloronemata of the moss Physcomitrella patens: responses of the wild-type

Primary chloronemata growing from germinated spores of the moss Physcomitrella patens adopt one of two preferred polarotropic orientations depending on the wavelength and photon fluence rate of monochromatic light. Growth is mainly parallel to the electrical vector of plane polarised light in blue light and higher fluence rates of red light, and perpendicular to the electrical vector in the green and far-red regions of the spectrum and in low fluence rates of red light. The transition between the two polarotropic orientations, at wavelengths where it can be observed, usually occurs over a narrow range of fluence rates, and at this point the filaments do not grow randomly but tend to adopt in approximately equal numbers one of the preferred directions of growth. The primary chloronemata are positively phototropic in far-red light and in red light of low fluence rates, but tend to grow at right angles to the incident light in high fluence rates of red light. Simultaneous illumination with a high fluence rate of red light and a low fluence rate of far-red light causes a marked increase in the percentage of filaments growing towards the red light source at the expense of those growing at right angles to it, supporting the hypothesis that in red and far-red light, at least, the responses are controlled by the photoequilibrium of a phytochrome pool.     

The impact of monochromatic blue and red LED light upon performance of photo microbial fuel cells (PMFCs) using Chlamydomonas reinhardtii transformation F5 as biocatalyst

Photosynthetic microbial fuel cells (PMFCs) are devices that convert chemical energy into the form of electricity through the catalytic activity of photosynthetic microorganisms. Power densities produced by the photosynthetic microalgae are greatly dependant on light sources and light intensities because these two factors can affect the chlorophyll formation, photosynthesis processes and stomata opening in the microalgae cells. In the present study, Chlamydomonas reinhardtii transformation F5 was used as biocatalyst in photo microbial fuel cells (PMFCs) and were illuminated with monochromatic blue and red LED lights at various light intensities (100, 300, 600 and 900 lx), respectively. The kinetic analysis was successfully employed to describe the intracellular and extracellular electron transfer mechanism of the cells. The results demonstrate that the performance of PMFCs increased in terms of maximum power density and exchange current density (i_o) with the tendency of decreasing in internal resistance (R_int) and over potential (η) values as increasing monochromatic blue and red LED light intensities. However the PMFCs performed better under red LED light as compared to operating under blue LED light. The maximum power density can reach 12.947 mW m⁻², which could be a potential micro-power supply.     

Modified light spectral conditions prior to cryopreservation alter growth characteristics and cryopreservation success of potato (<Emphasis Type="Italic">Solanum tuberosum</Emphasis> L.) shoot tips in vitro

Light is one of the most important factors affecting growth and morphogenesis of plants. Light intensity, photoperiod and spectral composition greatly affect morphogenetic responses of in vitro plants. Modification of light spectra during recovery after cryopreservation improves survival and regeneration, but the effect of modified light conditions prior to cryopreservation are not known. Therefore, the aim of the present study was to follow the photomorphogenetic response of potato plants (Solanum tuberosum L.) under different light qualities i.e. cool white fluorescent (CW) used as control, warm white (HQI), white LEDs (W), blue LEDs (B), red LEDs (R) and a combination of red with 10?% of blue LEDs (RB) prior to cryopreservation, affecting recovery of cultivars Agrie Dzeltenie, Bintje, Maret, Anti and Désirée in vitro. Light spectral quality had a significant effect on growth characteristics of potato plants in vitro. Red light (R) promoted elongation growth but biomass accumulation remained low under monochromatic light treatments. Some of the pre-cryopreservation light treatments significantly affected post-cryopreservation success. Under blue LEDs, high early recovery was observed for all cultivars tested, whereas under red (R) or (HQI), lowest survival percentages were obtained 2–4 weeks after thawing. Specifically, during early recovery, blue light increased survival from 26 to 66?%, 4 to 31?% and 16 to 48?% for cultivars Agrie Dzeltenie, Anti, and Désirée, compared to illumination by red LEDs. Therefore, light spectral quality prior to cryopreservation can significantly affect the cryopreservation success of potato shoot tips.     

Growth and cell cycle of Ulva compressa (Ulvophyceae) under LED illumination

The cell‐cycle progression of Ulva compressa is diurnally gated at the G₁ phase in accordance with light–dark cycles. The present study was designed to examine the spectral sensitivity of the G₁ gating system. When blue, red, and green light‐emitting diodes (LEDs) were used for illumination either alone or in combination, the cells divided under all illumination conditions, suggesting that all colors of light were able to open the G₁ gate. Although blue light was most effective to open the G₁ gate, red light alone or green light alone was also able to open the G₁ gate even at irradiance levels lower than the light compensation point of each color. Occurrence of a period of no cell division in the course of a day suggested that the G₁ gating system normally functioned as under ordinary illumination by cool‐white fluorescent lamps. The rise of the proportion of blue light to green light resulted in increased growth rate. On the other hand, the growth rates did not vary regardless of the proportion of blue light to red light. These results indicate that the difference in growth rate due to light color resulted from the difference in photosynthetic efficiency of the colors of light. However, the growth rates significantly decreased under conditions without blue light. This result suggests that blue light mediates cell elongation and because the spectral sensitivity of the cell elongation regulating system was different from that of the G₁ gating system, distinct photoreceptors are likely to mediate the two systems.     

Effect of Various Light Treatments on Chlorophyll Formation in Excised Potato Roots

Potato root tips were grown in cultures and the effect of blue, red, and white light on chlorophyll formation was studied. The roots grown in white light turned green in 4–6 weeks, whereas in blue or red light, green colour occasionally appeared at places. The chlorophyll contents, as determined by the spectrophotometeric method, were found to be maximum in unfiltered light followed by blue and red light. In white and blue light treatments chlorophyll a contents were higher than chlorophyll b, however in red light this was reversed. The results are compared with earlier experiments on chlorophyll formation in excised roots.     

Two-step mechanism of photodamage to photosystem II: step 1 occurs at the oxygen-evolving complex and step 2 occurs at the photochemical reaction center

Under strong light, photosystem II (PSII) of oxygenic photosynthetic organisms is inactivated, and this phenomenon is called photoinhibition. In a widely accepted model, photoinhibition is induced by excess light energy, which is absorbed by chlorophyll but not utilized in photosynthesis. Using monochromatic light from the Okazaki Large Spectrograph and thylakoid membranes from Thermosynechococcus elongatus, we observed that UV and blue light inactivated the oxygen-evolving complex much faster than the photochemical reaction center of PSII. These observations suggested that the light-induced damage was associated with a UV- and blue light-absorbing center in the oxygen-evolving complex of PSII. The action spectrum of the primary event in photodamage to PSII revealed the strong effects of UV and blue light and differed considerably from the absorption spectra of chlorophyll and thylakoid membranes. By contrast to the photoinduced inactivation of the oxygen-evolving complex in untreated thylakoid membranes, red light efficiently induced inactivation of the PSII reaction center in Tris-treated thylakoid membranes, and the action spectrum resembled the absorption spectrum of chlorophyll. Our observations suggest that photodamage to PSII occurs in two steps. Step 1 is the light-induced inactivation of the oxygen-evolving complex. Step 2, occurring after step 1 is complete, is the inactivation of the PSII reaction center by light absorbed by chlorophyll. We confirmed our model by illumination of untreated thylakoid membranes with blue and UV light, which inactivated the oxygen-evolving complex, and then with red light, which inactivated the photochemical reaction center.     

不同LED光质对金线莲生长的影响

以福建产金线莲（Anoectochilus roxburghii）为材料,研究不同LED光质（红光、黄光、蓝光）对金线莲生长指标以及叶绿素、气孔的影响。结果表明,红光与黄光有利于金线莲株高增长,与对照相比分别提高18.74%、21.47%,但二者处理的植株较为瘦弱,且红光和黄光处理下的植株叶绿素a和叶绿素b含量较低。蓝光处理下金线莲生长情况较好,叶面积与对照相比增长明显,且叶绿素含量相对较高。不同LED光质处理下的植株气孔频度、长度、宽度与对照相比都有一定增长。     

荧光粉激发型LED光对拟南芥生长发育的影响

在室内人工光源照射条件下, 探究150 μmol∙m^-2·s^-1光强下不同比例的红蓝光对拟南芥(Arabidopsis thaliana)生长发育的影响。以哥伦比亚(Columbia-0)野生型拟南芥为研究对象, 采用荧光粉激发型LED作为植物生长光源, 以SrSiAlN₃为红色基底, 调节荧光粉添加量获得不同红蓝光谱, 考察不同光照条件下拟南芥萌发率、根长、株高、叶绿素含量和相对电导率等参数的变化规律。结果表明, 在荧光粉激发型LED光照调节下的拟南芥具有更高的萌发率、根长、株高、叶绿素含量和相对电导率, 且在红蓝光质比为2:1时萌发率(95.63%)和叶绿素含量(26.7)最高; 在红蓝光质比为4:5时根长(4.19 cm)较长; 在红蓝光质比为4:1时株高(15.5 cm)较高; 在红蓝光质比为4:5时相对电导率(40.5 S·m^-1)较大。研究结果表明相对平衡的光质(红蓝光质比为4:1)有利于拟南芥生长发育, 且减少蓝光比例对根系生长及叶绿素积累有一定的促进作用。研究表明不同光谱对模式植物拟南芥的生长发育有较明显的影响, 改变光谱组成可以对植物的生长发育起不同程度的调控作用。     

Assembly of LH2 light-harvesting complexes in Rhodopseudomonas palustris cells illuminated by blue and red light

We investigated the formation of the B800-850 complex in cells of the bacterium Rhodopseudomonas palustris AB illuminated by red and blue light under anaerobic growth conditions. Under red illumination, the B800-850 complex was assembled with a reduced absorption band at 850 nm. The results of re-electrophoresis of the B800-850 complex and oxidation in the presence of potassium iridate suggest its heterogeneity. It may be a mixture of two complexes (B800 and B800-850). The B800-850 complex lacks the capacity for conformational transitions if assembled under blue illumination. Accordingly, the light-harvesting complex assembled in the blue light contains polypeptides that are not synthesized under normal conditions or at increased or decreased light intensities. The mechanism of regulation of the synthesis of the polypeptides of light-harvesting B800-850 complex and its dependence on the spectral composition of the light is discussed.