Profiles of photosynthetic pigment accumulation and expression of photosynthesis-related genes in the marine cyanobacteria Synechococcus sp.: Effects of LED wavelengths

Light quality is a significant environmental factor that influences photosynthetic pigments in cyanobacteria. In the present study, we illuminated the marine cyanobacteria Synechococcus sp. with white (350 ～ 700 nm), red (630 nm), green (530 nm), and blue (450 nm) light emitting diodes (LEDs) and measured pigment levels (chlorophyll, carotenoid, and phycobiliprotein) and expression of photosynthesis-related genes (pebA, psbB, and psaE). The amount of photosynthetic pigments (total pigments, chlorophyll, and phycobiliproteins) was higher in the green and blue LED groups than in the white and red LED groups after 8 days of culture. The cells were prepared in a 1.5 mL solution for the analysis of the total pigments, chlorophyll, and carotenoid, and in a 2 mL for analysis of phycobiliproteins. The mRNA expression levels of pebA and psbB significantly increased after 8 days of cultivation under green and blue light, while the mRNA expression levels of psaE decreased. These results indicate that green and blue light increase the accumulation of photosynthetic pigments. In contrast red light induced mRNA expression of psaE and stimulated cell growth in Synechococcus sp.     

Effect of Colored Light on Stomatal Opening Rates of Vicia faba L

The average opening rate of Vicia faba L. stomata was determined over an initial 20-minute light period following darkness. Nonsaturating intensities of broad band red and blue light had similar quantum effectiveness for the promotion of opening, whereas broad band green was about 40% and far red about 5% as effective. The opening rates under saturating red, green, and blue light were the same. Net photosynthesis was measured under various intensities of the same red, green, and blue light spectra. Red and blue light were equally efficient in causing photosynthesis, whereas green was 60% as effective. The light compensation points for the three colors were at higher intensities than those which saturated the opening rate response. These data suggest that only a single pigment system, probably the photosynthetic pigments, is responsible for initiating the light-induced opening response in V. faba stomata.     

Chromatic adaptation in lichen phyco- and photobionts

The effect of light quality on the photosynthetic pigments as chromatic adaptation in 8 species of lichens were examined. The chlorophylls, carotenoids in 5 species with green algae as phycobionts (Cladonia mitis, Hypogymnia physodes, H. tubulosa var. tubulosa and subtilis, Flavoparmelia caperata, Xanthoria parietina) and the chlorophyll a, carotenoids and phycobiliprotein pigments in 3 species with cyanobacteria as photobionts (Peltigera canina, P. polydactyla, P. rufescens) were determined. The total content of photosynthetic pigments was calculated according to the formule and particular pigments were determined by means CC, TLC, HPLC and IEC chromatography. The total content of the photosynthetic pigments (chlorophylls, carotenoids) in the thalli was highest in red light (genus Peltigera), yellow light (Xanthoria parietina), green light (Cladonia mitis) and at blue light (Flavoparmelia caperata and both species of Hypogymnia). The biggest content of the biliprotein pigments at red and blue lights was observed. The concentration of C-phycocyanin increased at red light, whereas C-phycoerythrin at green light.     

不产氧光合细菌光合色素的光氧调控机制

[目的]为不产氧光合细菌光合色素研究提供可行的较系统规范的研究方法和数据,揭示固氮红细菌(Rhodobacter azotoformans 134K20)光合色素光氧适应性机制.[方法]采用光谱法和色谱法对光和氧调控下的类胡萝卜素和细菌叶绿素合成代谢进行了研究.[结果]134K20菌株光照好氧时细胞得率最高.光照厌氧时主要合成3黄、1红、1紫、2绿、2蓝9种色素,黄色素大量表达.有氧时红色素大量表达,且启动2种新的红色素和1种新的紫色素表达,而黄色和蓝绿色素则受氧抑制.黑暗好氧主要合成2黄、3红、2紫、1绿、1蓝9种色素,但不同于光照厌氧.光照好氧时黄色素减少到1种,紫色素含量增加,其余同黑暗好氧.[结论]固氮红细菌(Rhodobacter azotoformans 134K20)是通过PpsR调节途径来调节光合基因表达的.黄色和红色素属于类胡萝卜素.黄色素1属于球形烯系列,其余两种黄色素是新的类胡萝卜素组分.红色素为新的球形烯酮组分,3种红色素极性、峰形和峰位差别显著,正己烷能显示其精细结构.紫色为极性较大的细菌脱镁叶绿素,绿色和蓝色为4种极性不同的细菌叶绿素a中间产物.乙醚甲醇法适合类胡萝卜素的提取,丙酮甲醇冰冻研磨法能快速有效完全提取光合色素.溶剂效应可有效鉴别细菌叶绿素a中间产物.     

Light-induced efficiency and pigment alterations in red algae

The low photosynthetic efficiency of chlorophyll in freshly collected red algae, can, in the case of Porphyra perforata, P. nereocystis, and Porphyridium cruentum, be increased by growing the algae for 10 days in red or blue light. Exposure to darkness or to green light maintains the algae in their originally low efficiency with respect to chlorophyll, while retaining the high efficiency of phycobilins. Red- or blue-adapted algae are rapidly reversed by exposure to green light, the chlorophyll efficiency dropping to low values again in a few hours. This is assumed to account for the action spectrum of freshly gathered plants. Some pigment changes were observed, but not in the direction of "chromatic adaptation;" and the carotenoid pigments were not activated, even by blue light, but remained as photosynthetically inactive shading filters. The higher red algae (Florideae) did not show activation of chlorophyll by red or blue light.     

Effects of Chromatic Adaptation on the Photochemical Apparatus of Photosynthesis in Porphyridium cruentum

Cells of Porphyridium cruentum were grown in different colors of light which would be absorbed primarily by chlorophyll (Chl) (red and blue light) or by the phycobilisomes (green or two intensities of cool-white fluorescent light), and samples of these cells were frozen to −196 C for measurements of absorption and fluorescence emission spectra. Cells grown in the high intensity white light had least of all of the photosynthetic pigments, a higher ratio of carotenoid/Chl, but essentially the same ratio of phycobilin to Chl as cells grown in the low intensity white light. The ratio of photosystem II (PSII) to photosystem I (PSI) pigments was affected by light quality; the ratios of phycobilin to Chl and of short wavelength (PSII) Chl to long wavelength (PSI) Chl were both greater in the cells grown in red or blue light.     

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.     

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.     

Adaptation of the Photosynthetic Apparatus of Chlorella and Ankistrodesmus to Blue and Red Light

The mode of adaptation of the photosynthetic apparatus of three unicellular green algae, Ankistrodesmus braunii, Chlorella fusca and Chlorella saccharophila to red and blue light are documented by the fluence-rate curves of photosynthetic oxygen evolution. For all three algae tested photosynthetic capacity, respiration and light compensation point were higher for cells grown under red light, while the chlorophyll content increased in blue light-grown cells. Blue light-adapted cells have a lower chlorophyll a to chlorophyll b ratio and more chlorophyll in the light-harvesting system than red light-adapted cells, as shown in the electrophoretic profile of the pigment-protein complexes. It is concluded that the action of red light resembles that of high levels of white light, while blue light causes the same effects as low levels of white light. In agreement with previous publications these findings indicate that the mode of adaptation to different light qualities is ubiquitous in unicellular green algae.     

Effects of light quality on the circadian rhythm of leaf movement of a short-day-plant

Studies were made of the effects of blue, green, red and far-red (FR) light on the circadian rhythm of leaf movement of Coleus blumei × C. frederici, a short day plant. Under continuous illumination with blue light, there was a significant lengthening of the period of the rhythm to about 24.0 hr, as compared to 22.5 hr in continuous darkness. Under continuous red light, the period length was significantly shortened to 20.5 hr. Under continuous green or FR, the period length was not significantly different from the dark control. It was observed that under continuous FR illumination, the leaves tended to oscillate in a more downward position. Eight-hr red light signals were effective in advancing the phase of the rhythm as compared to a control under continuous green light. Blue light signals were effective in delaying the phase of the rhythm. FR light signals were ineffective in producing either delay or advance phase shifts. Far-red light did not reverse the effects of either red or blue light signals. On the basis of these results it is suggested, that pigments which absorb blue or red light, rather than phytochrome, mediate the effect of light on the circadian rhythm of leaf movement.     

Flowering of Cultivated Green and SAN 9789-Treated Chenopodium rubrum Plants Exposed to White,Blue, and Red Light

Green plants and plants devoid of photosynthetic pigments were compared with regard to their ability to flower under various growth conditions. Green plants of Chenopodium rubrum L. and plants treated with norflurazon SANDOZ-9789 (SAN) were grown on sucrose-containing media with or without hormones (GA₃, BA, IAA, ABA) under short-day photoperiodic or continuous illumination with white, blue, or red light. Green and SAN-treated albino plants produced flowers only under short-day conditions. The flowering of green plants was independent of the presence of sucrose and hormones in the medium as well as of the light quality. The albino plants produced flowers under white and blue light but did not flower in red light. The addition of GA₃ or BA to the medium induced flowering of albino plants exposed to red light. The functional interaction of photoreceptors in the flowering control is discussed.     

Analyzing photosynthetic activity and growth of Solanum lycopersicum seedlings exposed to different light qualities

To investigate how light quality influences tomato (Solanum lycopersicum L) seedlings, we examined changes in plant growth, chloroplast ultrastructure, photosynthetic parameters and some photosynthesis-related genes expression levels. For this, tomato plants were grown under different light qualities with the same photosynthetic photon flux density: red (R), blue (B), yellow (Y), green (G) and white (W) lights. Our results revealed that, compared with plants grown under W light, the growth of plants grown under monochromatic lights was inhibited with the growth reduction being more significant in the plants grown under Y and G lights. However, the monochromatic lights had their own effects on the growth and photosynthetic function of tomato seedlings. The plant height was reduced under blue light, but expression of rbcS, rbcL, psbA, psbB genes was up-regulated, and the ΦPSII and electron transport rate (ETR) values were enhanced. More starch grains were accumulated in chloroplasts. The root elongation, net photosynthetic rate (Pn), NPQ and rbcS and psbA genes expression were promoted under red light. Yellow light- and green light-illuminated plants grew badly with their lower Rubisco content and Pn value observed, and less starch grains accumulated in chloroplast. However, less influence was noted of light quality on chloroplast structure. Compared with yellow light, the values of ΦPSII, ETR, qP and NPQ of plants exposed to green light were significantly increased, suggesting that green light was beneficial to both the development of photosynthetic apparatus to some extent.     

Photosynthetic Performance and Pigment Composition of Leaves from two Tropical Species is Determined by Light Quality

Abstract: A suitable light quantity and quality is essential for optimal photosynthetic metabolism. Using combinations of three lamp types, the impact of the quality of artificial light conditions on the photosynthetic apparatus of leaves developed in growth chambers was analysed. The VIALOX‐Planta lamps are quite poor outside the green to orange (520 ‐ 620 nm) wavelength range, while the HQI‐BT lamps present a more uniform spectral intensity between 425 and 650 nm (blue to red). The halogen lamps are particularly rich in the red and far red range of the electromagnetic spectra. The lamps also differ in the red: far red ratio, which were 3.07 (VIALOX), 2.06 (HQI‐BT) and 1.12 (halogen). Clear positive effects were detected in most of the photosynthetic parameters in relation to light quality, both at stomatal and mesophyll levels. Despite some species‐dependent sensitivity to blue and red/far red wavelengths, observed among the studied parameters, the best photosynthetic performances of the test plants (Packyrhizus ahipa and Piatã, a hybrid of Coffea dewevrei×Coffea arabica) were obtained almost always with the reinforcement of blue (HQI‐BT lamps), red and far red (halogen lamps) wavelengths and with a red: far red ratio closer to that observed in nature. This suggests the involvement of more than one photoreceptor family in photosynthetic performance. Under such light conditions, increases in net photosynthesis and stomatal conductance were observed and, despite the moderate effects on photosynthetic capacity, strong effects were observed in the capture and transfer of light energy in the antennae pigments, photochemical efficiency of photosystem II and electron transport. This was related to the striking quantitative and qualitative impacts observed on total chlorophylls and carotenoids, which reached, in some cases, increases of 100 and 200 %, respectively. Among carotenoids, increases as high as 9‐fold for α‐carotene were observed (P. ahipa), with chlorophyll (a/b), total (chlorophyll/carotenoid) and carotene (α/β) ratios also strongly affected. This would have affected the structure and stability of photosynthetic membranes which, in turn, affected photosynthetic‐related processes (e.g., antennae pigments, photosystem II and electron transport efficiencies). This was particularly clear in the HQI + halogen treatment. The results unequivocally show that light quality could remain a clear limiting factor for leaf/plant development under artificial light conditions, which could be overcome using more than one lamp type, with complementary emission spectra.     

Blue light reduces photosynthetic efficiency of cyanobacteria through an imbalance between photosystems I and II

Several studies have described that cyanobacteria use blue light less efficiently for photosynthesis than most eukaryotic phototrophs, but comprehensive studies of this phenomenon are lacking. Here, we study the effect of blue (450 nm), orange (625 nm), and red (660 nm) light on growth of the model cyanobacterium Synechocystis sp. PCC 6803, the green alga Chlorella sorokiniana and other cyanobacteria containing phycocyanin or phycoerythrin. Our results demonstrate that specific growth rates of the cyanobacteria were similar in orange and red light, but much lower in blue light. Conversely, specific growth rates of the green alga C. sorokiniana were similar in blue and red light, but lower in orange light. Oxygen production rates of Synechocystis sp. PCC 6803 were five-fold lower in blue than in orange and red light at low light intensities but approached the same saturation level in all three colors at high light intensities. Measurements of 77 K fluorescence emission demonstrated a lower ratio of photosystem I to photosystem II (PSI:PSII ratio) and relatively more phycobilisomes associated with PSII (state 1) in blue light than in orange and red light. These results support the hypothesis that blue light, which is not absorbed by phycobilisomes, creates an imbalance between the two photosystems of cyanobacteria with an energy excess at PSI and a deficiency at the PSII-side of the photosynthetic electron transfer chain. Our results help to explain why phycobilisome-containing cyanobacteria use blue light less efficiently than species with chlorophyll-based light-harvesting antennae such as Prochlorococcus, green algae and terrestrial plants.     

Effects of different light quality on growth, chlorophyll concentration and chlorophyll biosynthesis precursors of non-heading Chinese cabbage (Brassica campestris L.)

The aim of this study was to evaluate the effects of different light quality of light emitting diode (LED) on the growth, concentration of chlorophyll and chlorophyll biosynthesis precursors of non-heading Chinese cabbage (Brassica campestris L.). Seedlings of the cultivar Te Ai Qing were cultured for 28 days under 6 treatments: red light (R), blue light (B), green light (G), yellow light (Y), red plus blue light (RB) and dysprosium lamp (CK). Lighting experiments were performed under controlled conditions (photon flux density 150 μmol m^?2 s^?1; 12 h photoperiod; 18–20 °C). The fresh and dry mass were the greatest under RB, which were significantly higher than other light treatments. The fresh mass under RB was almost twice higher compared to other light treatments. Plant height was highest under R treatment and was lowest under B. RB treatment also lowered the plant height significantly. The highest soluble sugar concentration was observed under B. The soluble protein concentration was the greatest under RB. The R treatment was adverse to pigment accumulation. The concentration of photosynthetic pigments and chlorophyll biosynthesis precursors were higher under RB. The RB treatment was beneficial to pigment accumulation.     

Photosynthetic action spectra of trees: I. Comparative photosynthetic action spectra of one deciduous and four coniferous tree species as related to photorespiration and pigment complements

Comparative isoenergetic action spectra of net photosynthesis for intact, current year foliage of five tree species were determined from 400 to 710 nm by CO₂ exchange analysis. The blue (400 to 500 nm) peak of net photosynthetic activity for the green broadleaves of red alder (Alnus rubra Bong.) was reduced to a plateau for the green needle-leaves of Douglas-fir (Pseudotsuga menziesii [Mirb.] Franco) and Sitka spruce (Picea sitchensis [Bong.] Carr.), a shoulder for the blue-green needles of Colorado spruce (Picea pungens Engelm.), and a reduced shoulder for the blue-white needles of Blue spruce (Picea pungens var. hoospii). These differences were attributable neither to a differential blue light stimulation of photorespiration nor to a differential presence of a nonplastid screening pigment. The conifers all had similar carotenoid-chlorophyll ratios, with approximately 50% more carotenoid relative to chlorophyll as compared to red alder. Blue light absorption and low efficiency of energy transfer by the carotenoids probably accounts for the low net photosynthetic activity of the green conifers in blue light as compared to red alder. Leaf form per se (broad versus needle) had no distinguishable influence on these results.     

THE EFFECT OF LIGHT QUALITY ON THE CARBON METABOLISM AND EXTRACELLULAR RELEASE OF CHLAMYDOMONAS REINHARDTII DANGEARD1

The influence of red, blue, green, and white light on growth and photosynthetic rates, carbon metabolism, and rates of release of extracellular compounds in the freshwater alga Chlamydomonas reinhardtii Dangeard was examined. Relative growth constants were 0.28, 0.32, 0.40, and 0.41 in green, white, blue, and red light, respectively. Photosynthetic rates were higher in white, blue, or red than in green light of the same intensity. More than 66% of the ¹⁴CO₂ assimilated by cells grown under blue or green light was incorporated into the ethanol-insoluble fraction, compared with about 50% in cells grown under white or red light. The percentage of sugars in this fraction was significantly higher in cells grown under green or red light than in cells cultured in white or blue light, while the percentage of proteins was highest in blue light. Light quality also influenced the composition of the ethanol-soluble fraction. The percentage of organic acids was highest in cells grown in green and white light, while amino acids were highest in blue and green cultures. The percentage of ethanol-soluble sugars was greatest in cultures grown in blue and red light. The percentage release of dissolved organic carbon into the medium was highest in white light and lowest in blue or red light. The nature of the extracellular products varied according to the quality of light under which the cells were cultured, but had no consistent relation to the nature or concentration or components in the ethanol-soluble fraction.     

不同波长光照对罗汉果光合及生长影响

罗汉果试管苗在不同波长的LED(半导体)蓝(475±5nm)、黄(585±5nm)、红(660±5nm)及普通日光灯下培养,25d后观测发现,其外观的优劣依次为:蓝光>白光>红光>黄光;植株重量:蓝光>红光>黄光>白光;蓝光和白光下的植株叶大、色绿,植株矮壮,侧芽多;红光和黄光下的植株叶小、色黄绿,植株高、细、弯曲、节间长。测定罗汉果成熟叶片的吸收光谱,发现在波长380~500nm及660~680nm处有较强吸收。不同的光质下测定成熟叶片光合速率,大小依次为:红光>蓝光>白光>黄光。上述的各项试验表明,蓝光对罗汉果幼苗生长发育最好;红光和蓝光为成熟叶片光合作用的最佳光源。     

The effect of wavelength of light on stomatal opening

The effect of broad band green, blue and red light on stomatal opening of Vicia faba L. (broad bean) leaves was examined. In air, blue light caused greater stomatal opening than red light. In air with green light stomata were only slightly opened. In a nitrogen atmosphere red light caused greater opening than blue light, and green light caused only slight opening. Opening in air or nitrogen atmosphere in red or blue light was inhibited by the uncoupler CCCP, while the photosynthetic inhibitor DCMU inhibited opening in air but not in nitrogen atmosphere. We concluded that more than one light activated metabolic pathway can supply the energy needed to effect stomatal opening and that different pathways are operative under different conditions.