He-Ne laser-induced improvement in biochemical, physiological, growth and yield characteristics in sunflower (Helianthus annuus L.)

He-Ne Laser Enhances Seed Germination and Salt Acclimation in Salvia officinalis Seedlings in a Manner Dependent on Phytochrome and H2O2

In the current study the role of H₂O₂ in He-Ne laser-induced effects on seed germination and post-germinative performance of Salvia officinalis seedlings was assessed under both non-stress and saline conditions. Salinity had adverse impacts on seed germination and root length and decreased seed germination tolerance index. Seed priming with H₂O₂ and He-Ne laser impacted the seed germination and vigoration in a dose-dependent manner. The optimal effects were gathered by energy dose of 6 J/cm² laser and concentration of 5 mM H₂O₂. These pre-treatments enhanced seed germination due to increasing contents of total soluble and reducing sugars and the amylase activity in seeds and improved seedling performance under saline and non-saline conditions. Furthermore, Phy B transcripts were upregulated, salt-accrued oxidative stress was mitigated, and the activities of POD and CAT increased in seedlings primed with H₂O₂ and laser. Interestingly, applying diphenyleneiodonium (DPI as an inhibitor of NADPH oxidase activity) and N, N-dimethyl thiourea (DMTU as a H₂O₂ scavenger) arrested the upregulation of phy B gene and abolished stimulatory impact of laser priming on the aforementioned attributes under both non-stress and saline conditions. These novel findings suggest that H₂O₂ as a downstream signal modulates the impacts of He-Ne laser on seed germination, seedling performance and salt acclimation in sage seedlings, and likely phy B also is involved in these responses.

The Interaction Effect of Laser Irradiation and 6-Benzylaminopurine Improves the Chemical Composition and Biological Activities of Linseed (Linum usitatissimum) Sprouts

Even though laser light (LL) and 6-benzylaminopurine (BAP) priming are well-known as promising strategies for increasing the growth and nutritional value of several plants, no previous studies have investigated their synergistic effect. Herein, we investigated the effects of laser light, 6-benzylaminopurine (BAP) priming, and combined LL-BAP treatment on the nutritional value, chemical composition, and the biological activity of Linum usitatissimum sprouts. The fresh weight, leaf pigments, primary and secondary metabolites, enzymes, and antimicrobial activities were determined. A substantial enhancement was observed in the growth characteristics and leaf pigments of laser-irradiated and BAP-primed sprouts. Furthermore, the combined treatments improved the accumulation of minerals, vitamins, and amino acids, and also enhanced the N-metabolism more than LL or BAP alone. Furthermore, the combined priming boosted the antioxidant capacity by increasing the contents of fatty acids, phenols, and flavonoids. Antimicrobial activity and the highest increase in bioactive compounds were recorded in linseed sprouts simultaneously treated with LL and BAP. This work suggests that priming L. usitatissimum sprouts with laser light and BAP is a promising approach that can improve the nutritional value and health-promoting impacts of L. usitatissimum sprouts.

Complementary Photostimulation of Seeds and Plants as an Effective Tool for Increasing Crop Productivity and Quality in Light of New Challenges Facing Agriculture in the 21st Century-A Case Study

Climate change has prompted the search for new methods for improving agricultural practices for legume crops. The aim of the study was to test an innovative method of complementary photostimulation of seeds and plants aimed to improve the quantitative and qualitative features of soybean (Glycine hispida L. (Merr.)) yield. Complementary photostimulation of plants was shown to positively affect the yield and chemical composition of soybeans, significantly increasing the content of protein and fat in seeds of the Merlin cultivar. Significant positive effects compared to the control were obtained following irradiation of seeds and plants for 3 s (the shorter of the analyzed exposure times). The results clearly indicate the need to improve the proposed new HUGO (High Utility for Optimal Growth) technology to optimize soybean yield.

Developmental Stages-Specific Response of Anise Plants to Laser-Induced Growth, Nutrients Accumulation, and Essential Oil Metabolism

Compared to seeds and mature tissues, sprouts are well known for their higher nutritive and biological values. Fruits of Pimpinella anisum (anise) are extensively consumed as food additives; however, the sprouting-induced changes in their nutritious metabolites are hardly studied. Herein, we investigated the bioactive metabolites, phytochemicals, and antioxidant properties of fruits, sprouts (9-day-old), and mature tissue (5-week-old) of anise under laser irradiation treatment (He-Ne laser, 632 nm). Laser treatment increased biomass accumulation of both anise sprouts and mature plants. Bioactive primary (e.g., proteins and sugars) and secondary metabolites (e.g., phenolic compounds), as well as mineral levels, were significantly enhanced by sprouting and/or laser light treatment. Meanwhile, laser light has improved the levels of essential oils and their related precursors (e.g., phenylalanine), as well as enzyme activities [e.g., O-methyltransferase and 3-Deoxy-D-arabino-heptulosonate-7-phosphate synthase (DAHPS)] in mature tissues. Moreover, laser light induced higher levels of antioxidant and anti-lipidemic activities in sprouts as compared to fruits and mature tissues. Particularly at the sprouting stage, anise was more responsive to laser light treatment than mature plants.

A Laser Irradiation Method for Controlling Pieris rapae Larvae

At present, chemical pesticides remain the main approach for controlling Pieris rapae (L.) (Lepidoptera: Pieridae). This research proposes a novel laser irradiation method for managing P. rapae larvae as an alternative to chemical control. The effectiveness of controlling larvae and the influencing factors of lasers were studied to estimate optimal parameter combinations. Tests using the antifeedant effect and mortality of the larvae as dependent variables showed that the laser power, irradiation area, laser opening time and irradiation position were positively correlated with the P. rapae controlling effect. The optimal parameters for each factor were the following: laser power, 7.5 W; irradiation area, 6.189 mm2; laser opening time, 1.177 s; and irradiation position, middle of the abdomen. Based on these observations, a validation experiment was performed using the optimal combination of parameters, and the results showed that the antifeedant percentage of P. rapae larvae within 24 h posttreatment was 98.49%, whereas the mortality rate was 100%. The optimal parameter combination identified in the study was suitable for P. rapae larvae from the first- to fifth-instar stages, and a more effective controlling effect was observed with the younger larvae. These results can provide a theoretical basis for future pest control using laser pest-killing robots.

Effect of Laser Light on Growth, Physiology, Accumulation of Phytochemicals, and Biological Activities of Sprouts of Three Brassica Cultivars

Brassica sprouts are known as a good source of antimicrobial bioactive compounds such as phenolics and glucosinolates (GLs). We aim at understanding how He-Ne laser light treatment (632 nm, 5 mW) improves sprout growth and physiology and stimulates the accumulation of bioactive metabolites in three Brassica spp., i.e., mustard, cauliflower, and turnip. Moreover, how these changes consequently promote their biological activities. Laser light improved growth, photosynthesis, and respiration, which induced the accumulation of primary and secondary metabolites. Laser light boosted the levels of pigments, phenolics, and indole and aromatic precursors of GLs, which resulted in increased total GLs and glucoraphanin contents. Moreover, laser light induced the myrosinase activity to provoke GLs hydrolysis to bioactive sulforaphane. Interestingly, laser light also reduced the anti-nutrient content and enhanced the overall biological activities of treated sprouts including antioxidant, antibacterial, anti-inflammatory, and anticancer activities. Accordingly, laser light is a promising approach for boosting the accumulation of beneficial metabolites in Brassica sprouts and, subsequently, their biological activities.

He-Ne Laser Seed Treatment Improves the Nutraceutical Metabolic Pool of Sunflowers and Provides Better Tolerance Against Water Deficit

Water-scarce areas are continually increasing worldwide. This factor reduces the quantity and quality of crops produced in affected areas. Physical seed treatments are considered economical and ecofriendly solutions for such problems. It was hypothesized that a moderately drought-tolerant crop grown from seeds treated with a He-Ne laser utilizes water-limited conditions better than plants grown from untreated seeds. A field study was conducted, growing a moderately drought tolerant crop (sunflower) with supportive seed treatment (He-Ne laser treatment at 300 mJ) for 0, 1, 2, and 3 min. Thirty-day-old plants were subjected to two irrigation conditions: 100% (normal) and 50% (water stress). Harvesting was done at flowering (60-day-old plants) at full maturity. The sunflowers maintained growth and yield under water limitation with a reduced achene number. At 50%, irrigation, there was a reduction in chlorophyll a, a+b and a/b; catalase activity; soluble sugars; and anthocyanin, alongside elevated proline. The improved chlorophyll a, a+b and a/b; metabolisable energy; nutritional value; and yield in the plants grown from He-Ne-laser-treated seeds support our hypothesis. Seeds with 2-min exposure to a He-Ne laser performed best regarding leaf area; leaf number; leaf biomass; chlorophyll a, a+b and a/b; per cent oil yield; 50-achene weight; achene weight per plant; carotenoid content; and total soluble phenolic compound content. Thereafter, the leaves from the best performing level of treatment (2 min) were subjected to high-performance-liquid-chromatography-based phenolic profiling and gas-chromatography-based fatty acid profiling of the oil yield. The He-Ne laser treatment led to the accumulation of nutraceutical phenolic compounds and improved the unsaturated-to-saturated fatty acid ratio of the oil. In conclusion, 2-min He-Ne laser seed treatment could be the best strategy to improve the yield and nutritional value of sunflowers grown in water-limited areas.

He-Ne laser accelerates seed germination by modulating growth hormones and reprogramming metabolism in brinjal

A plant’s ability to maximize seed germination, growth, and photosynthetic productivity depends on its aptitude to sense, evaluate, and respond to the quality, quantity, and direction of the light. Among diverse colors of light possessing different wavelengths and red light shown to have a high impact on the photosynthetic and growth responses of the plants. The use of artificial light sources where the quality, intensity, and duration of exposure can be controlled would be an efficient method to increase the efficiency of the crop plants. The coherent, collimated, and monochromatic properties of laser light sources enabled as biostimulator compared to the normal light. The present study was attempted to use the potential role of the He–Ne laser as a bio-stimulator device to improve the germination and growth of brinjal and to investigate the possible interactions of plant and laser photons. A substantial enhancement was observed in germination index, germination time and seed vigor index of laser-irradiated than control groups. The enhanced germination rate was correlated with higher GA content and its biosynthetic genes whereas decreased ABA content and its catabolic genes and GA/ABA ratio were noted in laser-irradiated groups during seed germination than control groups. Further the expression of phytochrome gene transcripts, PhyA and PhyB1 were upregulated in laser-irradiated seedlings which correlate with enhanced seed germination than control. Elevated levels of primary metabolites were noted in the early stages of germination whereas modulation of secondary metabolites was observed in later growth. Consequently, significantly increased photosynthetic rate, stomatal conductance, and transpiration rate was perceived in laser-irradiated seedlings compare with control. The current study showed hormone and phytochrome-mediated mechanisms of seed germination in laser-irradiated groups along with the enhanced photosynthetic rate, primary and secondary metabolites.

Red laser-mediated alterations in seed germination, growth, pigments and withanolide content of Ashwagandha [Withania somnifera (L.) Dunal]

Withania somnifera (L.) Dunal, generally well-known as Ashwagandha, is part of Indian traditional medicinal systems like Ayurveda, Siddha, and Unani for over 3000 years for treating an array of disorders. The chief bioactive component of this plant is the withanolides, a group of C₂₈-steroidal lactone triterpenoids. These compounds are present in very low concentrations and hence cell culture methods have been used to enhance their production. Low-level laser irradiation has been reported to have elicited the seed germination, agronomical characters, biosynthesis of bioactive compounds in some plants. Therefore, the objective of the study was to investigate the effect of red (He-Ne) laser irradiation on seed germination, growth characters, pigment contents and withanolide content in W. somnifera. The seeds were inoculated onto two different combinations of Murashige and Skoog (MS) media and incubated for germination. The highest germination percentage was observed in ½ MS with pH 6.5 and GA₃ presoaking followed by ½ MS with different pH. Four different doses of Helium-Neon (He-Ne) laser (10, 15, 20 and 25 J/cm²) were used to irradiate the seeds at 632.8 nm and germinated in vitro on ½ MS with pH 6.5. The maximum germination percentage, 63.88% was noted from seeds irradiated with 25 J/cm² (P = 0.04). The highest total length of 13.33 cm was observed in the seedlings irradiated with 25 J/cm² groups (P = 0.008). The highest total chlorophyll content of 329.5 μg/g fresh weight (FW) was observed for seedlings irradiated with 15 J/cm² (P = 0.02) and the highest carotenoid content of 49.6 μg/g FW was observed for 25 J/cm² treated seedlings. Further, primary root length was measured and found to be highest (11.14 cm) in seedlings irradiated with 10 J/cm² and the highest number of lateral roots were observed for 15 and 25 J/cm² groups. The significant amount of Withanolide A (WA) 0.52 μg/g dry weight (DW) and 0.60 μg/g DW was noted in 15 (P = 0.01) and 20 J/cm² (P = 0.002) groups, respectively than control. The present investigation thus reveals the positive impact of red laser on the germination of seeds, growth characters and withanolide contents under in vitro environment.

Laser light as a promising approach to improve the nutritional value, antioxidant capacity and anti-inflammatory activity of flavonoid-rich buckwheat sprouts

Buckwheat sprouts are rich in several nutrients such as antioxidant flavonoids that have a positive impact on human health. Although there are several studies reported the positive impact of laser light on crop plants, no studies have applied laser light to enhance the nutritive values of buckwheat sprouts. Herein, the contents of health-promoting minerals, metabolites and enzymes as well as the antioxidant and anti-inflammatory activities were determined in laser-treated (He-Ne laser, 632 nm, 5 mW) common buckwheat (CBW) and tartarybuckwheat (TBW) sprouts. Out of 49 targeted minerals, vitamins, pigments and antioxidants, more than 35 parameters were significantly increased in CBW and/or TBW sprouts by laser light treatment. Also, laser light boosted the antioxidant capacity and anti-inflammatory activities through inhibiting cyclooxygenase-2 and lipoxygenase activities, particularly in TBW sprouts. Accordingly, laser light could be recommended as a promising method to improve the nutritional and health-promoting values of buckwheat sprouts.

Effect of Long-Term of He-Ne Laser Light Irradiation on Selected Physiological Processes of Triticale

In agriculture, the bio-stimulating properties of laser light increase the yielding capacity of crop species. The experiment aimed to determine the pre-sowing effect of irradiation time with laser He-Ne red light of triticale grains (×Triticosecale Wittm. ex A.Camus) on germination and selected morphological and physiological parameters of seedlings and plants grown from them. The highest values of germination indexes were found for grains irradiated with laser for 3 h. In relation to the control, the elongation growth of seedlings was stimulated in grains irradiated with light for 3 h and inhibited for 24 h. The values of the fresh and dry mass of seedlings changed depending on the exposure time. He-Ne light did not significantly affect the degree of destabilization of seedling cell membranes. Biometric analysis of plants grown from irradiated grains showed different reactions of triticale organs to the irradiation time. Red light clearly stimulated the increase in the value of organ mass. Chlorophyll content in leaves was higher in plants grown from grains irradiated for 3 h. Photosynthetic activity did not change significantly relative to the control. The fluorescence emission indexes were mostly lower than in the control, which indicated a positive effect of the laser. In general, the red light of the laser stimulated the morphology and physiology of seedlings and plants, although, for some features, long exposure to red light caused a slight reduction effect.

Innovative application of helium-neon laser: enhancing the germination of Adansonia digitata and evaluating the hepatoprotective activities in mice

The laser pretreatment of seed is drawing pronounced attention from the scientific community for its positive impact in boosting germination, seedling , and growth of plants. In this study, the laser pretreatment of Adansonia digitata (A. digitata) seeds was evaluated. Eight laser treatments were conducted at different powers, 10, 20, 40, and 80 mW, with the two-time interval for each power at 2 and 4 min. The outcomes indicated that the most efficient irradiation was 10 mW/2 min which induces the highest germination rate and polyphenolic contents for seeds. Based on these results, the animal experimental design was processed to assess the hepatoprotective activity of A. digitata extracts obtained through the optimum laser preillumination to enhance the resistance of liver damage in mice. The total phenol and flavonoid contents and the antioxidant properties of the methanolic extracts were estimated in vitro. The CCl4 was used to induce hepatotoxicity in mice. The animals were divided into five groups. The sera of the treated animals were used for the determination of transaminases, and the liver homogenates were used for the determination of antioxidant status, and further liver tissues were subjected to verify the anti-apoptotic effect of A. digitata methanolic extract. The in vivo results showed that the methanolic extract exposed to laser treatment at 10 mW/2 min provided better hepatoprotective capacity than the other treatments. Administration of A. digitata extract not only offered a significant decrease in liver enzyme activity but also markedly improved the antioxidant status and reduced the apoptotic progression induced by CCl4 toxicity in liver tissue.

Involvement of Photoprotective Compounds of a Phenolic Nature in the Response of Arabidopsis Thaliana Leaf Tissues to Low-Intensity Laser Radiation

The influence of low-intensity laser radiation (LILR) on the changes in the content of anthocyanins, kaempferol, quercetin and their glycosides in the leaves of 5-week-old plants of Arabidopsis thaliana L. was studied by means of methods of high-performance liquid chromatography and gas chromatography mass spectrometry (GC-MS). It was found that in the leaves subjected to a stimulating He-Ne laser radiation dose (3.6 J cm^-2 , continuous wave radiation, wavelength-632.8 nm, exposure time-5 min), the radiation induced an increase in the content of such compounds, the most significant one being in the case of anthocyanins (9 times). The present study also revealed an increase in the antioxidant potential of kaempferol, quercetin and their glycosides as a result of laser exposure. This increase was due to the preferential synthesis of compounds with a larger number of OH-groups on the phenyl ring. Thus, the content of quercetin, which has five OH-groups in its structure, increased almost by three times as compared to the control.

Characterization of miRNAs and their target genes in He-Ne laser pretreated wheat seedlings exposed to drought stress

Drought stress is considered a critical environmental factor that negatively affects wheat growth and development, which causes considerable losses in wheat yields worldwide. More recently, numerous microRNAs (miRNAs) have been found to be involved in wheat responses to drought stresses. However, there is little information regarding the effects of He-Ne laser irradiation on the expression traits of miRNAs and their targets in wheat seedlings exposed to drought stress. In the current study, therefore, a combination of physiological and molecular approaches was used to assess the effect of He-Ne laser irradiation on the expression of miRNAs and their targets in wheat seedlings exposed to drought stress. Our results demonstrated that drought stress significantly reduced plant height, root length, shoot and root fresh weight, relative water content, the expression level and activity of superoxide dismutase (SOD), enhanced malondialdehyde (MDA) concentration in the wheat seedlings. However, He-Ne laser irradiation significantly enhanced the activities of SOD, ascorbate peroxidase (APX), peroxidase (POD) and relative water content, and reduced MDA concentration of seedlings by regulating gene expression for SOD, POD, APX. In addition, in comparison with drought stress alone, miR160, miR164 and miR398 transcripts were down-regulated, and expression levels of its targets auxin response factor (ARF22), NAC domain transcription factor and Cu/Zn superoxide dismutases (CSD) were up-regulated in He-Ne laser irradiated seedlings exposed to drought stress. These results suggested that He-Ne laser irradiation could possible protection of drought stress, at least partially, by increasing the transcript levels and activities of SOD, POD and APX, and decreasing the transcript levels of miR160, miR164 and miR398. To the best of our knowledge, this is the first study to present biochemical and molecular evidence supporting the effect of He-Ne laser irradiation on the alleviation of drought stress in wheat seedlings mediated by miRNA expression.

Effect of Electromagnetic Stimulation of Amaranth Seeds of Different Initial Moisture on the Germination Parameters and Photosynthetic Pigments Content

The influence of stimulation with He-Ne laser light, alternating magnetic field and the combination of these factors on germination parameters of amaranth seeds and on the chlorophyll and carotenoid content in seedlings was investigated. During the stimulation the amaranth seeds had a different initial moisture content. From the germination characteristics of the seeds as the function of humidity, three maxima and one minimum value of the germination parameters (the relative germination capacity N_{K REL}, the relative maximum germination rate S_{K MAX REL} and the maximum germination index W_{K MAX}) were obtained. In the majority of cases, the extremities coincided with the changes in the chlorophyll and carotenoid content in the seedlings. The presented research is innovative in the field of seed biology since no similar studies have been conducted before. It is difficult to interpret the results referring to the literature on this subject. The results can be explained as follows: the observed effect must be related to the stages of the water uptake by the seeds. The three stages of the water uptake associated with the seed germination process coincide with the maximum values in the germination parameters and with the change in the photosynthetic pigment content in seedlings.

Responses of He-Ne laser on agronomic traits and the crosstalk between UVR8 signaling and phytochrome B signaling pathway in Arabidopsis thaliana subjected to supplementary ultraviolet-B (UV-B) stress

UV-B acclimation effects and UV-B damage repair induced by a 632.8-nm He-Ne laser were investigated in Arabidopsis thaliana plants in response to supplementary UV-B stress. There was an increasing trend in growth parameters in the combination-treated plants with He-Ne laser and UV-B light compared to those stressed with enhanced UV-B light alone during different developmental stages of plants. The photosynthetic efficiency (Pn) and survival rates of seedlings were significantly higher in the combination treatments than UV-B stress alone. The expression of UVR8, phytochrome B (PhyB), and their mediated signal responsive genes such as COP1, HY5, and CHS were also significantly upregulated in plants with the laser irradiation compared with other groups without the laser. Levels of flavonol accumulation in leaves and capsule yield of He-Ne laser-treated plants were increased. The phyB-9 mutants were more sensitive to enhanced UV-B stress and had no obvious improvements in plant phenotypic development and physiological damage caused by enhanced UV-B stress after He-Ne laser irradiation. Our results suggested that UVR8 and its mediated signaling pathway via interaction with COP1 can be induced by He-Ne laser, and these processes were dependent on cytoplasmic PhyB levels in plant cells, which might be one of the most important mechanisms of He-Ne laser on UV-B protection and UV-B damage repair. These current data have also elucidated that the biostimulatory effects of He-Ne laser on Arabidopsis thaliana plants would happen not only during the early growth stage but also during the entire late developmental stage.

Physiological and transcriptome analysis of He-Ne laser pretreated wheat seedlings in response to drought stress

Drought stress is a serious problem worldwide that reduces crop productivity. The laser has been shown to play a positive physiological role in enhancing plant seedlings tolerance to various abiotic stresses. However, little information is available about the molecular mechanism of He-Ne laser irradiation induced physiological changes for wheat adapting to drought conditions. Here, we performed a large-scale transcriptome sequencing to determine the molecular roles of He-Ne laser pretreated wheat seedlings under drought stress. There were 98.822 transcripts identified, and, among them, 820 transcripts were found to be differentially expressed in He-Ne laser pretreated wheat seedlings under drought stress compared with drought stress alone. Furthermore, most representative transcripts related to photosynthesis, nutrient uptake and transport, homeostasis control of reactive oxygen species and transcriptional regulation were expressed predominantly in He-Ne laser pretreated wheat seedlings. Thus, the up-regulated physiological processes of photosynthesis, antioxidation and osmotic accumulation because of the modified expressions of the related genes could contribute to the enhanced drought tolerance induced by He-Ne laser pretreatment. These findings will expand our understanding of the complex molecular events associated with drought tolerance conferred by laser irradiation in wheat and provide abundant genetic resources for future studies on plant adaptability to environmental stresses.

Comparison of HeNe laser and sinusoidal non-uniform magnetic field seed pre-sowing treatment effect on Glycine max (Var 90-I) germination, growth and yield

Recently, laser and magnetic field pre-sowing seed treatments attracted the attention of the scientific community in response to their positive effect on plant characteristics and the present study was exemplified for Glycine max Var 90-I. Seeds were exposed to laser (HeNe-wave length 632nm and density power of 1mW/cm2) and magnetic field (sinusoidal non-uniform-50, 75 and 100mT for 3, 5min with exposure) and seed germination, seedling growth and yield attributes were compared. The germination (mean germination, germination percentage, emergence index, germination speed, relative germination coefficient, emergence coefficient of uniformity) growth (root dry weight, root length, shoot fresh weight and shoot dry weight, leaf dry & fresh weight, root fresh weight, leaf area, shoot length, plant total dry weight at different stages, stem diameter, number of leaves, vigor index I & II), biochemical (essential oil) and yield attributes (seed weight, count) were enhanced significantly in response to both laser and magnetic field treatments. However, magnetic field treatment furnished slightly higher response versus laser except relative water contents, whole plant weight and shoot length. Results revealed that both laser and magnetic field pre-sowing seed treatments affect the germination, seedling growth, and yield characteristics positively and could possibly be used to enhance Glycine max productivity.

A combination of He-Ne laser irradiation and exogenous NO application efficiently protect wheat seedling from oxidative stress caused by elevated UV-B stress

The elevated ultraviolet-B (UV-B) stress induces the accumulation of a variety of intracellular reactive oxygen species (ROS), which seems to cause oxidative stress for plants. To date, very little work has been done to evaluate the biological effects of a combined treatment with He-Ne laser irradiation and exogenous nitric oxide (NO) application on oxidative stress resulting from UV-B radiation. Thus, our study investigated the effects of a combination with He-Ne laser irradiation and exogenous NO treatment on oxidative damages in wheat seedlings under elevated UV-B stress. Our data showed that the reductions in ROS levels, membrane damage parameters, while the increments in antioxidant contents and antioxidant enzyme activity caused by a combination with He-Ne laser and exogenous NO treatment were greater than those of each individual treatment. Furthermore, these treatments had a similar effect on transcriptional activities of plant antioxidant enzymes. This implied that the protective effects of a combination with He-Ne laser irradiation and exogenous NO treatment on oxidative stress resulting from UV-B radiation was more efficient than each individual treatment with He-Ne laser or NO molecule. Our findings might provide beneficial theoretical references for identifying some effective new pathways for plant UV-B protection.

Laser light and magnetic field stimulation effect on biochemical, enzymes activities and chlorophyll contents in soybean seeds and seedlings during early growth stages

Laser and magnetic field bio-stimulation attracted the keen interest of scientific community in view of their potential to enhance seed germination, seedling growth, physiological, biochemical and yield attributes of plants, cereal crops and vegetables. Present study was conducted to appraise the laser and magnetic field pre-sowing seed treatment effects on soybean sugar, protein, nitrogen, hydrogen peroxide (H2O2) ascorbic acid (AsA), proline, phenolic and malondialdehyde (MDA) along with chlorophyll contents (Chl "a" "b" and total chlorophyll contents). Specific activities of enzymes such as protease (PRT), amylase (AMY), catalyst (CAT), superoxide dismutase (SOD) and peroxides (POD) were also assayed. The specific activity of enzymes (during germination and early growth), biochemical and chlorophyll contents were enhanced significantly under the effect of both laser and magnetic pre-sowing treatments. Magnetic field treatment effect was slightly higher than laser treatment except PRT, AMY and ascorbic acid contents. However, both treatments (laser and magnetic field) effects were significantly higher versus control (un-treated seeds). Results revealed that laser and magnetic field pre-sowing seed treatments have potential to enhance soybean biological moieties, chlorophyll contents and metabolically important enzymes (degrade stored food and scavenge reactive oxygen species). Future study should be focused on growth characteristics at later stages and yield attributes.

Effects of laser irradiation on a bloom forming cyanobacterium Microcystis aeruginosa

Effects of laser irradiation on photosystem II (PS II) photochemical efficiencies, growth, and other physiological responses of Microcystis aeruginosa were investigated in this study. Results indicate that laser irradiation (wavelengths 405, 450, 532, and 650 nm) could effectively inhibit maximal PS II quantum yield (Fv/Fm) and maximal electron transport rates (ETR_max) of M. aeruginosa, while saturating light levels (E_k) of M. aeruginosa did not change significantly. Among the four tested wavelengths, 650 nm laser (red light) showed the highest inhibitory efficiency. Following 650 nm laser irradiation, the growth of M. aeruginosa was significantly suppressed, and contents of cellular photosynthetic pigments (chlorophyll a, carotenoid, phycocyanin, and allophycocyanin) decreased as irradiation dose increased. Meanwhile, laser irradiation enhanced the enzyme activities of superoxide dismutase (SOD) and peroxidase (POD) in M. aeruginosa cells. Lower irradiation doses did not change the intracellular microcystin contents, but higher dose irradiation (>1284 J cm^-2) caused the release of microcystin into the culture medium. Transmission electron microscope examination showed that the ultrastructure of M. aeruginosa cells was destructed progressively following laser irradiation. Effects of laser irradiation on M. aeruginosa may be a combination of photochemical, electromagnetic, and thermal effects.

He-Ne laser preillumination improves the resistance of tall fescue (Festuca arundinacea Schreb.) seedlings to high saline conditions

In this paper, we explored the protective effect and physiochemical mechanism of He-Ne laser preillumination in enhancement of tall fescue seedlings tolerance to high salt stress. The results showed that salt stress greatly reduced plant growth, plant height, biomass, leaf development, ascorbate acid (AsA) and glutathione (GSH) concentration, the enzymatic activities, and gene expression levels of antioxidant enzymes such as catalase (CAT) and glutathione reductase (GR) and enhanced hydrogen peroxide (H2O2) content, superoxide radical (O2 (·-)) generation rates, membrane lipid peroxidation, relative electrolyte leakage, the enzymatic activities, and gene expression levels of superoxide dismutase (SOD), ascorbate peroxidase (APX), and peroxidase (POD), compared with controls. However, He-Ne laser preillumination significantly reversed plant growth retardation, biomass loss, and leaves development decay induced by salt stress. And the values of the physiochemical parameters observed in salt-stressed plants were partially reverted or further increased by He-Ne laser. Salt stress had no obvious effect on the transcriptional activity of phytochromeB, whereas He-Ne laser markedly enhanced its transcriptional level. Preillumination with white fluorescent lamps (W), red light (RL) of the same wavelength, or RL, then far-red light (FRL) had not alleviated the inhibitory effect of salt stress on plant growth and antioxidant enzymes activities, suggesting that the effect of He-Ne laser on improved salt tolerance was most likely attributed to the induction of phytochromeB transcription activities by the laser preillumination, but not RL, FRL or other light sources. In addition, we also utilized sodium nitroprusside (SNP) as NO donor to pre-treat tall fescue seedlings at the same conditions, and further evaluated the differences of physiological effects between He-Ne laser and NO in increasing salt resistance of tall fescue. Taken together, our data illustrated that He-Ne laser preillumination contributed to conferring an increased tolerance to salt stress in tall fescue seedlings due to alleviating oxidative damage through scavenging free radicals and inducing transcriptional activities of some genes involved in plant antioxidant system, and the induction of phytochromeB transcriptional level by He-Ne laser was probably correlated with these processes. Moreover, this positive physiochemical effect seemed more effective with He-Ne laser than NO molecule.

He-Ne laser pretreatment protects wheat seedlings against cadmium-induced oxidative stress

The aim of the investigation is to determine the effect of He-Ne laser pretreatment of wheat seeds on the resistance of seedlings to cadmium stress. Changes in physiological, biochemical and molecular characters were measured. Our results showed that 150 μM Cd treatment significantly reduced plant height, root length, shoot fresh weight, shoot dry weight, root fresh weight, root dry weight, ascorbate acid (AsA) and glutathione (GSH) concentration, the activities of superoxide dismutase (SOD), peroxidase (POD), catalase (CAT), ascorbate peroxidase (APX) and gene expression levels of SOD, APX, enhanced the concentration of malondialdehyde (MDA), hydrogen peroxide (H(2)O(2)) and the rate of superoxide radical (O(2)(•-)) generation in the wheat seedlings when compared with the control. However, seeds with He-Ne laser pretreatment 5 min conferred tolerance to cadmium stress in wheat seedlings by decreasing the concentration of MDA and H(2)O(2), the rate of O(2)(•-) generation and increasing the gene expression levels of SOD, POD, APX, the activities of SOD, POD, CAT, APX and AsA and GSH concentration. These results suggest that those changes in MDA, O(2)(•-), H(2)O(2), anti-oxidative enzymes, gene expression level and anti-oxidative compounds are responsible for the increase in cadmium stress resistance observed in the experiments. The results also showed that the laser had a positive physiological effect on the growth of cadmium stressed seedlings. This is the first investigation reporting the use of He-Ne laser pretreatment to enhance of wheat seedlings tolerance to cadmium stress.