Levels Of Photosynthetic Pigments Research Articles

Response of Lawn Grasses to Salinity Stress and Protective Potassium Effect

The salinity effects on lawn grasses caused by mine salts (halite and carnallitite) due to road de-icing processes was the aim of this study. Biometric and physiological parameters were evaluated after salt dosage of 50 and 100 g m−2 applied to a lawn surface twice and four times, in weekly intervals. The alleviating effect to the salinity on the grasses from potassium enriched soil was also evaluated. Protective effect of potassium included mostly plasma membrane integrity and an increase in the level of photosynthetic pigments. This probably resulted in more efficient photosynthesis and thus increased lawn growth. Simultaneously, only a slight reduction in relative water content (RWC) was noted, so the recorded increase in proline level may indicate its participation in osmotic adjustment. Our results confirm the importance of proper, and even over-optimal, potassium fertilization of lawn grasses exposed to salinity. Moreover, it is advisable to use other fossil salts instead of halite for the de-icing of near-green areas. The mined salt carnallitite which, besides NaCl, contains about 30% of carnalite (KCl·MgCl2·6H2O) could be such a substance.

Mitigation of the effect of drought on growth and yield of pomegranates by foliar spraying of different sizes of selenium nanoparticles.

Drought is a very important environmental stressor, which has negative effects on the growth of trees, decreasing their yield. The role of different-sized selenium nanoparticles (Se-NPs) in the mitigation of environmental stresses such as drought in crops has not yet been investigated. Trees treated with Se-NPs displayed higher levels of photosynthetic pigments, a better nutrient status, better physical parameters (especially fruit cracking) and chemical parameters, a higher phenolic content, and higher concentrations of osmolytes, antioxidant enzymes, and abscisic acid than untreated trees under drought stress. Foliar spraying of 10 and 50 nm Se-NPs alleviated many of the deleterious effects of drought in pomegranate leaves and fruits and this was achieved by reducing stress-induced lipid peroxidation and H2 O2 content by enhancing the activity of antioxidant enzymes. Furthermore, the 10nm Se-NPs treatment produced more noticeable effects than the treatment with 50 nm Se-NPs. Results confirm the positive effects of nanoparticle spraying, especially the role of 10nm Se-NPs in the management of negative effects of drought not only for pomegranates but potentially also for other crops. © 2021 Society of Chemical Industry.

Maghemite nano-fertilization promotes fluoride tolerance in rice by restoring grain yield and modulating the ionome and physiome

The present manuscript elucidated the ameliorative potential of nano-maghemite (FeNPs) against the hazardous effects of fluoride toxicity in the sensitive rice cultivar, IR-64. Fluoride pollution triggered bioaccumulation in root, shoot and spikelets which inhibited reproduction, agronomic development and mineral uptake. Suppressed activity of enzymatic antioxidants and excessive cobalt translocation manifested severe ROS-induced oxidative injuries. Seedling priming with FeNPs reduced fluoride bioaccumulation and promoted efficient uptake of macroelements and micronutrients like potassium, calcium, iron, zinc, copper, nickel, manganese, selenium and vanadium and reduced the translocation of cobalt in mature seedlings during stress. This altogether triggered growth and activated the enzymes like SOD, CAT, APX and GPOX. High accumulation of non-enzymatic antioxidants like proline, anthocyanins, flavonoids, phenolics along with stimulated GSH synthesis (determined from high GR, GST and GPX activity) and glyoxalase activity enabled FeNP-pulsed plants to efficiently scavenge ROS, O2-, H2O2 and methylglyoxal, and mitigate oxidative injuries. The ROS production was also lowered due to suppressed NADPH oxidase activity. This ensured subsequent revitalization of Hill activity and the level of photosynthetic pigments. Due to reduced fluoride partitioning and improved nutritional sink, the grain and panicle development in FeNP-primed, stressed seedlings were more stimulated than even control sets. Overall, our findings supported by statistical modelling established the potential of iron-nanotechnology in promoting safe rice cultivation even in fluoride-polluted environments.

Application of Light-Emitting Diodes for Improving the Nutritional Quality and Bioactive Compound Levels of Some Crops and Medicinal Plants.

Light is a key factor that affects phytochemical synthesis and accumulation in plants. Due to limitations of the environment or cultivated land, there is an urgent need to develop indoor cultivation systems to obtain higher yields with increased phytochemical concentrations using convenient light sources. Light-emitting diodes (LEDs) have several advantages, including consumption of lesser power, longer half-life, higher efficacy, and wider variation in the spectral wavelength than traditional light sources; therefore, these devices are preferred for in vitro culture and indoor plant growth. Moreover, LED irradiation of seedlings enhances plant biomass, nutrient and secondary metabolite levels, and antioxidant properties. Specifically, red and blue LED irradiation exerts strong effects on photosynthesis, stomatal functioning, phototropism, photomorphogenesis, and photosynthetic pigment levels. Additionally, ex vitro plantlet development and acclimatization can be enhanced by regulating the spectral properties of LEDs. Applying an appropriate LED spectral wavelength significantly increases antioxidant enzyme activity in plants, thereby enhancing the cell defense system and providing protection from oxidative damage. Since different plant species respond differently to lighting in the cultivation environment, it is necessary to evaluate specific wavebands before large-scale LED application for controlled in vitro plant growth. This review focuses on the most recent advances and applications of LEDs for in vitro culture organogenesis. The mechanisms underlying the production of different phytochemicals, including phenolics, flavonoids, carotenoids, anthocyanins, and antioxidant enzymes, have also been discussed.

Enzymatic response to cadmium by Impatiens glandulifera: A preliminary investigation

This paper aims to develop our understanding of the effect of cadmium (Cd) on Impatiens glandulifera, a recently identified potential Cd hyperaccumulator. Impatiens glandulifera plants were exposed to three concentrations of Cd (20, 60 and 90 mg/kg) and were sampled at two timepoints (one and seven days) to investigate the stress response of I. glandulifera to Cd. Cd can induce oxidative stress in plants, triggering overproduction of reactive oxygen species (ROS). The level of activity of catalase (CAT) and ascorbate peroxidase (APX), two crucial antioxidant enzymes responsible for detoxifying ROS, were found to increase in a concentration dependent manner. Though there was no change observed in the level of superoxide dismutase (SOD) activity, the activity of glutathione S-transferase (GST), involved in detoxifying and sequestering Cd, increased after exposure to Cd. Cd did not appear to impact the levels of proline and photosynthetic pigments, indicating the plants weren't stressed by the presence of Cd. These results suggest that the rapid response observed in enzyme activity aid the efficacious mitigation of the toxic effects of Cd, preventing significant physiological stress in I. glandulifera.

Silicon Supplied Via Roots or Leaves Relieves Potassium Deficiency in Maize Plants

The aim of this study was to determine whether silicon (Si) supplied via nutrient solution or foliar spray is nutritionally and physiologically efficient in mitigating potassium (K) deficiency in maize plants. To that end, an experiment was conducted in a greenhouse with maize plants grown in a hydroponic system. The treatments included two levels of K, i.e. K deficient (0.2 mmol L−1 of K) and K-sufficient (6 mmol L−1 of K). Under both these conditions, Si was supplied through stabilized potassium sodium silicate via nutrient solution (2 mmol L−1 of Si) or foliar spray (5.3 mmol L−1 of Si) and control (0 mmol L−1 of Si), using a completely randomized design and four repetitions. Potassium deficiency without the addition of Si showed less accumulation of K and Si and lower levels of photosynthetic pigments. It also caused the reduction in gas exchange and, consequently, a reduction in vegetative development. However, Si relieved K-deficiency stress in maize plants, since it improved nutritional, physiological and growth variables. The application of Si to K-deficient maize plants improved their water use efficiency, their chlorophyll and carotenoid contents, and their dry matter production. This effect was more evident in the treatment of Si via roots.

Field- and laboratory-based methods of screening salt tolerant genotypes in rice

Salinity is one of the major abiotic stresses that lead to loss of billions of dollars in crop production worldwide. The growth of rice plant is severely affected and subsequently the yield is generally low in salt affected areas. Salinity affects rice primarily at the early vegetative stage by interfering with biochemical and physiological processes governing its growth and development. This review aims at summarising various morphological, physiological, biochemical, and molecular-based methods that are currently used in screening salt-tolerant rice genotypes at different growth stages with particular emphasis on screening of breeding lines, and also the effectiveness of these methods. Field and laboratory-based methods are described including visual screening of salt-induced injuries as per the IRRI’s standard evaluation system, salt-induced accumulation of ions, changes in the levels of photosynthetic pigments, antioxidant, and image-based visual quantification of injuries, and molecular markers-based screening, which are lengthy and cumbersome. Among these methods currently available, this review highlights IC50 (50% inhibition concentration) estimation of shoot growth inhibition as a rapid and accurate method that can differentiate genotypes with the IC50 difference of only a few mm NaCl for the initial screening of a large number of rice germplasm and breeding lines.

Effect of presowing seed treatment on photosynthetic pigments content and enzyme activity in Hordeumvulgare L. plants

The use of nanoparticles in pre-sowing seed treatment increases the resistance of plants to pathogenic microflora, adverse weather conditions and increases the yield of crops. The study aimed to study the effect of molybdenum nanoparticles, a suspension of iron and silicon and preparations based on humic acids on the content of photosynthetic pigments, the activity of antioxidant enzymes in Hordeumvulgare L. plants and its productivity. The content of chlorophyll a and b, carotenoids in different phases of plant development was determined using the standard method with Smashevsky modifications, catalytic activity according to the Ebi method, superoxide dismutase according to Hyannopolitis and Rice with some modifications of Polesskaya. Barley seed treatment with preparations based on iron, silicon, molybumum, bogum and molybdenum nanoparticles M Mo stimulates an increase in the level of photosynthetic pigments and the activity of antioxidant enzymes in plants. Using a composition created based on Fe3O4 (10–3 mg/L) and SiO2 (10–4 mg/L) nanoparticles in a 1: 1 ratio for the presowing treatment of barley seeds increases grain yield.

Effects of road traffic on photosynthetic pigments and heavy metal accumulation in tree species of Kumasi Metropolis, Ghana

This study was undertaken to examine changes in the content of pigments and accumulation of metals from vehicular pollution in selected species of roadside trees under vehicular pollution. A major arterial road with heavy vehicle emissions in the Kumasi Metropolis was designated as the polluted site, while Kwame Nkrumah University of Science and Technology Campus was designated as the control site. Four tree species (Terminalia catappa, Mangifera indica, Ficus platyphylla and Polyalthia longifolia) selected for the study were well distributed and abundant in the polluted and control sites. Photosynthetic pigments and levels of heavy metals (Pb, Cu, Cd and zinc) were assessed in their leaves. Chlorophyll and carotenoid contents were determined by absorption spectrometry, while the metal accumulation index (MAI) was used to determine the total metal accumulation capacity of the tree species. We observed a reduction in photosynthetic pigments in the leaf samples from the polluted site. Ficus platyphylla had the maximum reduction in total chlorophyll (49.34%), whereas Terminalia catappa recorded the lowest reduction (33.88%). Similarly, the largest decrease (31.58%) of carotenoid content was found in Terminalia catappa trees and the lowest in Polyalthia longifolia (16.67%). The Polyalthia longifolia, Ficus platyphylla and Terminalia catappa leaf samples collected at the polluted site recorded a higher ratio of chlorophyll a/b. Heavy metal (Cu, Pb, Zn and Cd) accumulation in leaf samples was higher in the polluted site than in the control, as expected. The highest metal MAI value was recorded in Mangifera indica (5.35) followed by Polyalthia longifolia with 4.30. The findings from this study specifically demonstrate that air contamination induced by vehicles decreases the level of photosynthetic pigments in trees subjected to roadside emissions. It is clear that both chlorophyll a/b and chlorophyll/carotenoid ratios will act as very useful stress-level markers. Elevated heavy metal levels in the tree species along arterial roadsides indicate that they serve as heavy metals sink. The change in MAI resulting from different pollution burden is an indication that the removal capabilities of the tree species differ from each other. We therefore suggest M. indica and P. longifolia as potential species to be used in air pollution reduction plans in the city.

Métodos de aplicação de peróxido de hidrogênio em mudas de gravioleira irrigadas com água salina

A aclimatação das plantas ao estresse salino, por meio de aplicação de peróxido de hidrogênio, ocorre devido à ativação do sistema de defesa antioxidante. Neste sentido, objetivou-se com o estudo avaliar os teores de pigmentos fotossintéticos e a eficiência fotoquímica de mudas de gravioleira sob irrigação com águas salinas e distintos métodos de aplicação de peróxido de hidrogênio. O estudo foi realizado em condições de casa de vegetação, em esquema 5 x 4, sendo cinco níveis de condutividade elétrica da água de irrigação – CEa (0,6; 1,2; 1,8; 2,4 e 3,0 dS m-1) e quatro métodos de aplicação de peróxido de hidrogênio- MA (sem aplicação de H2O2, aplicação via embebição das sementes, aplicação via pulverização foliar e aplicação via embebição das sementes e pulverização foliar). A salinidade da água de irrigação até 1,4 e 1,1 dS m-1provocou aumento na síntese de clorofila b e carotenoides, respectivamente. Já a irrigação com água a partir de 0,6 dS m-1 reduziu a síntese de clorofila a e total das plantas de gravioleira. A aplicação de 20 μm de H2O2via embebição da semente resulta em aumento nos teores de clorofila a e b, total, fluorescência máxima e variável das mudas de gravioleira.A embebição das sementes com peróxido de hidrogênio aumentou a fluorescência inicial da clorofila nas plantas irrigadas com água de 1,2 dS m-1.

Corylus avellana bark optical properties differ during and out of the vegetation season

We compared different bark traits of the common hazel (Corylus avellana L.) in four different months during the vegetation season (September, November) and out of the vegetation season (January, February) to get an insight into the changes in bark morphological, biochemical, and optical properties. Since bark of woody plants contains a layer of chlorenchyma, which can harvest transmitted light and perform photosynthesis, we also measured bark potential photochemical efficiency of photosystem II. The values of the latter parameter decreased during the research period, ranging from 0.77 in September to 0.22 in February. This could be attributed to low temperatures. The shapes of the bark reflectance curves were similar between the four samplings, with a peak in red and pronounced reflectance in the near-infrared spectrum. However, the level of reflectance differed between the four samplings. Regarding the time of the season, we obtained the most pronounced changes in the green, yellow, and red reflectance spectra. Light reflectance in these regions was positively related with chlorophyll b and carotenoid contents, while it was negatively related with anthocyanins and UV-B–absorbing substances. Transmittance spectra showed less variability between the four samplings. Regarding the studied pigments, the most pronounced changes were obtained for anthocyanin and UV-B–absorbing substances contents, which decreased in accordance with decreasing environmental temperatures. On the contrary, the level of photosynthetic pigments remained high, thus enabling undisturbed primary metabolism.

Leaf Response to Different Light Spectrum Compositions during Micropropagation of Gerbera Axillary Shoots

The experiment evaluated the influence of different light qualities and 6-benzyladenine (BA) concentration in a medium on the leaf response of multiplied Gerbera jamesonii Bolus ex Hook. f.‘Big Apple’ shoots. Three different light-emitting diode (LED) spectra—100% blue (B), 100% red (R) and red and blue mixture (7:3, RB)—were used, and a fluorescent lamp was used as a control (Fl). Concentrations of BA in Murashige and Skoog (MS) medium were 1, 2.5 and 5 µM. Leaves developed under 100% blue light had a lower frequency of stomata and a smaller area as compared with those from plants exposed to light with red in spectrum. Under 100% red light, the leaf area and the frequency of stomata increased along with growing concentration of BA in the medium. The thickest mesophyll was spotted in the cross-section of leaves exposed to the blue LED light. Leaves developed under the 100% red light had the thinnest mesophyll layers. Increasing concentration of BA in the medium resulted in enhanced leaf blade thickness. The cross-section of leaf vascular bundles was only half of that in petioles. The leaves under the LED combinations had larger vascular bundles than those under fluorescent light. The highest level of photosynthetic pigments was noticed in the leaves grown under LED R and RB lights. Our study demonstrated that 2.5 µM BA and a mixture of blue and red light provided by LED improved leaf quality during multiplication of gerbera shoots.

The rice LRR-like1 protein YELLOW AND PREMATURE DWARF 1 is involved in leaf senescence induced by high light.

Senescence in plants is induced by endogenous physiological changes and exogenous stresses. In this study, we isolated two alleles of a novel rice (Oryza sativa) mutant, yellow and premature dwarf 1 (ypd1). The ypd1 mutants exhibited a yellow and dwarf phenotype from germination, and premature senescence starting at tillering. Moreover, the ypd1 mutants were sensitive to high light, which accelerated cell death and senescence. Consistent with their yellow phenotype, the ypd1 mutants had abnormal chloroplasts and lower levels of photosynthetic pigments. TUNEL assays together with histochemical staining demonstrated that ypd1 mutants showed cell death and that they accumulated reactive oxygen species. The ypd1 mutants also showed increased expression of genes associated with senescence. Map-based cloning revealed a G→A substitution in exon 6 (ypd1-1) and exon 13 (ypd1-2) of LOC_Os06g13050 that affected splicing and caused premature termination of the encoded protein. YPD1 was found to be preferentially expressed in the leaf and it encodes a LRR-like1 protein. Complementation, overexpression, and targeted deletion confirmed that the mutations in YPD1 caused the ypd1 phenotype. YPD1 was localized on the chloroplast membrane. Our results thus demonstrate that the novel rice LRR-like1 protein YPD1 affects chloroplast development and leaf senescence.

Examining the uptake and bioaccumulation of molybdenum nanoparticles and their effect on antioxidant activities in growing rice seedlings.

The synthesized α-MoO3 and MoS2 NPs had nanosheet and nanoflower-like structures with crystallite size of 21.34 nm and 4.32 nm, respectively. The uptake, bioaccumulation, and impact of these two Mo-NPs were studied in rice (Oryza sativa L) cv. HUR 3022 seedlings exposed to 100, 500, and 1000 ppm concentrations in hydroponics for 10 days in the growth medium. The uptake of α-MoO3 and MoS2 NPs by rice exposed to 100 ppm concentrations of NPs led to the accumulation of 7.32 ppm/4.55 ppm and 1.84 ppm/1.19 ppm in roots/shoots, respectively, as compared to controls. Unlike MoO3, more accumulation of MoS2 in roots reflect less translocation of this NP from roots to shoots. Results suggest tissue-specific distribution of NPs in rice seedlings. The increased growth and elevated protein levels in rice seedlings at 100 ppm concentrations of nanoparticles imply a stimulation in the repair mechanism at low doses indicating hormesis. MoS2 NPs treatments led to increased chlorophyll a levels suggesting it to be non-compromising with photosynthetic process in rice. The high malondialdehyde levels and altered activities of antioxidant enzymes GPX, APX, and CAT in rice seedlings exposed to α-MoO3 or MoS2 NPs indicate oxidative imbalance. Between α-MoO3 and MoS2 NPs, the former shows toxic effects as reflected from the decreased levels of photosynthetic pigments at all concentrations; however, an activation of chloroplast ROS detoxification is evident in the presence of MoS2 NPs. The BCF > 1 for both α-MoO3 and MoS2 NPs and TF of 0.6-2.0 and 0.42-0.65 suggest the latter to be more environmentally safe. In conclusion, a100 ppm MoS2 NPs concentration has low translocation and less accumulation with no significant impact on growth of rice cv. HUR 3022 seedlings and appears to be environmentally safe for future applications.

Glutathione improves rice tolerance to submergence: insights into its physiological and biochemical mechanisms

Complete submergence (Sub) imposes detrimental effects on growth and survival of crop plants, including rice. Here, we investigated the beneficial effects of reduced glutathione (GSH) in mitigating Sub-induced adverse effects in two high-yielding rice cultivars BRRI dhan29 and dhan52. Both cultivars experienced growth defects, severe yellowing, necrosis and chlorosis, when they were completely immersed in water for 14 days. The poor growth performance of these cultivars was linked to biomass reduction, decreased levels of photosynthetic pigments and proline, increased levels of H2O2 and malondialdehyde, and declined activities of enzymatic antioxidants like superoxide dismutase, ascorbate peroxidase, peroxidase, catalase, glutathione peroxidase and glutathione S-transferase. Pretreatment with exogenous GSH led to significant growth restoration in both cultivars exposed to Sub. The elevated Sub-tolerance promoted by GSH could partly be attributed to increased levels of chlorophylls, carotenoids, soluble proteins and proline. Exogenous GSH also mitigated Sub-induced oxidative damage, as evidenced from reduced levels of H2O2 and malondialdehyde in accordance with the increased activities of antioxidant enzymes. Results revealed that dhan52 was more tolerant to Sub-stress than dhan29, and GSH successfully rescued both cultivars from the damage of Sub-stress. Collectively, our findings provided an insight into the GSH-mediated active recovery of rice from Sub-stress, thereby suggesting that external supply of GSH may be an effective strategy to mitigate the adverse effects of Sub in rice.

Micropropagation of Atropa acuminata Royle ex Lindl. (a critically endangered medicinal herb) through root callus and evaluation of genetic fidelity, enzymatic and non-enzymatic antioxidant activity of regenerants

Atropa acuminata Royle ex Lindl. (family Solanaceae) is a critically endangered therapeutic herb, known for its immense therapeutic potential against innumerable ailments. In view of protecting this species from brink of extinction, present work focuses upon development of an effectual micropropagation protocol via indirect organogenesis using root-derived callus. Best callusing was observed on Murashige and Skoog (MS) medium augmented with 10 µM Thidiazuron (TDZ), where 99% of root explants induced whitish-green and compact calluses within 45 days. Upon sub-culturing on same medium (10 µM TDZ), these callus pieces differentiated an average of 5.54 ± 0.65 shoots having 2.38 ± 0.37 cm of length in 71.5% of the explants, after 28 days. MS + 1 µM indole-3-butyric acid (IBA) resulted in optimum rooting response where an average of 8.08 ± 0.19 roots having an average length of 7.28 ± 0.11 cm were produced. Micropropagated plants with well-developed and thick roots were acclimatized under greenhouse conditions. Genetic fidelity of ex vitro acclimatized plants using start codon targeted (SCoT) and sequence-related amplified polymorphism (SRAP) markers, revealed 96% similarity between mother plant and micropropagated plants. These plants showed higher yield of phenols, flavonoids and exhibited better antioxidant (DPPH and phosphomolybdenum assay) activities in comparison with mother plant. Higher levels of photosynthetic pigments and antioxidant enzymes were also observed in these plants as compared to the mother plant. Besides, quantification of atropine and scopolamine using high-performance liquid chromatography (HPLC) in different plant parts of acclimatized plantlets revealed higher amount of both the alkaloids in leaves. The present protocol shall be gainfully employed for large-scale micropropagation, conservation and extraction of biotherapeutic molecules for commercial purposes.

Dopamine Alleviates Hydrocarbon Stress in Brassica oleracea through Modulation of Physio-Biochemical Attributes and Antioxidant Defense Systems

Hydrocarbon stress has become one of the most restrictive factors for crop choice and productivity in most parts of the world. Dopamine (DA) has positively influenced the metabolic, physiological and biochemical activities besides the growth of plants under numerous abiotic stress conditions. The current study was performed to analyze the potential of DA to alleviate hydrocarbon stress and improve growth of Brassica oleracea plants. Hydrocarbon stress in plants was induced by growing in 5% and 10% crude oil contaminated soil. Crude oil stressed plants exhibited reduced growth besides decreased level of photosynthetic pigments and gas exchange attributes. Moreover, oil stressed plants showed elevated level of hydrogen peroxide (H2O2), electrolyte leakage (EL), malondialdehyde (MDA) and superoxide radical (O2−). However, exogenous application of 50, 100 and 200 μmol L−1 DA improved photosynthesis, shoot and root dry weight of B. oleracea seedlings growing in hydrocarbon amended soil. Additionally, DA100 treatments improved non-enzymatic and enzymatic antioxidants of treated seedlings. Our results demonstrate that increased gas exchange attributes, modulation of osmoregulators and improved activity of the antioxidative enzymes alleviated hydrocarbon stress in DA supplemented B. oleracea plants. Consequently, the first time observed ameliorative role of DA in hydrocarbon stress opens a new arena for application of this dynamic biomolecule for sustainable crop production.

Nitric oxide induced Cd tolerance and phytoremediation potential of B. juncea by the modulation of antioxidant defense system and ROS detoxification.

The present study designed to illustrate correlation between cadmium induced stress and plant growth, photosynthetic pigments, morphological and physiological attributes. To study these parameters 2 weeks old seedling of B. juncea were subjected to 50µM Cd, 100µM Cd and 100µM SNP separately and in combination with SNP. After 96h, the treated plant were harvested to analyze the cellular homeostasis and metal tolerance mechanism via examining growth, stress parameters, enzymatic and non enzymatic antioxidants and expression level of NR. Higher level of Cd (100µM) significantly increased accumulation of reactive oxygen species and malonaldehyde content in comparison to 50µM Cd. Exogenous supplementation of SNP (100µM) to 50µM Cd treated plant had an additive effect on plant growth by improving the level of proline, photosynthetic pigments and activities of enzymatic antioxidants which was confirmed by histochemical staining for NADPH-d and NO fluorescence from DAF-DA staining in roots of B. juncea. Applying SNP to 50µM Cd exposed B. juncea roots enhanced NR activity by 1.36 folds and increased NO production by 1.12 folds than individual Cd treated roots. In addition, semi quantitative RT-PCR study revealed the induction of BjNR was more pronounced in 50µM Cd treated roots in comparison to 100µM Cd treated roots. The present finding revealed NO confers increased B. juncea tolerance to Cd stress by stimulation of antioxidants and reestablishment of cellular redox status. Different biochemical analysis showed that plant growth, photosynthetic pigment and antioxidants were positively correlated with NO and it's negatively correlated with oxidative stress biomarkers. Therefore, NO is gaseous signalling molecule with potential role in Cd detoxification mechanism in B. juncea.

Application of seismo-mechanical stress in attenuation of in vitro induced abnormalities in Scaevola taccada (Gaertn.) Roxb.

Abstract Seismic stress interplayed in the alleviation of in vitro induced morphometric and biochemical disorders and effective acclimatization of plantlets of Scaevola taccada. The in vitro regenerated plantlets (through somatic embryogenesis) were subjected to various levels of seismo-mechanical agitations in the present study. The stress treatment at 100 rpm for 8 min increased the rate of shoot proliferation (43.3 shoots with 7.9 cm length), leaf area (2.0 cm × 1.4 cm), rhizogenesis (22.0 roots with 4.6 cm length), and plantlet biomass (480.0 mg fresh weight) as compared with the control (untreated) plantlets. Seismic stress also increased the level of photosynthetic pigments (chlorophyll a, b and carotenoids), total soluble sugars (TSS), total reducing sugars (TRS), and free amino acids (free AA) contents in the somatic embryo-derived plantlets. The deliberate seismic stress treatment for 4 wk significantly alleviated the in vitro induced morphological and biochemical aberrations to cope with the stress environment. Additionally, the treated plantlets responded better in acclimatization procedures with increased growth, yield, and survival rate (100%). The start codon targeted (SCoT) polymorphism analysis revealed that the plantlets regenerated through the seismo-mechanical stimulation exhibited genetic homogeneity with the mother plant.

Frond Optical Properties of the Fern Phyllitis scolopendrium Depend on Light Conditions in the Habitat.

Ferns display an elevated degree of phenotypic plasticity to changes in irradiance levels; however, only a few reports deal with their response to different light conditions. To get an insight into the extent of phenotypic plasticity of the fern Phyllitis scolopendrium, thriving in a forested area along a radiation gradient at the entrance of a cave, we examined selected biochemical, morphological, and physiological frond traits of the ferns from three different habitats. Sampling was performed two times during the vegetation season, in April and June. We also measured frond optical properties to point out the differences in leaf/light interactions between different plant samples. According to frond size, the middle habitat, receiving 125 µmol m−2s−1 of photosynthetically active radiation at both sampling times, appeared to be the most favourable. The production of UV-absorbing substances was highest in the habitat with the lowest radiation level. At the beginning of the season, the level of photosynthetic pigments in this habitat was the same as in the other habitats, while it was significantly lower in June when the tree canopy was closed. Frond reflectance was similar when comparing habitats and different sampling times. The most significant differences were obtained in the UV-A and near-infrared regions. The reflectance spectra depended mainly on frond biochemical properties, which altogether explained 54% (p ≤ 0.05) of the spectra variability. Frond transmittance depended on both, morphological parameters, explaining 51% (p ≤ 0.05), and frond biochemistry, explaining 73% (p ≤ 0.05) of the spectra variability. P. scolopendrium was revealed to be highly plastic regarding light conditions. The shapes of the frond reflectance and transmittance optical curves were similar to those typical of leaves of seed plants. The fronds exhibited high morphological plasticity when comparing different habitats. However, their biochemical and optical traits differed more between the two sampling times than between the habitats.