Measurement of the Light Intensity and Spectrum Influence on Plant Growth and Secondary Metabolites of Common Buckwheat.

Light is one of the main signals detected by plants that influence plant growth, development, and function. The light features that influence plants are the photoperiod, light intensity, and spectral composition. Manipulating light intensity and spectrum to obtain better plant growth and quality has become a popular research object in recent years. Here we describe the usage of the spectrometer Lighting Passport Pro to determine the impact of light intensity and share of individual waves in its spectrum in environment-controlled plant production systems on the growth, development, and soluble carbohydrate and phenolic synthesis of common buckwheat.

Chemical Composition and Bioactivity of Laboratory-Fermented Bee Pollen in Comparison with Natural Bee Bread.

Bee bread is a valuable product obtained from the hive on a relatively small scale, while bee pollen is more easily available. Therefore, an effective laboratory method of converting pollen into a bee bread substitute is desired. The aim of the research was to verify the influence of selected factors (temperature, ultrasound) on the quality of obtained product using Lactobacillus rhamnosus inoculum. The composition of the fermented pollen was analyzed using Inductively Coupled Plasma Optical Emission Spectroscopy (ICP-OES), Raman spectroscopy, and SDS-PAGE and compared to natural bee bread and the original pollen. In vitro biological activity was assessed as antioxidant activity using a yeast model (BY4741 and sod1∆ strains). Fermentation of pollen occurred spontaneously and after inoculation, as demonstrated by lower pH and higher lactic acid content. Raman spectroscopy and ICP-OES confirmed changes in composition compared to the initial pollen. Compared to bee bread, the fermented pollen showed a higher content of polyphenols and comparable antioxidant activity; moreover, it accelerated yeast growth rate. In addition, a protective effect was observed for Cu/Zn-superoxide dismutase 1 (sod1∆ yeast mutant exposed to hydrogen peroxide-induced oxidative stress). The higher fermentation temperature (25 °C) produces a more bee-bread-like product, while the use of ultrasound and starter culture seems to have no positive effect.

Application of Spectroscopic Methods for the Identification of Superoxide Dismutases in Cyanobacteria.

Superoxide dismutases (SODs) belong to the group of metalloenzymes that remove superoxide anion radicals and they have been identified in three domains of life: Bacteria, Archaea and Eucarya. SODs in Synechocystis sp. PCC 6803, Gloeobacter violaceus CCALA 979, and Geitlerinema sp. ZHR1A were investigated. We hypothesized that iron (FeSOD) and/or manganese (MnSOD) dominate as active forms in these cyanobacteria. Activity staining and three different spectroscopic methods of SOD activity bands excised from the gels were used to identify a suitable metal in the separated samples. FeSODs or enzymes belonging to the Fe-MnSOD superfamily were detected. The spectroscopic analyses showed that only Fe is present in the SOD activity bands. We found FeSOD in Synechocystis sp. PCC 6803 while two forms in G. violaceus and Geitlerinema sp. ZHR1A: FeSOD1 and FeSOD2 were present. However, no active Cu/ZnSODs were identified in G. violaceus and Geitlerinema sp. ZHR1A. We have shown that selected spectroscopic techniques can be complementary to the commonly used method of staining for SOD activity in a gel. Furthermore, the occurrence of active SODs in the cyanobacteria studied is also discussed in the context of SOD evolution in oxyphotrophs.

Photosynthetic efficiency, growth and secondary metabolism of common buckwheat (Fagopyrum esculentum Moench) in different controlled-environment production systems.

Light-emitting diodes (LEDs) and high-pressure sodium lamps (HPS) are among the most commonly used light sources for plant cultivation. The objective of this study was to evaluate the effect of two controlled-environment production systems differing in light sources on growth, photosynthetic activity, and secondary metabolism of common buckwheat. We hypothesized that LED light with the majority of red and blue waves would increase physiological and biochemical parameters compared to sunlight supplemented with HPS lamps. The experiment was performed in a phytotronic chamber (LEDs) and in a greenhouse (solar radiation supplemented with HPS lamps as a control). The effects were analyzed at the flowering phase with biometric measurements, leaf chlorophyll index, the kinetics of chlorophyll a fluorescence, content of soluble carbohydrates and phenolics in the leaves. Applied LED light decreased the biomass but stimulated the production of phenolics compared to control plants. In control plants, a positive correlation between flavonoid content and energy dissipation from photosystem II (DIo/CSm) was found, while in plants under LEDs total pool of phenolic content correlated with this parameter and the quantum yield of electron transport (φ Ro and ψ Ro) was lower than that of the control, probably affecting buckwheat biomass.

Insight into Details of the Photosynthetic Light Reactions and Selected Metabolic Changes in Tomato Seedlings Growing under Various Light Spectra.

The objective of our study was to characterise the growth of tomato seedlings under various light spectra, but special attention has been paid to gaining a deeper insight into the details of photosynthetic light reactions. The following light combinations (generated by LEDs, constant light intensity at 300 µmol m-2 s-1) were used: blue/red light; blue/red light + far red; blue/red light + UV; white light that was supplemented with green, and white light that was supplemented with blue. Moreover, two combinations of white light for which the light intensity was changed by imitating the sunrise, sunset, and moon were also tested. The reference point was also light generated by high pressure sodium lamps (HPS). Plant growth/morphological parameters under various light conditions were only partly correlated with the photosynthetic efficiency of PSI and PSII. Illumination with blue/red as the main components had a negative effect on the functioning of PSII compared to the white light and HPS-generated light. On the other hand, the functioning of PSI was especially negatively affected under the blue/red light that was supplemented with FR. The FT-Raman studies showed that the general metabolic profile of the leaves (especially proteins and ß-carotene) was similar in the plants that were grown under the HPS and under the LED-generated white light for which the light intensity changed during a day. The effect of various light conditions on the leaf hormonal balance (auxins, brassinosteroids) is also discussed.