Nedeštrukčná detekcia a biochemická kvantifikácia listov pohánky s využitím hyperspektrálneho zobrazovania s reflektanciou vo viditeľnej (VIS) a blízkej infračervenej (NIR) oblasti

The present experimental study has been investigated way of use methodology of nondestructive detection with hyperspectral reflectance imaging together with wet chemistry quantitative analysis based on correlation analysis of receiving data. Higher correlation from reflectance of hyperspectral imaging analysis and total polyphenol and anthocyanin content has been observed for carotenoid reflectance index-2 compared to the carotenoid reflectance index-1. It was found that high total polyphenols content is related with high values of hyperspectral indices which characterize chlorophyll concentration and parameters of vegetation. In experimental buckwheat cultivars presence of vanillic, methoxycinnamic, cinnamic acids can be expressing by anthocyanin reflectance index, modified anthocyanin reflectance index and carotenoid reflectance index-2 because high correlation coefficient. Changes of chlorogenic acid during the vegetative period of plant growth can be studied with normalized difference vegetation index and normalized difference vegetation index-2 which found to have a positive correlation with this phenolic acid content.Predkladaná experimentálna práca skúmala možnosti uplatnenia metodológie nedeštrukčnej detekcie s hyperspektrálnym reflektančným zobrazovaním spolu s kvantitatívnou chemickou analýzou na základe korelačnej analýzy získaných údajov. V porovnaní s karotenoidovým reflektančným indexom-1 bola vyššia korelácia s obsahom celkových polyfenolov a celkových antokyánov pozorovaná s reflektanciou karotenoidového reflektančného indexu-2 z analýzy hyperspektrálneho zobrazovania. Vysoký obsah celkových polyfenolov súvisel s vysokými hodnotami hyperspektrálnych indexov charakterizujúcich koncentráciu chlorofylu a parametre vegetácie. V experimentálnych kultivaroch pohánky môže byť prítomnosť kyseliny vanilovej, metoxyškoricovej a škoricovej, vzhľadom k vysokému korelačnému koeficientu, vyjadrená pomocou antokyánového reflektančného indexu, modifikovaného antokyánového reflektančného indexu a karotenoidového reflektančného indexu-2. Zmeny obsahu kyseliny chlorogénovej počas vegetačného obdobia pohánky môžu byť sledované prostredníctvom normalizovaného diferenčného vegetačného indexu a diferenčného vegetačného indexu-2, ktoré preukázali pozitívnu koreláciu s obsahom fenolových kyselín

Increased photosynthesis from a deep-shade to high-light regime occurs by enhanced CO2 diffusion into the leaf of Selaginella martensii

The current understanding of photosynthesis across land plant phylogeny strongly indicates that ancient vascular plants are mainly limited by strong constitutive CO2 diffusional constraints, particularly low stomatal and mesophyll conductance. Considering that the lycophyte Selaginella martensii can demonstrate long-term light acclimation, this study addresses the regulation extent of CO2 assimilation in this species cultivated under contrasting light regimes of deep shade, medium shade and high light. Comparative analyses of photosynthetic traits, CO2 conductance and leaf morpho-anatomy revealed acclimation plasticity similar to that of seed plants, though occurring in the context of an inherently low photosynthetic capacity typical of lycophytes. Specific modulations of the stomatal density and aperture, chloroplast surface exposed to mesophyll airspaces and cell wall thickness sustained a marked improvement in CO2 diffusion from deep shade to high light. However, the maximum carboxylation rate was comparatively less effectively upregulated, leading to a greater incidence of biochemical limitations of photosynthesis. Because of a low carboxylation capacity under any light regime, a lycophyte prevents potential photodamage to the chloroplast by not only exploiting the thermal dissipation of excess absorbed energy but also diverting a large fraction of photosynthetic electrons to sinks alternative to carboxylation

Diversity of Leaf Cuticular Transpiration and Growth Traits in Field-Grown Wheat and Aegilops Genetic Resources

Plants are subjected to unregulated water loss from their surface by cuticular transpiration. Therefore, specific morphophysiological changes may occur during leaf development to eliminate water loss. This study aimed to examine the cuticular transpiration of 23 winter wheat genotypes and their wild-growing predecessors of the genus Aegilops, which were divided into three groups to demonstrate their diversity. The genotypes were sown in autumn and grown in regular field trials at the Research Institute of Plant Production in Piešťany, Slovakia. Cuticular transpiration and growth parameters were analyzed in the postanthesis growth stage. Gravimetric measurement of residual water loss was performed on detached leaves with a precisely measured leaf area. The lowest nonproductive transpiration values were observed in modern wheat genotypes, while higher cuticular transpiration was observed in a group of landraces. Aegilops species generally showed the highest cuticular transpiration with increased water loss, but the total water loss per plot was low due to the low leaf area of the wild wheat relatives. Some of the growth parameters showed a good correlation with cuticular transpiration (e.g., dry mass per plant), but direct relationships between leaf traits and cuticular transpiration were not observed. This study identified a high diversity in cuticular resistance to water loss in wheat and Aegilops accessions of different origins. The potential of identifying and exploiting genetic resources with favorable cuticular transpiration in crop breeding is discussed

Optimal Nitrogen Supply Ameliorates the Performance of Wheat Seedlings under Osmotic Stress in Genotype-Specific Manner

Strategies and coping mechanisms for stress tolerance under sub-optimal nutrition conditions could provide important guidelines for developing selection criteria in sustainable agriculture. Nitrogen (N) is one of the major nutrients limiting the growth and yield of crop plants, among which wheat is probably the most substantial to human diet worldwide. Physiological status and photosynthetic capacity of two contrasting wheat genotypes (old Slomer and modern semi-dwarf Enola) were evaluated at the seedling stage to assess how N supply affected osmotic stress tolerance and capacity of plants to survive drought periods. It was evident that higher N input in both varieties contributed to better performance under dehydration. The combination of lower N supply and water deprivation (osmotic stress induced by polyethylene glycol treatment) led to greater damage of the photosynthetic efficiency and a higher degree of oxidative stress than the individually applied stresses. The old wheat variety had better N assimilation efficiency, and it was also the one with better performance under N deficiency. However, when both N and water were deficient, the modern variety demonstrated better photosynthetic performance. It was concluded that different strategies for overcoming osmotic stress alone or in combination with low N could be attributed to differences in the genetic background. Better performance of the modern variety conceivably indicated that semi-dwarfing (Rht) alleles might have a beneficial effect in arid regions and N deficiency conditions

Pre-Acclimation to Elevated Temperature Stabilizes the Activity of Photosystem I in Wheat Plants Exposed to an Episode of Severe Heat Stress

The importance of high temperature as an environmental factor is growing in proportion to deepening global climate change. The study aims to evaluate the effects of long-term acclimation of plants to elevated temperature on the tolerance of their photosynthetic apparatus to heat stress. Three wheat (Triticum sp. L.) genotypes differing in leaf and photosynthetic traits were analyzed: Thesee, Roter Samtiger Kolbenweizen, and ANK 32A. The pot experiment was established in natural conditions outdoors (non-acclimated variant), from which a part of the plants was placed in foil tunnel with elevated temperature for 14 days (high temperature-acclimated variant). A severe heat stress screening experiment was induced by an exposition of the plans in a growth chamber with artificial light and air temperature up to 45 °C for ~12 h before the measurements. The measurements of leaf photosynthetic CO2 assimilation, stomatal conductance, and rapid kinetics of chlorophyll a fluorescence was performed. The results confirmed that a high temperature drastically reduced the photosynthetic assimilation rate caused by the non-stomatal (biochemical) limitation of photosynthetic processes. On the other hand, the chlorophyll fluorescence indicated only a moderate level of decrease of quantum efficiency of photosystem (PS) II (Fv/Fm parameter), indicating mostly reversible heat stress effects. The heat stress led to a decrease in the number of active PS II reaction centers (RC/ABS) and overall activity o PSII (PIabs) in all genotypes, whereas the PS I (parameter ψREo) was negatively influenced by heat stress in the non-acclimated variant only. Our results showed that the genotypes differ in acclimation capacity to heat stress, and rapid noninvasive techniques may help screen the stress effects and identify more tolerant crop genotypes. The acclimation was demonstrated more at the PS I level, which may be associated with the upregulation of alternative photosynthetic electron transport pathways with clearly protective functions

Antioxidant, Antiproliferative and Apoptosis-Inducing Efficacy of Fractions from Cassia fistula L. Leaves

Cassia fistula L. is a highly admirable traditional medicinal plant used for the treatment of various diseases and disorders. The present study was performed to divulge the antioxidant, antiproliferative, and apoptosis-inducing efficacy of fractions from C. fistula leaves. The hexane (CaLH fraction), chloroform (CaLC fraction), ethyl acetate (CaLE fraction), n-butanol (CaLB fraction), and aqueous (CaLA fraction) were sequentially fractionated from 80% methanolic (CaLM extract) of C. fistula leaves. The CaLE fraction was fractionated using column chromatography to yield a pure compound, which was characterized as Epiafzelechin (CFL1) based on 1H, 13C, and DEPT135 NMR. Among these fractions, CaLE and isolated CFL1 fractions exhibited an effective antioxidant potential in Ferric ion reducing power, (2,2’-azino-bis (3-ethylbenzothiazoline -6-sulfonic acid)) cation radical scavenging, and nitric oxide radical scavenging assays. Epiafzelechin was investigated for its antiproliferative effects against MG-63 (osteosarcoma), IMR-32 (neuroblastoma), and PC-3 (prostate adenocarcinoma), and was found to inhibit cell proliferation with a GI50 value of 8.73, 9.15, and 11.8 μM respectively. MG-63 cells underwent apoptotic cell death on treatment with Epiafzelechin as the cells showed the formation of apoptotic bodies, enhanced reactive oxygen species (ROS) generation, mitochondrial membrane depolarization along with an increase in early apoptotic cell population analyzed using Annexin V-FITC/PI double staining assay. Cells showed cell cycle arrest at the G0/G1 phase accompanied by a downregulation in the expression levels of p-Akt (Protein kinase B), p-GSK-3β (Glycogen synthase kinase-3 beta), and Bcl-xl (B-cell lymphoma-extra large) proteins. RT-PCR (Real time-polymerase chain reaction) analysis revealed downregulation in the gene expression level of β-catenin and CDK2 (cyclin-dependent kinases-2) while it upregulated the expression level of caspase-8 and p53 genes in MG-63 cells

Melatonin Modulates Plant Tolerance to Heavy Metal Stress: Morphological Responses to Molecular Mechanisms

Heavy metal toxicity is one of the most devastating abiotic stresses. Heavy metals cause serious damage to plant growth and productivity, which is a major problem for sustainable agriculture. It adversely affects plant molecular physiology and biochemistry by generating osmotic stress, ionic imbalance, oxidative stress, membrane disorganization, cellular toxicity, and metabolic homeostasis. To improve and stimulate plant tolerance to heavy metal stress, the application of biostimulants can be an effective approach without threatening the ecosystem. Melatonin (N-acetyl-5-methoxytryptamine), a biostimulator, plant growth regulator, and antioxidant, promotes plant tolerance to heavy metal stress by improving redox and nutrient homeostasis, osmotic balance, and primary and secondary metabolism. It is important to perceive the complete and detailed regulatory mechanisms of exogenous and endogenous melatonin-mediated heavy metal-toxicity mitigation in plants to identify potential research gaps that should be addressed in the future. This review provides a novel insight to understand the multifunctional role of melatonin in reducing heavy metal stress and the underlying molecular mechanisms