Plastics enter in terrestrial natural system primarily by agricultural purposes, while acid rain is the result of anthropogenic activities. The synergistic effects of microplastics and acid rain on ...plant growth are not known. In this study, different sizes of polyethylene terephthalate (PET) and acid rain are tested on Lepidium sativum, in two separate experimental sets. In the first one we treated plants only with PET, in the second one we used PET and acid rain together. In both experimentations we analyzed: i) plant biometrical parameters (shoot height, leaf number, percentage inhibition of seed germination, fresh biomass), and ii) oxidative stress responses (hydrogen peroxide; ascorbic acid and glutathione). Results carried out from our experiments highlighted that different sizes of polyethylene terephthalate are able to affect plant growth and physiological responses, with or without acid rain supplied during acute toxicity (6 days).
This study showed that different sizes of PET microplastics affect physiological and biometrical responses of Lepidum sativum seedlings, with or without acid rain; roots and leaves responded differently.
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•PETs microplastics are tested on L. sativum under natural and acidified conditions.•Significant effects on biometry and physiology of tested plant are recorded.•The contextual exposure to PET and acid rains conditions affected shoots.•Roots are more strongly affected by the particle size of PET than by acid rains.
Seed germination is an important life-cycle transition because it determines subsequent plant survival and reproductive success. To detect optimal spatiotemporal conditions for germination, seeds act ...as sophisticated environmental sensors integrating information such as ambient temperature. Here we show that the DELAY OF GERMINATION 1 (DOG1) gene, known for providing dormancy adaptation to distinct environments, determines the optimal temperature for seed germination. By reciprocal gene-swapping experiments between Brassicaceae species we show that the DOG1-mediated dormancy mechanism is conserved. Biomechanical analyses show that this mechanism regulates the material properties of the endosperm, a seed tissue layer acting as germination barrier to control coat dormancy. We found that DOG1 inhibits the expression of gibberellin (GA)-regulated genes encoding cell-wall remodeling proteins in a temperature-dependent manner. Furthermore we demonstrate that DOG1 causes temperature-dependent alterations in the seed GA metabolism. These alterations in hormone metabolism are brought about by the temperature-dependent differential expression of genes encoding key enzymes of the GA biosynthetic pathway. These effects of DOG1 lead to a temperature-dependent control of endosperm weakening and determine the optimal temperature for germination. The conserved DOG1-mediated coat-dormancy mechanism provides a highly adaptable temperature-sensing mechanism to control the timing of germination.
Metal contamination of soils has become a worldwide problem and great environmental threat, as these metals accumulate in soils and plants in excess, and enter the food chain. Increased cadmium (Cd) ...uptake from contaminated soils leads to altered plant metabolism and limits the crop productivity. The experimental crop,
Lepidium sativum L. (Garden Cress, Family: Brassicaceae) is a medicinally and economically important plant. An experiment was conducted to examine the effect of different concentrations of Cd (0, 25, 50 or 100
mg
kg
−1 soil) on the performance of
L.
sativum. Cd accumulation in roots and leaves (roots
>
leaves) increased with the increaseing Cd concentration in soil. High Cd concentration (100
mg Cd kg
−1 soil) inhibited the leaf area and plant dry mass and significant decline in net photosynthetic rate (
P
N), stomatal conductance (gs), intercellular CO
2 (C
i), chlorophyll (Chl a, Chl b, total Chl) content, carbonic anhydrase (CA; E.C. 4.2.1.1) activity, nitrate reductase (NR; E.C. 1.6.6.1) activity and nitrogen (N) content was also observed. However, ATP-sulfurylase (ATP-S; EC. 2.7.7.4) activity, sulfur (S) content and activities of antioxidant enzymes such as superoxide dismutase (SOD; E.C. 1.15.1.1); catalase (CAT; E.C. 1.11.1.6); ascorbate peroxidase (APX; E.C. 1.11.1.11) and glutathione reductase (GR; E.C. 1.6.4.2) and glutathione (GSH) content were increased. Specifically, the decrease in NR activity and N content showed that Cd affects N metabolism negatively; whereas, the increase in ATP-S activity and S content suggests the up-regulation of S assimilation pathway for possible Cd tolerance in coordination with enhanced activities of antioxidant enzymes and GSH. High Cd concentration (100
mg Cd kg
−1 soil) perturbs the
L.
sativum growth by interfering with the photosynthetic machinery and disrupting the coordination between carbon, N and S metabolism. On the other hand, at low Cd concentration (25
mg Cd kg
−1 soil) co-ordination of S and N metabolism complemented to the antioxidant machinery to protect the growth and photosynthesis of
L.
sativum plants.
Germination of endospermic seeds is partly regulated by the micropylar endosperm, which acts as constraint to radicle protrusion. Gibberellin (GA) signalling pathways control coat-dormancy release, ...endosperm weakening, and organ expansion during seed germination. Three GIBBERELLIN INSENSITIVE DWARF1 (GID1) GA receptors are known in Arabidopsis thaliana: GID1a, GID1b, and GID1c. Molecular phylogenetic analysis of angiosperm GID1s reveals that they cluster into two eudicot (GID1ac, GID1b) groups and one monocot group. Eudicots have at least one gene from each of the two groups, indicating that the different GID1 receptors fulfil distinct roles during plant development. A comparative Brassicaceae approach was used, in which gid1 mutant and whole-seed transcript analyses in Arabidopsis were combined with seed-tissue-specific analyses of its close relative Lepidium sativum (garden cress), for which three GID1 orthologues were cloned. GA signalling via the GID1ac receptors is required for Arabidopsis seed germination, GID1b cannot compensate for the impaired germination of the gid1agid1c mutant. Transcript expression patterns differed temporarily, spatially, and hormonally, with GID1b being distinct from GID1ac in both species. Endosperm weakening is mediated, at least in part, through GA-induced genes encoding cell-wall-modifying proteins. A suppression subtraction hybridization (SSH) cDNA library enriched for sequences that are highly expressed during early germination in the micropylar endosperm contained expansins and xyloglucan endotransglycosylases/hydrolases (XTHs). Their transcript expression patterns in both species strongly suggest that they are regulated by distinct GID1-mediated GA signalling pathways. The GID1ac and GID1b pathways seem to fulfil distinct regulatory roles during Brassicaceae seed germination and seem to control their downstream targets distinctly.
•SFE as efficient method of flavonoids extraction from freeze-dried sprouts.•The best antibacterial activity the SFE extract from freeze-fried sprouts.•SFE of dried Lepidium sativum sprouts is ...efficient in extraction of isothiocyanates.•Water as efficient solvent for extraction of polyphenols from L. sativum seeds.
The aim of this study was to evaluate chemical and biological potential of garden cress (Lepidium sativum L.) to receive valuable plant extracts with potential application in pharmacy or food industry. Four techniques of extraction and three environmentally friendly solvents such as water, supercritical CO2 and ethanol have been tested. Biological activity and chemical profile were evaluated in obtained extracts. GC/MS analysis showed that SFE extract from dried sprouts of L. sativum was especially rich in such glucosinolate derivatives as benzyl cyanide and benzyl thiocyanate. However, the extract obtained from freeze-dried sprouts by SFE with addition of 96% ethanol as co-solvent was especially rich in flavonoids and simultaneously exhibited the best antimicrobial activity. Comparison of MALDI-TOF-MS spectra of all obtained extracts clearly indicates that both SFE and maceration with water are the most selective techniques of extraction due to the lowest level of interfering substances with high molecular masses.
The main objective of this work is to evaluate the phytotoxicity of olive mill solid wastes (OMW) produced in two different centrifugation technologies and also the toxicity associated with specific ...phenolic compounds. Two samples of waste were collected in two-phase (2P-OMW) and three-phase (3P-OMW) centrifugation olive oil production processes, and cress bioassays with Lepidium sativum L. were employed to evaluate phytotoxicity. Although both OMW have similar total phenolic content (TPh), results confirmed that 2P-OMW is more phytotoxic than 3P-OMW. When extracts from 2P-OMW at liquid to solid ratio of 10 L kg−1 were applied none of the seeds germinated, i.e. germination index (GI) was 0%, while for 3P-OMW GI was 94.3%. Growth tests in soil and mixtures with OMW also led to more favorable results for 3P-OMW, whereas worse results than those obtained in the control experiments were observed.
In order to discriminate the individual influence of eleven phenolic compounds, gallic acid, protocatechuic acid, cinnamic acid, syringic acid, 3,4,5-trimethoxybenzoic acid, 4-hydroxybenzoic acid, vanillic acid, p-coumaric acid, caffeic acid, veratric acid and phenol were tested in the concentration range of 5–500 mg L−1. Results showed that cinnamic acid is the most phytotoxic, with EC50 of 60 mg L−1, which is related with its hydrophobicity. Moreover, increasing -OH and -OCH3 groups in these molecules seem to reduce phytotoxicity. Tests with a mixture of six phenolic compounds demonstrated there are neither synergistic nor additive effects. The phytotoxicity appears to be determined by the presence of the most lipophilic phenolic molecule.
•Phytotoxicity of olive mill solid wastes (OMSW) was evaluated with Lepidium sativum.•Phytotoxicity of OMSW was related with specific phenolic compounds.•Among the phenolic compounds, cinnamic acid revealed to be the most phytotoxic.•Lipophilic nature of phenolic compounds is associated with the phytotoxic activity.
Myrica gale L. (sweet gale) fruit leachate contains myrigalone A (MyA), a rare C-methylated dihydrochalcone and putative allelochemical, which is known to be a phytotoxin impeding seedling growth. We ...found that MyA inhibited Lepidium sativum L. seed germination in a dose-dependent manner. MyA did not affect testa rupture, but inhibited endosperm rupture and the transition to subsequent seedling growth. MyA inhibited micropylar endosperm cap (CAP) weakening and the increase in the growth potential of the radical/hypocotyl region (RAD) of the embryo, both being key processes required for endosperm rupture. We compared the contents of abscisic acid (ABA) and gibberellins in the tissues and found that the major bioactive forms of gibberellin in L. sativum seed tissues were GA4 and GA6, while GA8 and GA13 were abundant inactive metabolites. MyA did not appreciably affect the ABA contents, but severely interfered with gibberellin metabolism and signaling by inhibiting important steps catalyzed by GA3 oxidase, as well as by interfering with the GID1-type gibberellin signaling pathway. The hormonally and developmentally regulated formation of apoplastic superoxide radicals is important for embryo growth. Specific zones within the RAD were associated with accumulation of apoplastic superoxide radicals and endoreduplication indicative of embryo cell extension. MyA negatively affected both of these processes and acted as a scavenger of apoplastic reactive oxygen species. We propose that MyA is an allelochemical with a novel mode of action on seed germination.
The impacts of nano- and microplastics (<100 nm and <5 mm, respectively) on terrestrial systems is to the present largely unexplored. Plastic particles are likely to accumulate in these systems ...primarily by the application of sewage sludge. The aim of the current study was to investigate the effects of three sizes of plastic particles (50, 500, and 4800 nm) on a terrestrial plant (cress; Lepidium sativum), using a standardized 72 h bioassay. Cress seeds were exposed to five different concentrations of plastics, ranging from 103 to 107 particles mL−1. Germination rate was significantly reduced after 8 h of exposure for all three sizes of plastics, with increased adverse effect with increasing plastic sizes. Seeds exposed to 4800 nm microplastics showed a germination rate decline from 78% in control to 17% in the highest exposure. No difference in germination rate occurred after 24 h of exposure, regardless of the size of the plastic used. Significant differences in root growth were observed after 24 h, but not after 48 or 72 h of exposure. Impacts on germination are likely due to physical blockage of the pores in the seed capsule by microplastics as shown by confocal microscopy of fluorescent microplastics. In later stages, the microplastics particularly accumulated on the root hairs. This is the first detailed study on the effect of nano- and microplastics on a vascular, terrestrial plant, and our results indicate short-term and transient adverse effects.
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•Terrestrial systems accumulate nano- and microplastics but are understudied.•We exposed a vascular plant to three different sized plastics (50, 500 and 4800 nm).•Exposure to plastics caused significant impacts on germination and root growth.•Late germination is likely related to accumulation of microplastics on seed case.•The observed effects were short-term and transient.
Aims
This study aims to evaluate the impact of solid‐state fermentation (SSF) by Trichoderma reesei on the phenolic content, antioxidant and antimicrobial activities of garden cress seeds (GCS).
...Methods and Results
The factorial statistical design was employed to optimize the SSF conditions, incubation time, pH, temperature and moisture, for maximum production of the phenolic content and microbial carbohydrate‐cleaving enzymes from GCS. The total phenolic content significantly increased from unfermented GCS (401 mg gallic acid equivalent (GAE) 100 g−1) to fermented GCS (3600 mg GAE 100 g−1) by ninefold. The total antioxidant activity significantly increased in fermented GCS. Fifteen phenolic compounds were detected in fermented GCS with high concentrations compared to 14 in unfermented GCS using high‐performance liquid chromatography. A strong correlation between the production of the carbohydrate‐cleaving enzymes and the phenolic content of fermented GCS was observed. The phenolic compounds of fermented GCS showed higher antimicrobial activity.
Conclusions
The fermented GCS is a powerful source of phenolic compounds with high antioxidant potentials, which can be used as dietary supplement and antimicrobial agent.
Significance and Impact of the Study
Solid‐state fermentation is a promising technique used for production of added‐value bioactive compounds. SSF increased the total phenolic content and antioxidant activity of GCS several folds compared to germination process, which recently studied.
Extremely high organic load and the toxic nature of olive mill wastewater (OMW) prevent their direct discharge into domestic wastewater treatment systems. In addition to the various treatment schemes ...designed for such wastewater, controlled land spreading of untreated OMW has been suggested as an alternative mean of disposal. A field study was conducted between October 2004 and September 2005 to assess possible effects of OMW on soil microbial activity and potential phytotoxicity. The experiment was carried out in an organic orchard located on a Vertisol-type soil (Jezre’el Valley, Israel) and included two application levels of OMW (36 and 72
m
3
ha
−1). Total microbial counts, and to less extent the hydrolytic activity and soil respiration were increased following the high OMW application level. A bench-scale lab experiment showed that the rate of OMW mineralization was mainly dependent on the general status of soil activity and was not related to previous acclimatization of the soil microflora to OMW. Soil phytotoxicity (% germination and root elongation) was assessed in soil extracts of samples collected before and after each OMW application, using germinating cress (
Lepidium sativum L.) seeds. We found direct short-term effect of OMW application on soil phytotoxicity. However, the soil was partly or completely recovered between successive applications. No further phytotoxicity was observed in treated soils as compared with control soil, 3 months after OMW application. Such short-term phytotoxicity was not in correlation with measured EC and total polyphenols in the soil extracts. Overall, the results of this study further support a safe controlled OMW spreading on lands that are not associated with sensitive aquifers.
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