Integrative Physiological and Transcriptome Analysis Reveals the Mechanism of Cd Tolerance in Sinapis alba

Recently, pollution caused by the heavy metal Cd has seriously affected the environment and agricultural crops. While Sinapis alba is known for its edible and medicinal value, its tolerance to Cd and molecular response mechanism remain unknown. This study aimed to analyze the tolerance of S. alba to Cd and investigate its molecular response mechanism through transcriptomic and physiological indicators. To achieve this, S. alba seedlings were treated with different concentrations of CdCl2 (0.25 mmol/L, 0.5 mmol/L, and 1.0 mmol/L) for three days. Based on seedling performance, S. alba exhibited some tolerance to a low concentration of Cd stress (0.25 mmol/L CdCl2) and a strong Cd accumulation ability in its roots. The activities and contents of several antioxidant enzymes generally exhibited an increase under the treatment of 0.25 mmol/L CdCl2 but decreased under the treatment of higher CdCl2 concentrations. In particular, the proline (Pro) content was extremely elevated under the 0.25 and 0.5 mmol/L CdCl2 treatments but sharply declined under the 1.0 mmol/L CdCl2 treatment, suggesting that Pro is involved in the tolerance of S. alba to low concentration of Cd stress. In addition, RNA sequencing was utilized to analyze the gene expression profiles of S. alba exposed to Cd (under the treatment of 0.25 mmol/L CdCl2). The results indicate that roots were more susceptible to disturbance from Cd stress, as evidenced by the detection of 542 differentially expressed genes (DEGs) in roots compared to only 37 DEGs in leaves. GO and KEGG analyses found that the DEGs induced by Cd stress were primarily enriched in metabolic pathways, plant hormone signal transduction, and the biosynthesis of secondary metabolites. The key pathway hub genes were mainly associated with intracellular ion transport and cell wall synthesis. These findings suggest that S. alba is tolerant to a degree of Cd stress, but is also susceptible to the toxic effects of Cd. Furthermore, these results provide a theoretical basis for understanding Cd tolerance in S. alba.

Trans-generational effect of cerium oxide-nanoparticles (nCeO2) on Chenopodium rubrum L. and Sinapis alba L. seeds

Cerium oxide nanoparticles (nCeO2 ) are interesting nanomaterials due to their redox properties. Their wide application could result in unexpected consequences to environmental safety. Unlike acute toxicity, the trans-generational effects of carbohydrate-coated nCeO2 in the environment are still unknown. The main aim of this study was to investigate the effect of treating maternal plants of Chenopodium rubrum L. (red goosefoot) and Sinapis alba L. (white mustard) with uncoated (CeO2 ) and glucose-, levan-, or pullulan-coated nCeO2 (G-, L-, or P-CeO2 ) during seed germination on morphological and physiological characteristics of produced seeds in two subsequent generations. The plant response was studied by measuring germination percentage (Ger), total protein content (TPC), total phenolic content (TPhC), total antioxidative activity (TAA), and catalase (CAT) activity. Results showed that maternal effects of the different nCeO2 treatments persist to at least the second generation in seeds. Generally, C. rubrum was more sensitive to nCeO2 treatments than S. alba . The coated nCeO2 were more effective than uncoated ones in both plant species; L- and P-CeO2 were the most effective in S. alba , while CeO2 and G-CeO2 had a dominant impact in C. rubrum . Enhanced germination in all tested generations of S. alba seeds recommends nCeO2 for seed priming.

Effects of white mustard (Sinapis alba) oil on growth performance, immune response, blood parameters, digestive and antioxidant enzyme activities in rainbow trout (Oncorhynchusmykiss)

A study was conducted to evaluate the effects of dietary supplementation of white mustard (Sinapis alba) oil (WMO) on growth performance, immune responses, digestive and antioxidant enzyme activities in juvenile rainbow trout (Oncorhynchus mykiss). For this purpose, fish (initial weight: 25.77 ± 0.13 g) were divided into four experimental groups in triplicate and fed ad libitum twice a day with diets containing WMO at 0 (control), 0.5, 1, and 1.5% of diet for 9 weeks. Three fish from each tank (n:9 per treatment) were sampled on 21st, 42nd, and 63rd days for further analyses. At the end of the feeding period, fish were challenged with Aeromonas hydrophila and Yersinia ruckeri in two separate experimental setups. Results showed that final weight, weight gain, and specific growth rate were significantly increased in all experimental groups compared to the control. Feed conversion ratio was similar among treatments. Respiratory burst and potential killing activity decreased in all experimental groups compared to the control (P < 0.05). Lysozyme and myeloperoxidase activities were elevated in all experimental groups at the end of the experiment compared to the control (P < 0.05). Cytokine gene expressions in the head kidney and intestine were elevated in all experimental groups compared to that of the control in general (P < 0.05). Hematological responses of the experimental fish groups were similar to that of the control (P > 0.05). Pepsin and trypsin levels decreased in all experimental groups (P < 0.05). In terms of antioxidant enzyme activities, significant improvement in liver superoxide dismutase, catalase, and glutathione s-transferase activities in all treatment groups were determined (P < 0.05). In addition, a significant decline in liver lipid peroxidation levels was recorded in all treated groups at all sampling times compared to the control (P < 0.05). At the end of this feeding trial, no significant differences (P > 0.05) were observed in survival against A. hydrophila among experimental groups compared to the control (P > 0.05). However, increased survival against Y. ruckeri was determined in experimental fish groups (P < 0.05). This study suggests that white mustard oil had a favorable effect on the overall health and growth of rainbow trout.

Effects of sewage sludge supplementation on heavy metal accumulation and the expression of ABC transporters in Sinapis alba L. during assisted phytoremediation of contaminated sites

ATP binding cassette (ABC) transporters, types C, G, and B were monitored via qPCR in order to investigate the influence of heavy metal (HM) contamination of post-industrial and post-agricultural soils and the effects of its supplementation with sewage sludge, on Sinapis alba plants. Five house-keeping genes were selected and validated to ensure the best reference points. The relative expression of ABC types C and G genes was profoundly affected by experimental conditions and included their upregulation after plants exposure to heavy metals and downregulation after supplementation with sewage sludge. However, ABC type C was more responsive then type G. The experimental conditions altered the expression of ABC type C gene faster than ABC type G and thus, the expression of ABC type C can therefore potentially be used as a bioindicator during assisted phytoremediation of degraded sites. In clean soil, supplementation with sewage sludge with a slight content of heavy metals still caused an upregulation in the expression of ABC types C and G, which showed that proper toxicity assessments are necessary to ensure safe application of sewage sludge into soils. Results showed that the analysed genes take a significant part in plants metal detoxification and that their expression is regulated at transcriptional level after exposure to soil contaminated with heavy metals by both, industrial activities and by sewage sludge supplementation. Thus, their expression can potentially be used as an early-warning biomarker when soil supplementation with sewage sludge is incorporated into the soil-management process.

Detail investigation of toxicity, bioaccumulation, and translocation of Cd-based quantum dots and Cd salt in white mustard

In this study, a model crop plant white mustard (Sinapis alba L.) was treated with an aqueous dispersion of silica-coated CdTe quantum dots (CdTe/SiO₂ QDs) in a 72-h short-term toxicity test. The toxicity was established via measurements of (i) the root length and (ii) the chlorophyll fluorescence. These results were compared to two other sources of cadmium, free Cd ions (CdCl₂) and prime un-shell nanoparticles CdTe QDs. Tested compounds were applied in concentrations representing 20 and 200 μM Cd. The uptake and translocation of Cd were investigated using inductively coupled plasma optical emission spectrometry (ICP-OES) and the spatial Cd distribution was investigated in detail applying laser induced breakdown spectroscopy (LIBS). The LIBS maps with a lateral resolution of 100 μm were constructed for the whole plants, and maps with a lateral resolution of 25 μm (micro-LIBS arrangement) were used to analyse only the most interesting parts of plants with Cd presence (e.g. root tips or a part crossing the root into the above-ground part). Our results show that the bioaccumulation patterns and spatial distribution of Cd in CdTe/SiO₂ QDs-treated plants differ from the plants of positive control and CdTe QDs. Fluorescence microscopy photographs revealed that CdTe/SiO₂ became adsorbed onto the plant surface in comparison to CdTe QDs. Further, a physico-chemical characterization of QDs before and after the test exposure showed only minor changes in the nanoparticle diameters and no tendencies of QDs for agglomeration or aggregation during the exposure.

Response of rhizospheric and endophytic bacterial communities of white mustard (Sinapis alba) to bioaugmentation of soil with the Pseudomonas sp. H15 strain

A factor that may significantly increase the efficacy of phytoextraction is soil bioaugmentation with specific bacteria, which can alter the composition of rhizospheric and endophytic bacterial communities. The aim of this study was to compare the effect of soil treatment with living (bioaugmentation) and dead (control) cells of the plant growth-promoting metal-resistant endophytic strain Pseudomonas sp. H15 on the bacterial community composition in the rhizo- and endo-sphere of white mustard during enhanced phytoextraction. The bacterial communities in the rhizosphere were dominated (51.7-68.2%) by Proteobacteria, regardless of the soil treatment or sampling point. A temporary increase in the number of sequences belonging to Gammaproteobacteria (up to 37.3%) was only observed 24 h after the soil treatment with living Pseudomonas sp. H15 cells, whereas for the remaining samples, the relative abundance of this class did not exceed 7.1%. The relative abundance of Proteobacteria in the endosphere of the roots, stems, and leaves of white mustard was higher in the control than in bioaugmented plants. The most pronounced dominance of the Gammaproteobacteria sequences was observed in the stems and leaves of the control plants at the first sampling point, which strongly indicates the ability of the plants to rapidly uptake DNA from soil and translocate it to the aboveground parts of the plants. Additionally, the bioaugmentation of the soil caused a diverse shift in the bacterial communities in the rhizo- and endo-sphere of white mustard compared to control. The most distinct differences, which were dependent on the treatment, were observed in the endosphere of plants at the beginning of the experiment and decreased over time. These results indicate that the rhizo- and endo-biome of white mustard reacts to soil bioaugmentation and may influence the efficiency of bacterial-assisted phytoextraction.

Glutamine as an Ammonia Donor in Catabolism of the Glucosinolate, Sinalbin, in Biosynthesis of 4-Hydroxybenzylamine

Amines synthesized by plants may be considered a dietary source of bioactive compounds, which are of interest due to possible health promoting effects. Developing Sinapis alba sprouts are known to produce 4-hydroxybenzylamine, but the reaction mechanism has not yet been established. We propose here a suggested metabolic pathway for the formation of 4-hydroxybenzylamine in S. alba plants. The catabolic sequence starts with a reaction between l-glutamine (Gln) as ammonia donor and 4-hydroxybenzyl carbocation, the enzymatic catalyzed hydrolysis product from sinalbin (4-hydroxybenzylglucosinolate). The suggested reactions are compared with alternative plant metabolic reactions used in the biosynthesis of biogenic amines.

Hydrocarbon Removal by Two Differently Developed Microbial Inoculants and Comparing Their Actions with Biostimulation Treatment

Bioremediation of soils polluted with petroleum compounds is a widely accepted environmental technology. We compared the effects of biostimulation and bioaugmentation of soil historically contaminated with aliphatic and polycyclic aromatic hydrocarbons. The studied bioaugmentation treatments comprised of the introduction of differently developed microbial inoculants, namely: an isolated hydrocarbon-degrading community C1 (undefined-consisting of randomly chosen degraders) and a mixed culture C2 (consisting of seven strains with well-characterized enhanced hydrocarbon-degrading capabilities). Sixty days of remedial treatments resulted in a substantial decrease in total aliphatic hydrocarbon content; however, the action of both inoculants gave a significantly better effect than nutrient amendments (a 69.7% decrease for C1 and 86.8% for C2 vs. 34.9% for biostimulation). The bioaugmentation resulted also in PAH removal, and, again, C2 degraded contaminants more efficiently than C1 (reductions of 85.2% and 64.5%, respectively), while biostimulation itself gave no significant results. Various bioassays applying different organisms (the bacterium Vibrio fischeri, the plants Sorghum saccharatum, Lepidium sativum, and Sinapis alba, and the ostracod Heterocypris incongruens) and Ames test were used to assess, respectively, potential toxicity and mutagenicity risk after bioremediation. Each treatment improved soil quality, however only bioaugmentation with the C2 treatment decreased both toxicity and mutagenicity most efficiently. Illumina high-throughput sequencing revealed the lack of (C1) or limited (C2) ability of the introduced degraders to sustain competition from indigenous microbiota after a 60-day bioremediation process. Thus, bioaugmentation with the bacterial mixed culture C2, made up of identified, hydrocarbon-degrading strains, is clearly a better option for bioremediation purposes when compared to other treatments.

Biodegradation Potential and Ecotoxicity Assessment in Soil Extracts Amended with Phenoxy Acid Herbicide (2,4-D) and a Structurally-Similar Plant Secondary Metabolite (Ferulic Acid)

Phenoxy acid 2,4-D (2,4-dichlorophenoxy acid) is one of the most commonly-used herbicide in agriculture. Biodegradation of 2,4-D can be stimulated by structurally-related plant secondary metabolites such as ferulic acid (FA). The aim of this study is to: (1) assess the potential of indigenous soil bacteria to degrade 2,4-D in the presence of FA by PCR analysis of functional tfdA genes, (2) to determine the influence of 2,4-D and FA on samples ecotoxicity using Phytotoxkit^® and Microtox^® biotests. The detection of tfdA genes varied depending on the enrichment of samples with FA. FA suppressed detection of the tfdA genes, 100 µM 2,4-D induced higher detection of studied amplicons, while 500 µM 2,4-D delayed their detection. The ecotoxicity response was specific and differed between plants (PE% Lepidium sativum >  Sinapis alba >  Sorghum saccharatum) and bacteria (PE% up to 99% for Vibrio fischeri). Our findings confirm that 2,4-D and FA had a toxic influence on the used organisms.

Gene expression, DNA damage and other stress markers in Sinapis alba L. exposed to heavy metals with special reference to sewage sludge application on contaminated sites

Bioindicators are promising tools used to detect the long-term effects of selected biosolids on plants development and should be implemented before large-scale supplementation of sewage sludge into the soil. The presented study shows the impact of sewage sludge application on metal-sensitive toxicity biological parameters (biomarkers) in Sinapis alba including: germination, root length, the activity of guaiacol peroxidase, the chlorophyll content, the level of DNA damage and the expression level of Ribulose-1,5-bisphosphate carboxylase/oxygenase (rbcL) and metallothionein (mt). We evaluated data from selected biomarkers in order to broaden our understanding of plants defense mechanisms against heavy metal contamination and the application of sewage sludge into soils. Overall, in contaminated soil after supplementation with both municipal sewage sludges, an increase in toxicity was noticed in DNA damage, mt and rbcl expression and total chlorophyll content. The supplementation of both soils with municipal sewage sludge caused a two-time induction in the mt expression. Moreover, clean soil supplemented with sewage sludge caused an increase in DNA damage shown as the tail moment from approximately 12 μm on control to 40 μm after supplementation. Even if those biosolids increased the initial germination, roots length, and biomass in comparison to the unamended soil, the toxicity was evidenced with other stress markers. Results showed, that in order to accurately assess the influence of sewage sludge application on plants the use of several specific biomarkers is required for safe land restoration. The conducted study also confirmed, both under biochemical and genotoxic tests, that iron enrichment for biosolids or contaminated soil can significantly reduce the bioavailability and toxicity of other metals.

Effect of white mustard cover crop residue, soil chemical fumigation and Trichoderma spp. root treatment on black-foot disease control in grapevine

BACKGROUND

Black-foot disease is one of the main soilborne fungal diseases affecting grapevine production worldwide. Two field experiments were established to evaluate the effect of white mustard cover crop residue amendment and chemical fumigation with propamocarb + fosetyl-Al combined with Trichoderma spp. root treatment on the viability of black-foot inoculum in soil and fungal infection in grafted plants and grapevine seedlings used as bait plants.

RESULTS

A total of 876 black-foot pathogen isolates were collected from grafted plants and grapevine seedlings used as bait plants in both fields. White mustard biofumigation reduced inoculum of Dactylonectria torresensis and the incidence and severity of black-foot of grapevine, but no added benefit was obtained when biofumigation was used with Trichoderma spp. root treatments. The effect of white mustard residues and chemical fumigation on populations of D. torresensis propagules in soil was inconsistent, possibly because of varying pretreatment inoculum levels.

CONCLUSION

Biofumigation with white mustard plants has potential for improving control of black-foot disease in grapevines. This control strategy can reduce soil inoculum levels and protect young plants from infection, providing grape growers and nursery propagators with more tools for developing integrated and sustainable control systems. © 2018 Society of Chemical Industry.

Study of the uptake and bioaccumulation of palladium nanoparticles by Sinapis alba using single particle ICP-MS

In recent years, increased palladium content has been found in the environment, due to its wide use in various fields, especially as catalytic converters. Palladium can be emitted as a range of soluble and insoluble compounds and in the form of palladium nanoparticles (PdNPs). The level of toxicity is equally dependent on concentration and form of palladium and hence, it is important to determine not only the total content of this element, but also its forms of occurrence. This study for the first time investigates the uptake degree and distribution of PdNPs by model plant Sinapis alba, in comparison with a platinum salt (Pd(NO₃)₂). An enzymatic digestion method which allows the extraction of PdNPs from the different plant tissues without altering their properties was applied. After extraction, samples were analysed by single particle inductively coupled plasma mass spectrometry (SP-ICP-MS) to provide information about the presences of palladium in nanoparticulated or dissolved form, the nanoparticle size and the nanoparticle number concentration. Significant amounts of PdNPs were found even in aboveground organs, but no significant changes in plant morphology were observed. Size distributions of PdNPs found in all tissues presented lower diameters than size distribution of the PdNPs stock suspension, suggesting that bigger nanoparticles are not taken up by the plant. The average size found is in good agreement between the different organs. Moreover, dissolved palladium was found in all samples, with the biggest contribution, in relative terms, observed in leaves followed by stems and roots.

Comprehensive analysis of fly ash induced changes in physiological/growth parameters, DNA damage and oxidative stress over the life cycle of Brassica juncea and Brassica alba

Fly ash (FA) being a heterogeneous mixture of heavy metal affects plant system in various ways. Previous studies have shown bioaccumulation of toxic metals in the plants and disturbance in cellular activities. Here, we have studied the impacts of FA treatment through the life cycle of economically important, annual crop plant mustard (Brassica juncea and Brassica alba). Result revealed that FA did not alter germination rate and photosynthetic pigment levels. Tolerance index of B. juncea was higher compared to B. alba. Seed setting was significantly affected by FA in B. alba. Significant increase in DNA damage was observed in both B. alba and B. juncea. Proline accumulation was significantly higher in B. alba. In B. juncea catalase activity and reduced glutathione content declined in initial days which were restored at the end of experimental period. Significant decrease in non-enzymatic antioxidants was noted in B. alba. Higher accumulation of Pb and As was noted in shoot of B. juncea and in B. alba Cu, Pb, Cr and As accumulated in shoots. As observed from these results, both plants could translocate certain toxic heavy metals from roots to the shoot which affected the physiological and biochemical balance and induced genotoxic response.

Oviposition Preference for Young Plants by the Large Cabbage Butterfly (Pieris brassicae ) Does not Strongly Correlate with Caterpillar Performance

The effects of temporal variation in the quality of short-lived annual plants on oviposition preference and larval performance of insect herbivores has thus far received little attention. This study examines the effects of plant age on female oviposition preference and offspring performance in the large cabbage white butterfly Pieris brassicae. Adult female butterflies lay variable clusters of eggs on the underside of short-lived annual species in the family Brassicaceae, including the short-lived annuals Brassica nigra and Sinapis arvensis, which are important food plants for P. brassicae in The Netherlands. Here, we compared oviposition preference and larval performance of P. brassicae on three age classes (young, mature, and pre-senescing) of B. nigra and S. arvensis plants. Oviposition preference of P. brassicae declined with plant age in both plant species. Whereas larvae performed similarly on all three age classes in B. nigra, preference and performance were weakly correlated in S. arvensis. Analysis of primary (sugars and amino acids) and secondary (glucosinolates) chemistry in the plant shoots revealed that differences in their quality and quantity were more pronounced with respect to tissue type (leaves vs. flowers) than among different developmental stages of both plant species. Butterflies of P. brassicae may prefer younger and smaller plants for oviposition anticipating that future plant growth and size is optimally synchronized with the final larval instar, which contributes >80% of larval growth before pupation.

Overlapping toxic effect of long term thallium exposure on white mustard (Sinapis alba L.) photosynthetic activity

BACKGROUND

Heavy metal exposure affect plant productivity by interfering, directly and indirectly, with photosynthetic reactions. The toxic effect of heavy metals on photosynthetic reactions has been reported in wide-ranging studies, however there is paucity of data in the literature concerning thallium (Tl) toxicity. Thallium is ubiquitous natural trace element and is considered the most toxic of heavy metals; however, some plant species, such as white mustard (Sinapis alba L.) are able to accumulate thallium at very high concentrations. In this study we identified the main sites of the photosynthetic process inhibited either directly or indirectly by thallium, and elucidated possible detoxification mechanisms in S. alba.

RESULTS

We studied the toxicity of thallium in white mustard (S. alba) growing plants and demonstrated that tolerance of plants to thallium (the root test) decreased with the increasing Tl(I) ions concentration in culture media. The root growth of plants exposed to Tl at 100 μg L(-1) for 4 weeks was similar to that in control plants, while in plants grown with Tl at 1,000 μg L(-1) root growth was strongly inhibited. In leaves, toxic effect became gradually visible in response to increasing concentration of Tl (100 - 1,000 μg L(-1)) with discoloration spreading around main vascular bundles of the leaf blade; whereas leaf margins remained green. Subsequent structural analyses using chlorophyll fluorescence, microscopy, and pigment and protein analysis have revealed different effects of varying Tl concentrations on leaf tissue. At lower concentration partial rearrangement of the photosynthetic complexes was observed without significant changes in the chloroplast structure and the pigment and protein levels. At higher concentrations, the decrease of PSI and PSII quantum yields and massive oxidation of pigments was observed in discolored leaf areas, which contained high amount of Tl. Substantial decline of the photosystem core proteins and disorder of the photosynthetic complexes were responsible for disappearance of the chloroplast grana.

CONCLUSIONS

Based on the presented results we postulate two phases of thallium toxicity on photosynthesis: the non-destructive phase at early stages of toxicant accumulation and the destructive phase that is restricted to the discolored leaf areas containing high toxicant content. There was no distinct border between the two phases of thallium toxicity in leaves and the degree of toxicity was proportional to the migration rate of the toxicant outside the vascular bundles. The three-fold (nearly linear) increase of Tl(I) concentration was observed in damaged tissue and the damage appears to be associated with the presence of the oxidized form of thallium - Tl(III).

Dissipation kinetics of alpha-cypermethrin and lambda-cyhalothrin residues in aboveground part of white mustard (Sinapis alba L.)

Dissipation of simultaneously applied insecticides alpha-cypermethrin and lambda-cyhalothrin was studied in a minor crop, aboveground part of white mustard (Sinapis alba L.). A validated gas chromatographic method (GC-ECD/NPD) was used to determine insecticide residues. Analytical performances were very satisfactory, with expanded uncertainties not higher than 14% (coverage factor k = 2, confidence level 95%). Dissipation of alpha-cypermethrin and lambda-cyhalothrin in white mustard followed first-order kinetics (R(2) between 0.953 and 0.995), with half-lives of 3.1-4.6 and 2.9-3.7 days respectively. Based on the results of this two-year study and the relevant residue regulation, alpha-cypermethrin and lambda-cyhalothrin treatments can be considered safe for crop protection, feeding animals and the environment.

Phytoremediation of lead-contaminated soil by Sinapis arvensis and Rapistrum rugosum

Nowadays, public concern relating to ecological deleterious effects of heavy metals is on the rise. To evaluate the potential of Rapistrum rugosum and Sinapis arvensis in lead- contaminate phytoremediate, a pot culture experiment was conducted. The pots were filled by soil treated with different rates of leadoxide (PbO) including 0 (control), 100, 200, 300, 400, and 500 mg Pb per 1 kg soil. Germinated seeds were sown. Surprisingly, with increasing concentration of Pb, dry weight of R. rugosum and S. arvensis did not decrease significantly. In both of species, the concentration of Pb was higher in roots than shoots. In general, S.arvensis was absorbed more Pb compared to R. rugosum. The results revealed high potential of R. rugosum and S. arvensis in withdrawing Pb from contaminated soil. For both species, a positive linear relation was observed between Pb concentration in soil and roots. However, linear relationship was not observed between Pb concentration in the soil and shoots. Although both species test had low ability in translocation Pb from roots to shoots but they showed high ability in uptake soil Pb by roots. Apparently, these plants are proper species for using in phytoremediation technology.

Metabolic Characteristics in Meal of Black Rapeseed and Yellow-Seeded Progeny of Brassica napus-Sinapis alba Hybrids

Breeding of yellow-seeded rapeseed (Brassica napus) is preferred over black-seeded rapeseed for the desirable properties of the former. This study evaluated the metabolites and nutritive values of black-seeded rapeseed meal and yellow-seeded meal from the progeny of a B. napus–Sinapis alba hybrid. Yellow-seed meal presented higher protein (35.46% vs. 30.29%), higher sucrose (7.85% vs. 7.29%), less dietary fiber (26.19% vs. 34.63%) and crude fiber (4.56% vs. 8.86%), and less glucosinolates (22.18 vs. 28.19 μmol/g) than black-seeded one. Amounts of ash (3.65% vs. 4.55%), phytic acid (4.98% vs. 5.60%), and total polyphenols (2.67% vs. 2.82%) were decreased slightly in yellow-seeded meal compared with black-seeded meal. Yellow-seeded meal contained more essential amino acids than black-seeded meal. Levels of the mineral elements Fe, Mn, and Zn in yellow-seeded meal were higher than black-seeded meal. By contrast, levels of P, Ca, and Mg were lower in yellow-seeded meal. Moreover, yellow-seeded meal showed lower flavonol (kaempferol, quercetin, isorhamnetin, and their derivatives) content than black-seeded meal. Comparison of metabolites between yellow and black rapeseed confirmed the improved nutritional value of meal from yellow-seeded B. napus, and this would be helpful to the breeding and improvement of rapeseed for animal feeding.

Potential for phytoextraction of copper by Sinapis alba and Festuca rubra cv. Merlin grown hydroponically and in vineyard soils

The extensive use of copper-bearing fungicides in vineyards is responsible for the accumulation of copper (Cu) in soils. Grass species able to accumulate Cu could be cultivated in the vineyard inter-rows for copper phytoextraction. In this study, the capacity of Festuca rubra cv Merlin and Sinapis alba to tolerate and accumulate copper (Cu) was first investigated in a hydroponic system without the interference of soil chemical-physical properties. After the amendment of Cu (5 or 10 mg Cu l-(1)) to nutrient solution, shoot Cu concentration in F. rubra increased up to 108.63 mg Cu kg(-1) DW, more than three times higher than in S. alba (31.56 mg Cu kg(-1) DW). The relationship between Cu concentration in plants and external Cu was dose-dependent and species specific. Results obtained from the hydroponic experiment were confirmed by growing plants in pots containing soil collected from six Italian vineyards. The content of soil organic matter was crucial to enhance Cu tolerance and accumulation in the shoot tissues of both plant species. Although S. alba produced more biomass than F. rubra in most soils, F. rubra accumulated significantly more Cu (up to threefold to fourfold) in the shoots. Given these results, we recommended that F. rubra cv Merlin could be cultivated in the vineyard rows to reduce excess Cu in vineyard soils.

Construction of a genetic linkage map and QTL analysis of erucic acid content and glucosinolate components in yellow mustard (Sinapis alba L.)

BACKGROUND

Yellow mustard (Sinapis alba L.) is an important condiment crop for the spice trade in the world. It has lagged behind oilseed Brassica species in molecular marker development and application. Intron length polymorphism (ILP) markers are highly polymorphic, co-dominant and cost-effective. The cross-species applicability of ILP markers from Brassica species and Arabidopsis makes them possible to be used for genetic linkage mapping and further QTL analysis of agronomic traits in yellow mustard.

RESULTS

A total of 250 ILP and 14 SSR markers were mapped on 12 linkage groups and designated as Sal01-12 in yellow mustard. The constructed map covered a total genetic length of 890.4 cM with an average marker interval of 3.3 cM. The QTL for erucic content co-localized with the fatty acid elongase 1 (FAE1) gene on Sal03. The self-(in)compatibility gene was assigned to Sal08. The 4-hydroxybenzyl, 3-indolylmethyl and 4-hydroxy-3-indolylmethyl glucosinolate contents were each controlled by one major QTL, all of which were located on Sal02. Two QTLs, accounting for the respective 20.4% and 19.2% of the total variation of 2-hydroxy-3-butenyl glucosinolate content, were identified and mapped to Sal02 and Sal11. Comparative synteny analysis revealed that yellow mustard was phylogenetically related to Arabidopsis thaliana and had undergone extensive chromosomal rearrangements during speciation.

CONCLUSION

The linkage map based on ILP and SSR markers was constructed and used for QTL analysis of seed quality traits in yellow mustard. The markers tightly linked with the genes for different glucosinolate components will be used for marker-assisted selection and map-based cloning. The ILP markers and linkage map provide useful molecular tools for yellow mustard breeding.

Salicylic acid-mediated establishment of the compatibility between Alternaria brassicicola and Brassica juncea is mitigated by abscisic acid in Sinapis alba

This work addresses the changes in the phytohormonal signature in the recognition of the necrotrophic fungal pathogen Alternaria brassicicola by susceptible Brassica juncea and resistant Sinapis alba. Although B. juncea, S. alba and Arabidopsis all belong to the same family, Brassicaceae, the phytohormonal response of susceptible B. juncea towards this pathogen is unique because the latter two species express non-host resistance. The differential expression of the PR1 gene and the increased level of salicylic acid (SA) indicated that an SA-mediated biotrophic mode of defence response was triggered in B. juncea upon challenge with the pathogen. Compared to B. juncea, resistant S. alba initiated enhanced abscisic acid (ABA) and jasmonic acid (JA) responses following challenge with this pathogen, as revealed by monitoring the expression of ABA-related genes along with the concentration of ABA and JA. Furthermore, these results were verified by the exogenous application of ABA on B. juncea leaves prior to challenge with A. brassicicola, which resulted in a delayed disease progression, followed by the inhibition of the pathogen-mediated increase in SA response and enhanced JA levels. Therefore, it seems that A. brassicicola is steering the defence response towards a biotrophic mode by mounting an SA response in susceptible B. juncea, whereas the enhanced ABA response of S. alba not only counteracts the SA response but also restores the necrotrophic mode of resistance by enhancing JA biosynthesis.

The effect of soil bioaugmentation with strains of Pseudomonas on Cd, Zn and Cu uptake by Sinapis alba L

The aim of this study was to assess the ability of selected metal resistant strains of the Pseudomonas genus to increase Zn, Cd and Cu uptake by the metalophyte Sinapis alba L. under laboratory conditions. Moreover, the mechanisms of the plant growth promotion in the tested strains and their impact on the shoots and roots of white mustard biomass were examined. Soil inoculation with the tested strains resulted in higher concentrations of Zn, Cd and Cu in the shoots and roots of the plants in comparison with those grown in non-inoculated soil. The highest phytoextraction enhancement was caused by Pseudomonas fluorescens MH15 which increased Zn, Cd and Cu accumulation in shoot tissue by 60%, 96% and 31%, respectively, in comparison with control plants. Moreover, all the tested strains also exhibited a significant increase of Cd translocation from roots to shoots of the white mustard. Three Pseudomonas putida (MH3, MH6, MH7) and two P. fluorescens biotype G and C (MH9 and MH15, respectively) strains had the ability to produce siderophore, 1-amino-cyclopropane-1-carboxylic acid deaminase, indole 3-acetic acid as well as hydrocyanic acid. Additionally, P. putida strains were also capable of solubilizing inorganic phosphate. The ability of the tested strains to increase the metal uptake in white mustard and their plant growth-promoting properties make them good candidates for supporting heavy metal phytoextraction as well as for plant growth promoting.

Phase-dependent phytoavailability of thallium--a synthetic soil experiment

The study deals with the environmental stability of Tl-modified phases (ferrihydrite, goethite, birnessite, calcite and illite) and phytoavailability of Tl in synthetically prepared soils used in a model vegetation experiment. The data presented here clearly demonstrate a strong relationship between the mineralogical position of Tl in the model soil and its uptake by the plant (Sinapis alba L.). The maximum rate of Tl uptake was observed for plants grown on soil containing Tl-modified illite. In contrast, soil enriched in Ksat-birnessite had the lowest potential for Tl release and phytoaccumulation. Root-induced dissolution of synthetic calcite and ferrihydrite in the rhizosphere followed by Tl mobilization was detected. Highly crystalline goethite was more stable in the rhizosphere, compared to ferrihydrite, leading to reduced biological uptake of Tl. Based on the results obtained, the mineralogical aspect must be taken into account prior to general environmental recommendations in areas affected by Tl.

Plants as models for chromium and nickel risk assessment

The adverse effects of Cr(III), Cr(VI), and Ni(II) expressed as root and shoot growth inhibition, metal accumulation and translocation throughout plants, and genotoxicity study were examined. To examine phytoxicity and metal accumulation, Vicia sativa, Raphanus sativus, Zea mays and Sinapis alba plants were used. Except for S. alba root growth inhibition, Ni had the strongest inhibitory effect on root and shoot growth. The inhibitory rank order based on IC₅₀ values was Ni(II) > Cr(VI) > Cr(III). Z. mays was the least sensitive to all metals. While the accumulation of Cr was higher in the roots than the upper plant parts, Ni transport to shoots was at least two times higher than that of Cr. The highest accumulation of Cr was found in Z. mays and that of Ni in V. sativa and Z. mays roots. For all plants, the translocation factor was higher for Cr(VI) than for Cr(III). The translocation factor for Ni was several times higher than those of Cr. For mutagenicity assay, root tips of V. sativa, R. sativus and Z. mays were used. All metals exerted a significant increase of chromosomal aberrations and the rank order of aberrations was: Cr(VI) > Ni(II) > Cr(III). Genotoxic effects of metals were also determined by analysis of micronuclei frequency in the pollen tetrads of Tradescantia plants. None of metals significantly stimulated micronuclei frequency and the genotoxic effect decreased in the following order: Cr(VI) ≥ Ni(II) > Cr(III).

Development of near-isogenic lines and identification of markers linked to auxinic herbicide resistance in wild mustard (Sinapis arvensis L.)

BACKGROUND

Auxinic herbicides are widely used for selective control of many broadleaf weeds, e.g. wild mustard. An auxinic-herbicide-resistant wild mustard biotype may offer an excellent model system to elucidate the mechanism of action of these herbicides. Classical genetic analyses demonstrate that the wild mustard auxinic herbicide resistance is determined by a single dominant gene. Availability of near-isogenic lines (NILs) of wild mustard with auxinic herbicide resistance (R) and herbicide susceptibility (S) will help to study the fitness penalty as well as the precise characterization of this gene.

RESULTS

Eight generations of backcrosses were performed, and homozygous auxinic-herbicide-resistant and auxinic-herbicide-susceptible NILs were identified from BC(8) F(3) families. S plants produced significantly more biomass and seed compared with R plants, suggesting that wild mustard auxinic herbicide resistance may result in fitness reduction. It was also found that the serrated margin of the first true leaf was closely linked to auxinic herbicide resistance. Using the introgressed progeny, molecular markers linked to auxinic herbicide resistance were identified, and a genetic map was constructed.

CONCLUSION

The fitness penalty associated with the auxinic herbicide resistance gene may explain the relatively slow occurrence and spread of auxinic-herbicide-resistant weeds. The detection of the closely linked markers should hasten the identification and characterization of this gene.

Effect of illite and birnessite on thallium retention and bioavailability in contaminated soils

The influence of illite and birnessite (δ-MnO(2)) amendments on the retention and bioavailability of Tl in contaminated soils was investigated. The efficiency of both phases was evaluated using Tl uptake by white mustard (Sinapis alba L.), sequential extraction and sorption experiments. The obtained data demonstrate that the application of birnessite can effectively transform Tl from the labile (easily mobilizable) fraction to its reducible form, thus lowering Tl bioavailability in soil and subsequent accumulation by plants. The Mn oxide added to the soils reduced substantially Tl uptake; Tl levels in the plants decreased by up to 50%, compared to the non-amended soil. The effect of illite on the immobilization and uptake of Tl was less pronounced, and in the carbonate-rich Leptosol has not been proved at all, suggesting the importance of bulk soil mineralogy and nature of the soil sorption complex on the behavior of this amendment. Therefore, the general applicability of illite for Tl stabilization in soils seems to be limited and strongly dependent on soil composition. In contrast, the use of birnessite like soil additive might be an efficient and environment-friendly solution for soil systems contaminated with Tl.

Inorganic materials as ameliorants for soil remediation of metal toxicity to wild mustard (Sinapis arvensis L.)

The ameliorating effects of different inorganic materials were investigated on a soil originating from a zinc smelter dumping site contaminated by toxic metals. Wild mustard (Sinapis arvensis L.) was used as a test plant. The soil was amended with different doses of mining sludge, Perferric Red Latosol (LVj), steel shots, cyclonic ash, silifertil, and superphosphate. The most effective amendments improved plant growth with 45% and reduced metal uptake by over 70% in comparison to untreated soil. Reductions in availability as estimated by BaCl2-extractable metals reached up to 90% for Zn and 65% for Cd as compared to unamended soil. These reductions were associated with lower shoot and root metal contents. Shoot Zn content was reduced from 1,369 microg g(-1) in plants grown on untreated soil to 377 microg g(-1) when grown on cyclonic ash amended soil while Cd decreased from 267 to 44 microg g(-1) in steel shots amended soil. Superphosphate addition had no ameliorating effect. On the contrary, it increased BaCl2-extractable amounts of Zn. Considering all parameters we determined, steel shots, cyclonic ash and silifertil are the most promising for remediating metal contaminated soil in the tropics. Further studies evaluating impacts, cost-effectiveness and durability of effects will be conducted.

Environmental toxicity testing of contaminated soil based on microcalorimetry

Contaminated site assessment and monitoring requires efficient risk-management tools including innovative environmental toxicity tests. The first application of microcalorimetry for toxicity testing draw the attention to a possible new tool to increase sensitivity, to eliminate matrix effect and to study effect-mechanism. A Thermal Activity Monitor (TAM) microcalorimeter was used for measuring the heat production of various test organisms when getting in contact with sterile toxic soils. Well known bacterial (Azomonas agilis), animal (Folsomia candida) and plant test organisms (Sinapis alba) were tested for heat production. The heat response of selected testorganisms was measured in case of metal (Cu and Zn) and organic pollutant (Diesel oil, DBNPA and PCP) contaminated soils. In addition to the quantitative determination of the heat production, the mechanism of the toxic effect can be characterized from the shape of the power-time curve (slope of the curve, height and time of the maximum). In certain concentration ranges the higher the pollutant concentration of the soil the lower the maximum of the time-heat curve. At low pollutant concentrations an increased heat production was measured in case of A. agile and 20 and 200 mg Zn kg(-1) soil. The microcalorimetric testing was more sensitive in all cases than the traditional test methods. Our results showed that the microcalorimetric test method offers a new and sensitive option in environmental toxicology, both for research and routine testing.

Gene activation cascade triggered by a single photoperiodic cycle inducing flowering in Sinapis alba

Molecular genetic analyses in Arabidopsis disclosed a genetic pathway whereby flowering is induced by the photoperiod. This cascade is examined here within the time course of floral transition in the long-day (LD) plant Sinapis alba induced by a single photoperiodic cycle. In addition to previously available sequences, the cloning of CONSTANS (SaCO) and FLOWERING LOCUS T (SaFT) homologues allowed expression analyses to be performed to follow the flowering process step by step. A diurnal rhythm in SaCO expression in the leaves was observed and transcripts of SaFT were detected when light was given in phase with SaCO kinetics only. This occurred when day length was extended or when a short day was shifted towards a 'photophile phase'. The steady-state level of SaFT transcripts in the various physiological situations examined was found to correlate like a rheostat with floral induction strength. Kinetics of SaFT activation were also consistent with previous estimations of translocation of florigen out of leaves, which could actually occur after the inductive cycle. In response to one 22-h LD, initiation of floral meristems by the shoot apical meristem (SAM) started about 2 days after activation of SaFT and was marked by expression of APETALA1 (SaAP1). Meanwhile, LEAFY (SaLFY) was first up-regulated in leaf primordia and in the SAM. FRUITFULL (SaFUL) was later activated in the whole SAM but excluded from floral meristems. These patterns are integrated with previous observations concerning upregulation of SUPPRESSOR OF OVEREXPRESSION OF CO1 (SaSOC1) to provide a temporal and spatial map of floral transition in Sinapis.

Head-neck domain of Arabidopsis myosin XI, MYA2, fused with GFP produces F-actin patterns that coincide with fast organelle streaming in different plant cells

BACKGROUND

The cytoskeletal mechanisms that underlie organelle transport in plants are intimately linked to acto-myosin function. This function is mediated by the attachment of myosin heads to F-actin and the binding of cargo to the tails. Acto-myosin also powers vigorous cytoplasmic streaming in plant cells. Class XI myosins exhibit strikingly fast velocities and may have extraordinary roles in cellular motility. Studies of the structural basis of organelle transport have focused on the cargo-binding tails of myosin XI, revealing a close relationship with the transport of peroxisomes, mitochondria, and Golgi-vesicles. Links between myosin heads and F-actin-based motility have been less investigated. To address this function, we performed localization studies using the head-neck domain of AtMYA2, a myosin XI from Arabidopsis.

RESULTS

We expressed the GFP-fused head-neck domain of MYA2 in epidermal cells of various plant species and found that it associated with F-actin. By comparison to other markers such as fimbrin and talin, we revealed that the myosin-labeled F-actin was of a lower quality and absent from the fine microfilament arrays at the cell cortex. However, it colocalized with cytoplasmic (transvacuolar) F-actin in areas coinciding with the tracks of fast organelles. This observation correlates well with the proposed function of myosin XI in organelle trafficking. The fact that organelle streaming was reduced in cells expressing the GFP-MYA2-head6IQ indicated that the functionless motor protein inhibits endogenous myosins. Furthermore, co-expression of the GFP-MYA2-head6IQ with other F-actin markers disrupted its attachment to F-actin. In nuclei, the GFP-myosin associated with short bundles of F-actin.

CONCLUSION

The localization of the head of MYA2 in living plant cells, as investigated here for the first time, suggests a close linkage between this myosin XI and cytoplasmic microfilaments that support the rapid streaming of organelles such as peroxisomes. Potential roles of MYA2 may also exist in the cell nucleus. Whether the low quality of the F-actin-labeling by MYA2-head6IQ compared to other F-actin-binding proteins (ABPs) signifies a weak association of the myosin with actin filaments remains to be proven by other means than in vivo. Clues for the mode of contact between the myosin molecules and F-actin so far cannot be drawn from sequence-related data.

Transport of cadmium and assessment of phytotoxicity after electrokinetic remediation

The use of ethylene diamine tetraacetic acid (EDTA) on the electrokinetic removal of cadmium-contaminated soil was evaluated. A total of four different tests were conducted using EDTA as a washing solution as well as a purging solution at the electrode compartments. The efficiency of electrokinetic extraction was significantly influenced by the pH of the soil medium. The results show that EDTA was effective in desorbing cadmium at a high pH, with Cd-EDTA(-) anion complexes migrating toward the anode. At low pH values near the anode area, cadmium existed as Cd(2+), migrating toward the cathode. Such contradicting directions of cadmium have resulted in its detrimental removal from the soil cell. However, accumulation of cadmium near the cathode was observed at the end of the tests due to the dominating low pH in the soil cell. The phytotoxicity after the electrokinetic process was investigated using Sorghum saccharatum, Lepidium sativum and Sinapis alba plants. The germination index was a major endpoint estimated by measuring seed germination and shoot elongation. The results obtained show that the phytotoxicity was increased after electrokinetic extraction. Despite, the extensive cadmium removal from two-thirds of the cell, the low pH of the soil was the principal parameter exhibiting the phytotoxicity.

Molecular interaction between Methylobacterium extorquens and seedlings: growth promotion, methanol consumption, and localization of the methanol emission site

Four Methylobacterium extorquens strains were isolated from strawberry (Fragaria x ananassa cv. Elsanta) leaves, and one strain, called ME4, was tested for its ability to promote the growth of various plant seedlings. Seedling weight and shoot length of Nicotiana tabacum, Lycopersicon esculentum, Sinapis alba, and Fragaria vesca increased significantly in the presence of the pink-pigmented facultative methylotroph (PPFM), but the germination behaviour of seeds from six other plants was not affected. The cell-free supernatant of the bacterial culture stimulated germination, suggesting the production of a growth-promoting agent by the methylotroph. Methanol emitted from N. tabacum seedlings, as determined by proton-transfer-reaction mass spectrometry (PTR-MS), ranged from 0.4 to 0.7 ppbv (parts per billion by volume), while significantly lower levels (0.005 to 0.01 ppbv) of the volatile alcohol were measured when the seedlings were co-cultivated with M. extorquens ME4, demonstrating the consumption of the gaseous methanol by the bacteria. Additionally, by using cells of the methylotrophic yeast Pichia pastoris transformed with the pPICHS/GFP vector harbouring a methanol-sensitive promoter in combination with the green fluorescence protein (GFP) reporter gene, stomata were identified as the main source of the methanol emission on tobacco cotyledons. Methylobacterium extorquens strains can nourish themselves using the methanol released by the stomata and release an agent promoting the growth of the seedlings of some crop plants.

Cuticular uptake of xenobiotics into living plants. Part 2: influence of the xenobiotic dose on the uptake of bentazone, epoxiconazole and pyraclostrobin, applied in the presence of various surfactants, into Chenopodium album, Sinapis alba and Triticum aestivum leaves

This study has determined the uptake of three pesticides, applied as commercial or model formulations in the presence of a wide range of surfactants, into the leaves of three plant species (bentazone into Chenopodium album L. and Sinapis alba L., epoxiconazole and pyraclostrobin into Triticum aestivum L.). The results have confirmed previous findings that the initial dose (nmol mm(-2)) of xenobiotic applied to plant foliage is a strong, positive determinant of uptake. This held true for all the pesticide formulations studied, although surfactant concentration was found to have an effect. The lower surfactant concentrations studied showed an inferior relationship between the amount of xenobiotic applied and uptake. High molecular mass surfactants also produced much lower uptake than expected from the dose uptake equations in specific situations.

Ionic thiocyanate (SCN-) production from 4-hydroxybenzyl glucosinolate contained in Sinapis alba seed meal

Meal produced from Sinapis alba seed by crushing to remove oil contains a glucosinolate that when hydrolyzed produces phytotoxic allelochemicals; however, the responsible compounds and pathways for their production have not been elucidated. S. alba seed meal and partially purified extracts containing 4-hydroxybenzyl glucosinolate were included in experiments to identify and monitor enzymatically released products using GC-MS and HPLC-MS. The initial product, 4-hydroxybenzyl isothiocyanate, was unstable in aqueous media, showing a half-life of 321 min at pH 3.0, decreasing to 6 min at pH 6.5. More alkaline pH values decrease the stability of 4-hydroxybenzyl isothiocyanate by promoting the formation of a proposed quinone that hydrolyzes to SCN-. Measurement of SCN- showed stoichiometric release from S. alba meal at 48 h when buffered at pH values as low as 4.0, demonstrating that SCN- production in soil is not only probable but likely responsible for observed phytoxicity of the meal.

Immunocytochemistry of pectins in shoot apical meristems: consequences for intercellular adhesion

The nature of pectins (acidic, methyl-, or acetyl-esterified) in the shoot meristem of Sinapis alba was assessed by immunocytochemistry with the 2F4 monoclonal antibody in light and electron microscopy. This antibody is specific for "egg-boxes"--the polygalacturonic acid conformation induced by calcium as described in Liners et al. (Plant Physiol. 99: 1099-1104, 1992). Hardly any acidic pectin was detected in meristem walls; the pectins were largely methyl-esterified and esterified by acetyl groups and/or other esters. After in situ chemical or enzymatic de-esterification, labeling was distributed over the primary wall and the middle lamella of meristematic cells. Acidic pectin and Ca2+-cross-linked homogalacturonans were absent from the pit fields, where plasmodesmata traverse the middle lamella. The type and distribution of pectins are discussed in relation to cellular adhesion between active meristem cells.