Soil Pot Culture Research Articles

Phytotoxicity and genotoxicity study of reactive red 141 dye on mung bean (Vigna radiata (L.) Wilczek) seedlings.

Reactive Red (RR) 141 dye is widely used in various industrial applications, but its environmental impact remains a growing concern. In this study, the phytotoxic and genotoxic effects of RR 141 dye on mung bean seedlings (Vigna radiata (L.) Wilczek) were investigated, serving as a model for potential harm to plant systems. Short-term (14 days) and long-term (60 days) experiments in paddy soil pot culture exposed mung bean seedlings to RR 141 dye. The dye delayed germination and hindered growth, significantly reducing germination percentage and seedling vigor index (SVI) at concentrations of 50 and 100ml/L. In short-term exposure, plumule and radical lengths dose-dependently decreased, while long-term exposure affected plant length and grain weight, leaving pod-related parameters unaffected. To evaluate genotoxicity, high annealing temperature-random amplified polymorphic DNA (HAT-RAPD) analysis was employed with five RAPD primers having 58-75% GC content. It detected polymorphic band patterns, generating 116 bands (433 to 2857bp) in plant leaves exposed to the dye. Polymorphisms indicated the appearance/disappearance of DNA bands in both concentrations, with decreased genomic template stability (GTS) values suggesting DNA damage and mutation. These findings demonstrate that RR 141 dye has a significant impact on genomic template stability (GTS) and exhibits phytotoxic and genotoxic responses in mung bean seedlings. This research underscores the potential of RR 141 dye to act as a harmful agent within plant model systems, highlighting the need for further assessment of its environmental implications.

Cellular Cd2+ fluxes in roots confirm increased Cd availability to rice (Oryza sativa L.) induced by soil acidifications

Soil acidifications become one of the main causes restricting the sustainable development of agriculture and causing issues of agricultural product safety. In order to explore the effect of different acidification on soil cadmium (Cd) availability, soil pot culture and hydroponic (soil potting solution extraction) were applied, and non-invasive micro-test technique (NMT) was combined. Here three different soil acidification processes were simulated, including direct acidification by adding sulfuric acid (AP1), acid rain acidification (AP2) by adding artificial simulated acid rain and excessive fertilization acidification by adding (NH4)2SO4 (AP3). The results showed that for direct acidification (AP1), DTPA-Cd concentration in field soils in Liaoning (S1) and Zhejiang (S2) increased by 0.167 - 0.217 mg/kg and 0.181 - 0.346 mg/kg, respectively, compared with control group. When soil pH decreased by 0.45 units in S1, the Cd content of rice stems, leaves and roots increased by 0.48 to 6.04 mg/kg and 2.58 to 12.84 mg/kg, respectively, When the pH value of soil S1 and S2 decreased by 0.20 units, the average velocity of Cd2+ at 200 µm increased by 10.03 - 33.11 pmol/cm2/sec and 21.33 -52.86 pmol/cm2/sec, respectively, and followed the order of AP3 > AP2 > AP1. In summary, different acidification measures would improve the effectiveness of Cd, under the same pH reduction condition, fertilization acidification increased Cd availability most significantly.

Optimization of integrated phytoremediation system (IPS) for enhanced lead removal and restoration of soil microbial activities

Improving phytoremediation efficiency in lead (Pb) contaminated soil through either bacterial or fungal inoculants have extensively been studied with different successes and limitations. In this study, co-application of bacteria and fungi have been investigated for development of an integrated phytoremediation system (IPS) for efficient Pb removal and restoration of soil microbial and enzymatic activities in degraded soil. For this purpose, Pb tolerant bacterial and fungal strains were firstly analyzed for antifungal and antibacterial activities through disc diffusion method. Afterwards, the co-inoculation studies were performed to investigate the effects on phytoavailability and uptake of Pb by Pelargonium hortorum through soil incubation and pot culture experiments, respectively. Results indicated significant (p < 0.05) antibacterial activity of Mucor spp. against bacterial species (Klebsiella variicola and K. quasipneumoniae). The highest significant increase in extractable Pb fraction (5.0–folds) was observed when soil was co-inoculated with Aspergillus flavus + Microbacterium paraoxydans compared to the control soil (un-inoculated soil) at 2000 mg Pb kg−1 concentration. Similarly, uptake results also indicated significantly higher Pb uptake in plants inoculated with A. flavus + M. paraoxydans. Soil microbial results indicated significant decrease in microbial health indicators and enzymatic activities with increasing Pb concentration and exposure time, as compared to control soil. A relatively severe decline was observed in soil respiration and dehydrogenase (DEH) activities by 2.8– and 2.5–folds, respectively at 2000 mg Pb kg−1 of soil. The optimized IPS was effective for restoring enzymatic activities in Pb contaminated soil and could be applied for sustainable restoration of Pb contaminated soil.

Phytohormones-induced senescence efficiently promotes the transport of cadmium from roots into shoots of plants: A novel strategy for strengthening of phytoremediation

Due to the long growth period of plants, phytoremediation is time costly. Improving the accumulation of cadmium (Cd) in shoots of plants will promote the efficiency of phytoremediation. In this study, two senescence-relative phytohormones, abscisic acid (ABA) and salicylic acid (SA), were applied to strengthening phytoremediation of Cd by tall fescue (Festuca arundinacea S.). Under hydroponic culture, phytohormones treatment increased the Cd content of shoots 11.4-fold over the control, reaching 316.3 mg/kg (dry weight). Phytohormones-induced senescence contributes to the transport of heavy metals, and HMA3 was found to play a key role in this process. Additionally, this strategy could strengthen the accumulation of Cu and Zn in tall fescue shoots. Moreover, in soil pot culture, the strategy increased shoot Cd contents 2.56-fold over the control in tall fescue, and 2.55-fold over the control in Indian mustard (Brassica juncea L.), indicating its comprehensive adaptability and potential use in the field. In summary, senescence-induced heavy metal transport is developed as a novel strategy to strengthen phytoremediation. The strategy could be applied at the end of phytoremediation with an additional short duration (7 days) with comprehensive adaptability, and markedly strengthen the phytoremediation in the field.

Differential Response of Sugar Beet to Long-Term Mild to Severe Salinity in a Soil–Pot Culture

Attempts to cultivate sugar beet (Beta vulgaris spp. vulgaris) in the sub-tropical saline soils are ongoing because of its excellent tolerance to salinity. However, the intrinsic adaptive physiology has not been discovered yet in the sub-tropical climatic conditions. In this study, we investigated morpho-physiological attributes, biochemical responses, and yield of sugar beet under a gradient of salinity in the soil–pot culture system to evaluate its adaptive mechanisms. Results exhibited that low and high salinity displayed a differential impact on growth, photosynthesis, and yield. Low to moderate salt stress (75 and 100 mM NaCl) showed no inhibition on growth and photosynthetic attributes. Accordingly, low salinity displayed simulative effect on chlorophyll and antioxidant enzymes activity which contributed to maintaining a balanced H2O2 accumulation and lipid peroxidation. Furthermore, relative water and proline content showed no alteration in low salinity. These factors contributed to improving the yield (tuber weight). On the contrary, 250 mM salinity showed a mostly inhibitory role on growth, photosynthesis, and yield. Collectively, our findings provide insights into the mild–moderate salt adaptation strategy in the soil culture test attributed to increased water content, elevation of photosynthetic pigment, better photosynthesis, and better management of oxidative stress. Therefore, cultivation of sugar beet in moderately saline-affected soils will ensure efficient utilization of lands.

Effects of Some Chelators and Surfactants on Hyperaccumulator Sedum alfredii Hance Remediating Contaminated Soil

ABSTRACTThe effects of some chelators and surfactants on the hyperaccumulator Sedum alfredii Hance remediating co-contaminated soil contained 0.85 mgkg−1 Cd and 1.138 mg kg−1 PAHs (16 kinds of priority control polycyclic aromatic hydrocarbons by USEPA) were determined using soil pot culture experiment. Results showed that Cd capacity in shoot of S. alfredii was 16.88 µg pot−1 in treatment control 4 without additions. By contrast, Cd capacities in shoots were significantly increased by 37.6–270.9%, including CEDTA+SA, CEDTA+TW80, CSA+TW80+EDTA and CSA+TW80+CA as 216.6%, 42.4%, 84.0% and 65.4%, respectively. The degradation of PAHs in the rhizosphere of S. alfredii was significantly increased (p < .05) by 24.1%, 27.9%, 20.6%, 30.5% and 24.9% for the treatment of CEDTA+SA, CEDTA+TW80, CCA+SA, CSA+TW80+EDTA and CSA+TW80+CA, respectively. Thus, the treatment of CEDTA+SA, CEDTA+TW80, CSA+TW80+EDTA and CSA+TW80+CA could significantly improve the accumulation of Cd in S. alfredii and also significantly increased PAH degradation in its rhizosphere, which was of great practical significance for phytoremediation of Cd-PAHs co-contaminated soil.

Clean extracts from accumulator efficiently improved Solanum nigrum L. accumulating Cd and Pb in soil

Abstract To find more clean and efficient chelator promoted hyperaccumulation of heavy metal from contaminated soil is a challenge in phytoremediation. The aim of this experiment was to explore the roles of aqueous extracts from the roots, stems and leaves of three accumulators on Solanum nigrum L. accumulating Cd and Pb from soil in comparation with the chelator Ethylenediaminetetraacetic acid (EDTA). The results of soil pot culture experiment showed that Cd and Pb concentrations of S. nigrum shoot significantly increased by 62.1% and 39.8% when the stem extracts of Bidens tripartita L. (BTS) was spiked to soil, which were higher (p

Stem aqueous extracts of accumulator Bidens tripartita L. strongly promoted Solanum nigrum L. Cd hyperaccumulation from soil

The effects of aqueous extracts from bio-resources on Solanum nigrum L. Cd hyperaccumulation were determined with EDTA as control. Soil pot culture experiment and Leaching experiment were arranged and conducted. The results showed that stem extracts of Bidens tripartita L. (BT-S) significantly increased (by 61.0%) Cd shoot concentration in S. nigrum, which was higher compared (p < 0.05) to EDTA addition (32.4%), and the plants grew well. However, S. nigrum shoot biomass significantly decreased by 23.9% (p < 0.05) in the case of EDTA addition. The extraction rate of BT-S was 56.2% in the soil leaching experiment, and the extractable Cd concentration in soil in BT-S treatment was 69.7% higher compared to control. The concentrations of soluble polysaccharides, total organic acids and reducing sugars in the BT-S treatment were much higher than for other extracts, which may partly be the reason for it strong stimulation of S. nigrum Cd hyperaccumulation from the soil. The aqueous extracts of B. tripartita stems (BT-S) significantly increased (p < 0.05) S. nigrum hyperaccumulating Cd. This new chelator that can replace EDTA is of great significance for phytoremediation.

Strengthening role and the mechanism of optimum nitrogen addition in relation to Solanum nigrum L. Cd hyperaccumulation in soil

Solanum nigrum L. has a high potential for the remediation of Cd-contaminated soil, and nitrogen fertilizer supply is an effective method to further improve its phytoremediation potential. The soil pot culture experiment was used to explore 4 kinds of nitrogen fertilizers the best fertilizer addition concentrations and their strengthening mechanisms. The results showed that S. nigrum biomass increased with increasing N doses until 800 mg kg−1, where the biomass reached maximum and no longer improved (p < 0.05). However, Cd concentration accumulated by S. nigrum and the extractable Cd concentration in soil did not show a significant decrease (p < 0.05). In this experiment, when N fertilizer was added at 800 mg kg−1 (NH4HCO3, NH4Cl, (NH4)2SO4 and CH4N2O fertilizers), the biomass of the aboveground S. nigrum parts improved to the maximum under (NH4)2SO4 and CH4N2O treatments, i.e. 5.86 g pot−1 and 5.83 g pot−1, increased by 5.92- and 5.89-fold, respectively (p < 0.05), compared to the controls without N fertilizers addition. At the same time, Cd phytoaccumulation in plants was elevated to 128.40 μg pot−1 and 129.14 μg pot−1, increased by 6.20- and 6.24-fold, respectively (p < 0.05), compared to control with no fertilizer added. The results of this experiment demonstrated that Cd phytoextraction capacity (μg pot−1) was the strongest under (NH4)2SO4 and CH4N2O treatments at N content of 800 mg kg−1, when plant nutrient recovery reached the maximum, and these 2 types of nitrogen fertilizers could be utilized to remediate Cd-contaminated soil in field experiments or even in practice.

Selenium spiked in soil promoted zinc accumulation of Chinese cabbage and improved its antioxidant system and lipid peroxidation

Selenium (Se) and zinc (Zn) are necessary mineral nutrients for human body but millions of people have an inadequate intake of them, and eat food enriched with Se and Zn may minimize these problems. Chinese cabbage is an important food in people's daily life. The aim of this study was to evaluate the effects of single Se, Zn and their combination treatment in soil on their accumulation, antioxidant system and lipid peroxidation in roots and leaves of Chinese cabbage using soil pot culture experiment. When 0.5 mg kg−1 Se +30 mg kg−1 Zn and 1.0 mg kg−1 Se +30 mg kg−1 Zn were spiked in soils, Zn concentrations in roots and leaves of Chinese cabbage were significantly increased (p < 0.05) by 20.2%, 37.8% and 17.9%, 34.1% respectively compared to the treatment of 30 mg kg−1 Zn added, and the latter was significantly higher (p < 0.05) than that of former, indicating Se significantly promoted Zn accumulation. Almost all physiological indexes including POD, SOD, CAT, APX, GR, Chlorophyll a, Chlorophyll b, Carotenoids, MDA and Free proline in the treatments of Se or Zn spiked were significantly improved (p < 0.05) or basically unaffected compared to the control without Se or Zn added. The biomass change trends were similar with these indexes either. These results showed that the addition in soil of Se and Zn significantly increased their accumulation in Chinese cabbage without affected its formal growth. Particularly, the addition of Se promoted Zn accumulation. The conclusions were more important reference for the production practice of cash crop enriched of Se and Zn either.

Antioxidative enzymes activity and thiol metabolism in three leafy vegetables under Cd stress

The enrichment of Cadmium in vegetables is threatening human health. The study aimed to screen Cd low-enriched leafy vegetables and explore whether antioxidative enzymes and heavy metal chelators are synergistic defensive mechanisms. In this paper, the Cd accumulation and translocation of garland chrysanthemum (Chrysanthemum coronarium L.), spinach (Spinacia oleracea L.), and lettuce (Lactuca sativa L.) were examined by soil pot culture and hydroponic experiments. The responses of oxidative stress markers, antioxidative enzymes activity, and thiol pool (cysteine, γ-glutamylcysteine, glutathione, and phytochelatins) content to Cd stress were assayed. The results showed that Garland chrysanthemum was Cd low-uptake species. The soil Cd safety thresholds for spinach, lettuce, and garland chrysanthemum were 0.41, 0.49, and 9.10 mg kg–1, respectively. The order of root phytochelatins (PCs) concentration was consistent with that of plant tolerance index (TI): garland chrysanthemum > spinach > lettuce. While the order of the ratio of shoot Cd to root Cd (SR ratio) was exactly the opposite of that of TI. In lettuce root, activity of superoxide dismutase, peroxidase, and catalase decreased significantly under Cd stress. Nevertheless those parameters in the roots of spinach and lettuce maintained steady, or even enhanced. In conclusion, the Cd translocation and partition in plant, antioxidative defense, and PCs homeostasis played an important role in the Cd tolerance of vegetables.

Enhanced phytoremediation of cadmium and/or benzo(a)pyrene contaminated soil by hyperaccumlator Solanum nigrum L.

ABSTRACTThe role of same amendment on phytoremediating different level contaminated soils is seldom known. Soil pot culture experiment was used to compare the strengthening roles of cysteine (CY), EDTA, salicylic acid (Sa), and Tween 80 (TW) on hyperaccumulator Solanum nigrum L. phytoremediating higher level of single cadmium (Cd) or Benzo(a)pyrene (BAP) and their co-contaminated soils. Results showed that the Cd capacities (ug pot−1) in shoots of S. nigrum in the combined treatment T0.1EDTA+0.9CY were the highest for the 5 and 15 mg kg−1 Cd contaminated soils. When S. nigrum remediating co-contaminated soils with higher levels of Cd and BAP, that is, 5 mg kg−1 Cd + 1 mg kg−1 BAP and 15 mg kg−1 Cd + 2 mg kg−1 BAP, the treatment T0.9CY+0.9Sa+0.3TW showed the best enhancing remediation role. This results were different with co-contaminated soil with 0.771 mg kg−1 Cd + 0.024 mg kg−1 BAP. These results may tell us that the combine used of CY, SA, and TW were more useful for the contaminated soils with higher level of Cd and/or BAP. In the combined treatments of Sa+TW, CY was better than EDTA.

Characteristics and mechanisms of acrylate polymer damage to maize seedlings

Superabsorbent acrylate polymers (SAPs) have been widely used to maintain soil moisture in agricultural management, but they may cause damage to plants, and the mechanisms are not well understood. In this study, seed germination, soil pot culture, hydroponic experiments, and SAPs degradation were conducted to investigate damage characteristics and mechanisms associated with SAPs application. The Results showed that SAPs inhibited maize growth and altered root morphology (irregular and loose arrangement of cells and breakage of cortex parenchyma), and the inhibitory effects were enhanced at higher SAPs rates. After 1h SAP hydrogels treatment, root malondialdehyde (MDA) content was significantly increased, while superoxide dismutase (SOD) and catalase (CAT) content were significantly decreased. Hydroponics experiment indicated that root and shoot growth was inhibited at 2.5mgL−1 acrylic acid (AA), and the inhibition was enhanced with increasing AA rates. This effect was exacerbated by the presence of Na+ at a high concentration in the hydrogels. Release and degradation of AA were enhanced at higher soil moisture levels. A complete degradation of AA occurred between 15 and 20 days after incubation (DAI), but it took longer for Na+ concentration to decrease to a safe level. These results indicate that high concentration of both AA and Na+ present in the SAPs inhibits plant growth. The finding of this study may provide a guideline for appropriate application of SAPs in agriculture.

Response of wheat seedlings to Mn‐lignosulfonate adhered to granular NPK

AbstractManganese (Mn) deficiency is a widespread crop micronutrient disorder. The aim of this work was to evaluate two NPK fertilizers coated with Mn that eliminate the specific labor cost for applying Mn and that allow the correction of Mn deficiency in wheat (Triticum aestivum L.). Two Mn sources [MnSO4 and Mn‐lignosulfonate (MnLS)] were compared as NPK coatings at doses of 0.1, 0.3, and 1.0% (w/w) in hydroponic, perlite, and soil pot cultures under growth chamber and greenhouse conditions with wheat to evaluate the effects on dry matter production and Mn concentrations. For the NPK+MnLS product, 52–63% of the total Mn remained in solution at calcareous conditions. However, the NPK+MnSO4 product was able to maintain only 14–25% of the total Mn added in solution. As expected, the MnLS product resulted in higher Mn concentrations in shoots than the MnSO4 product due to the Mn complexation by lignosulfonate which preserved Mn from precipitation and maintained it available for plants. In the experiment with perlite as growth substrate, at low Mn dose (0.1% Mn) a similar Mn concentration in wheat shoots was found (57 mg kg−1 DW for the MnSO4 coating versus 72 mg kg−1 DW for MnLS coating), but at the highest dose (1.0% Mn) the NPK+MnLS showed a significant increase in shoot Mn concentration (167 versus 132 mg kg−1 DW). Soil application of coated NPK products showed similar Mn concentrations in shoots with both Mn sources (29–37 mg kg−1 DW), except for the NPK+MnSO4 (0.1%) treatment (only 18 mg kg−1 DW). Based on the recommended Fe/Mn values (Fe : Mn ratio = 1.5–2.5) given in the literature for plants with a correct nutrition, only the NPK+MnLS (0.3%) fulfilled this ratio (Fe : Mn = 2.5).

Evaluation of Growth Responses in Wheat as Affected by the Application of Zinc and Boron to a Soil Deficient in Available Zinc and Boron

A soil–pot culture experiment was conducted to study the individual and interactive effects of zinc (0, 5, and 10 mg kg−1 soil) and boron (0, 0.75, and 1.5 mg kg−1 soil) on growth, enzymatic activity, nutrient uptake, seed reserve content, and yield in wheat (var. HD2285) in a soil deficient in available zinc and hot water–extractable boron. Although the application of zinc and boron alone significantly increased the plant height, grain yield, total dry-matter yield, tissue zinc, and boron content in maize, maximum increase was obtained with the combined application of zinc and boron. The activities of enzymes peroxidase and starch phosphorylase decreased as compared to untreated control but the activity of carbonic anhydrase increased. Protein, starch, and phytate content of grains also increased with the application of the micronutrients. Moreover, in the absence of zinc, application of boron decreased the starch content of grains.

Elevated CO2 improves root growth and cadmium accumulation in the hyperaccumulator Sedum alfredii

This study examined the effect of elevated CO2 on plant growth, root morphology and Cd accumulation in S. alfredii, and assessed the possibility of using elevated CO2 as fertilizer to enhance phytoremediation efficiency of Cd-contaminated soil by S. alfredii. Both soil pot culture and hydroponic experiments were carried out to characterize plant biomass, root morphological parameters, and cadmium uptake in S. alfredii grown under ambient (350 μL L−1) or elevated (800 μL L−1) CO2. Elevated CO2 prompted the growth of S. alfredii, shoot and root biomass were increased by 24.6–36.7% and 35.0–52.1%, respectively, as compared with plants grown in ambient CO2. After 10 days growth in medium containing 50 μM Cd under elevated CO2, the development of lateral roots and root hairs were stimulated, additionally, root length, surface area, root volume and tip number were increased significantly, especially for the finest diameter roots. The total Cd uptake per pot was significantly greater under elevated CO2 than under ambient CO2. After 60 d growth, Cd phytoextraction efficiency was increased significantly in the elevated CO2 treatment. Results suggested that the use of elevated CO2 may be a useful way to improve phytoremediation efficiency of Cd-contaminated soil by S. alfredii.

Nutrient composition of spent wash and its impact on sugarcane growth and biochemical attributes

Nutrient composition of crude and digested spent wash and effect of their application on sugarcane growth and biochemical attributes were studied. Higher concentrations of essential nutrients (P, S, Fe, Mn, Zn, Cu) and heavy metals (Cd, Cr, Ni and Pb) were present in crude spent wash (CSW) as compared to the digested spent wash (DSW); sulphur content was the highest (765μgml(-1) in DSW and 1,609μgml(-1) in CSW) among all nutrients analyzed. Sugarcane (Saccharum spp. hybrid cultivar CoLk 8102) setts grown in soil pot culture conditions with different rates of crude spent wash (5, 10, 20 and 100mlkg(-1) soil) along with digested spent wash (100mlkg(-1) soil) showed improvement in bud sprouting (10.5%), settling height (40%), root number (9.4%), root length (13.2%), chlorophyll a (52.9%) and b (55.3%) contents and activity of catalase (98%) enzyme over control at low rate of crude spent wash (5mlkg(-1) soil). Whereas, higher doses of spent wash (20 and 100mlkg(-1) soil) decreased these parameters markedly except peroxidase which was found higher at all the levels of both CSW and DSW. Findings indicated stimulatory effect of low rate of crude spent wash (5mlkg(-1) soil) on root and shoot growth and inhibitory effect of higher dose (100mlkg(-1) soil) of both crude and digested spent wash, therefore, judicious application of spent wash will improve crop productivity and alleviate environmental pollution problems.

Effect of heavy metal pollutants on sunflower

The aim of this present study was to assess the tolerance of pollutant elements (Co, Ni, Cd, Cr and Pb) on visible foliar symptoms, tissue concentration and some biochemical parameters in sunflower plants grown at 0.25 mM in soil pot culture. At equimolar concentrations (0.25 mM), Cd induced the most severe visual toxicity effects and exhibited maximum oxidative damage as observed by accumulation of ThioBarbituric Acid Reactive Substances (TBARS) and lower antioxidant capacity than the plants is exposed to Co, Cd, Cr and Pb. The study suggests that the degree of oxidative damage assessed by the manifestation of external visual toxicity effects, tissue concentration and alteration in biochemical parameters were found to be in the order Cd>Cr>Ni>Co>Pb. Key words: Sunflower, visible symptoms, TBARS, antioxidant, tissue concentration.

Acaulospora brasiliensis comb. nov. and Acaulospora alpina (Glomeromycota) from upland Scotland: morphology, molecular phylogeny and DNA-based detection in roots

Spores of two supposedly arbuscular mycorrhizal fungal species, new to the United Kingdom and recently described as Acaulospora alpina and Ambispora brasiliensis (Glomeromycota), were discovered in soil samples from moorland in upland Scotland. Soil and plant trap pot cultures were established, but attempts to establish these fungi in single-species pot cultures with Plantago lanceolata as host were unsuccessful. Nevertheless, based on a 1.5-kb DNA fragment spanning part of the small subunit rRNA gene, the internal transcribed spacer region and part of the large subunit rRNA gene, both these species could be detected directly in field-sampled roots, together with one uncultured species each of Scutellospora, Rhizophagus (former Glomus group Ab, or 'Glomus intraradices clade') and Acaulospora. Whereas A. alpina has characteristic morphological similarities to other species in its genus, A. brasiliensis morphologically has little in common with any other species in Ambispora. The molecular phylogeny, DNA barcoding and morphological evidence clearly place A. brasiliensis in the genus Acaulospora. We therefore rename the species, reported from Brazil and Scotland, as Acaulospora brasiliensis comb. nov., and discuss ecological aspects of the very different environments from which A. brasiliensis and A. alpina have been reported.

A comparison of the effects of drought on proline accumulation and peroxidases activity in leaves of Festuca rubra L. and Lolium perenne L.

The effect of soil drought on leaf water content, proline content, and the activity of guaiacol (GuPX) and ascorbate (APX) peroxidases as well as the level of lipid peroxidation were investigated in leaves of drought resistant red fescue (&lt;em&gt;Festuca rubra&lt;/em&gt;) and drought sensitive perennial ryegrass (&lt;em&gt;Lolium perenne&lt;/em&gt;). Plants were grown under glasshouse conditions in soil pot culture. 26 day-old grasses were exposed to drought by withholding irrigation for 18 days. Water content in leaves of perennial ryegrass decreased more than in red fescue throughout the experimental period. On the other hand, proline content (PC) was higher in red fescue. The activity of APX and GuPX increased in leaves of red fescue, while it did not change in perennial ryegrass. Our data demonstrate that both red fescue and perennial ryegrass were able to survive applied drought, as shown by a lack of stress-induced lipid peroxidation and hence no evidence of oxidative damage. We speculate, that the observed drought stress tolerance at cellular level was associated with the ability to accumulate proline, and to maintain high activity of APX and GuPX, resulting in protection against oxidative damage and lipid peroxidation. It seems that this mechanism works better in red fescue.