Catalase and Phosphatase Activities During Hydrocarbon Removal from Oil-Contaminated Soil Amended with Agro-Industrial By-products and Macronutrients

Microbiological activities are essential in the bioremediation of polluted soils. The enzymatic activities of microorganisms are usually used as a biological indicator of soil health. The aim of this work was to observe the catalase, acid phosphatase (AcP), and alkaline phosphatase (AlP) activities in soil that was amended with agro-industrial by-products and macronutrients during the process of total petroleum hydrocarbon (TPH) removal. To this end, microcosm tests were performed with soil and agro-industrial by-products ratios of 100:2:2, for soil:sugarcane bagasse pith:filter cake mud (SSF); 100:2, for both soil:sugarcane bagasse pith (SS); and for soil filter cake mud (SF). The macronutrients—carbon, nitrogen, and phosphorus—in the experimental treatments were adjusted to 100:10:1 with a solution of NH₄NO₃ and K₂HPO₄. The best TPH removal (51.4%) was obtained with SSF at 15 days. In addition, a significant correlation was observed between TPH removal and AlP as well as AcP (r = 0.74, p < 0.0001; r = 0.70, p < 0.0107, respectively). Fungi growth was also correlated with both AlP (r = 0.97, p < 0.0001) and AcP (r = 0.95, p < 0.0001) activities. Besides, bacterial and fungi growth showed a correlation with TPH (r = 0.86, p < 0.001; r = 0.77, p < 0.0034, respectively). It could be said that the agro-industrial by-products and macronutrients contributed to pollutant removal from the oil-polluted soil at relatively short amount of time. In addition, the enzymatic activities were increased after the treatment; in this study, the high sensitivity enzyme was AlP, and it could be used as an indirect indicator of oil pollutant removal.     

Nuclear and cytoplasmic contributions from <Emphasis Type="Italic">Erianthus arundinaceus</Emphasis> (Retz.) Jeswiet in a sugarcane hybrid clone confirmed through genomic in situ hybridization and cytoplasmic DNA polymorphism

A hybrid between Erianthus arundinaceus (Retz.) Jeswiet and Saccharum spontaneum L. which are wild related species of sugarcane (Saccharum L., Family Poaceae), was repeatedly crossed as female parent with sugarcane commercial varieties to develop near commercial sugarcane clones. The cytoplasm type of the hybrid derivatives were confirmed to be of E. arundinaceus through the mitochondrial and chloroplast DNA polymorphism of nad 4/3-4 intron segment and psbC–trnS segment, respectively. The E. arundinaceus × S. spontaneum hybrid with somatic chromosome number 2n = 62 was confirmed to have 30 chromosomes from E. arundinaceus through genomic in situ hybridization (GISH). The (E. arundinaceus × S. spontaneum) × sugarcane hybrid (2n = 118) had 24 chromosomes from E. arundinaceus whereas its next generation hybrid with sugarcane (2n = 108) had only 12 Erianthus chromosomes. The commercial sugarcane hybrid Co 15015, which is the third generation hybrid with 2n = 106 was confirmed to have two E. arundinaceus chromosomes through GISH. It is the first report of sugarcane with both alien cytoplasm and chromosome contributions from E. arundinaceus.     

Estimation of natural outcrossing rate and genetic diversity in Lima bean (<Emphasis Type="Italic">Phaseolus lunatus</Emphasis> L. var. <Emphasis Type="Italic">lunatus</Emphasis>) from Brazil using SSR markers: implications for conservation and breeding

Lima bean (Phaseolus lunatus L.) is an important food source in Brazil, especially in the northeast region, where its production and consumption are high. The goals of the present study were to estimate natural outcrossing rates and genetic diversity levels of Lima bean from Brazil, using ten microsatellite loci to obtain information for their conservation and breeding. Fourteen accessions were selected from an experiment in field with open-pollinated and with the presence of pollinating insects. Twelve seeds of each of the 14 selected accessions were grown in screenhouse for tissue harvest and DNA extraction. The multilocus model was used to determine the reproductive system. The outcrossing rate was 38.1 % (t_m = 0.381; t_s = 0.078), and the results indicated a mixed mating system with a predominance of selfing (1 ? t_m = 61.9 %). The biparental inbreeding rate was high (t _m  ? t _s  = 0.303) and the multilocus correlated paternity was quite high (r _p(m) = 0.889), indicating that the progeny was mostly composed of full sibs. The average effective number of pollen donors per maternal plant (N _ep ) was low (1.12), and the fixation index for maternal genotypes (F _m ) was 0.945, indicating that most genitors resulted from inbreeding. The studied families presented considerable genetic variability: A = 6.10;  %P = 30; H _e  = 0.60 and H _o  = 0.077. Total diversity was high (H _T = 0.596), and a portion was distributed within families (H _S = 0.058). In addition, diversity was higher between families (D _ST = 0.538), and genetic differentiation was high (G _ST = 0.902). The results presented here can be used in the implementation of Lima bean conservation and breeding programs in Brazil.     

High Zn concentration does not impair biomass,cutting radial growth,and photosynthetic activity traits in <Emphasis Type="Italic">Populus alba</Emphasis> L.

Purpose

Evaluate the efficiency of Populus alba clone Villafranca in the uptake and translocation of Zn from contaminated soils.

Materials and methods

The effects of 48 days of zinc treatment (Zn _t ) on the growth and the photosynthetic activities of P. alba L. clone Villafranca were studied using ZnSO₄ (375 ppm per unit of soil dry weight) added in sand and peat moss substrate at the beginning of the treatment (T ₀) and again after 30 days (T ₁) in order to reach a target Zn concentration of 375 ppm at T ₀ and 750 ppm at T ₁ per unit of soil dry weight.

Results and discussion

Zn uptake in the different organs was analyzed after 30 (T ₁) and 48 days (T ₂) from the beginning of treatment, showing the following order: root ? leaves ≥ woody cutting = stem. The leaf area increased by 12 % in comparison to control plants at the end of second treatment (48 days). Cutting radial growth showed a high synchronicity in the growth rate fluctuation among control and Zn _t plants, but a higher increase in radial diameter of Zn _t cutting was observed starting from day 38 (after 8 days of second Zn _t ) reaching after 48 days 38 % higher than control plants.

Conclusions

Although our data of leaf Zn concentration were in the range usually reported as toxic for plants, Villafranca clone in Zn _t substrate were unaffected in terms of net CO₂ assimilation and stomatal conductance to water vapor.

     

Screening species of <Emphasis Type="Italic">Pilocarpus</Emphasis> (Rutaceae) as sources of pilocarpine and other imidazole alkaloids

Plants of the Pilocarpus genus (Rutaceae) are popularly known as jaborandi and are the only source of pilocarpine, an imidazole alkaloid used in eye-drops for the treatment of glaucoma as well as for the stimulation of sweat and lachrymal glands. Alkaloid extracts from leaf samples of seven species of Pilocarpus, from the states of São Paulo and Maranhão in Brazil, were analyzed using HPLC–ESI–MS/MS. The samples contained between 0.88 ± 0.04 and 1.00 ± 0.14% of alkaloids in relation to the dry weight of their leaves, with significant differences in results (P ≤ 0.05) found only between Pilocarpus microphyllus planted in the state of Maranhão and Pilocarpus spicatus, Pilocarpus trachyllophus, Pilocarpus pennatifolius and Pilocarpus jaborandi; as well as between Pilocarpus spicatus and Pilocarpus racemosus. Pilocarpine was not found in P. spicatus, whereas in the other species it ranged from 2.6 ± 0.1 to 70.8 ± 1.2% of total alkaloids. P. microphyllus planted in the state of Maranhão for pilocarpine extraction had the highest total alkaloid content, but it had only 35% of pilocarpine in relation to total alkaloids. Three other species contained more pilocarpine in relation to total alkaloids: P. jaborandi (70.8%), P. racemosus (45.6%) and P. trachyllophus (38.7%); and could be candidates for pilocarpine extraction. Differences in alkaloid content were significant for all these samples (P ≤ 0.05). Imidazole alkaloids were observed and partially characterized based on their retention times and high resolution mass. The seven species analyzed had different imidazole alkaloid profiles, but only one did not present quantifiable pilocarpine contents in its leaves. The Pilocarpus genus shows potential for the prospection of novel alkaloids.     

Genetic diversity and relationships of wild and cultivated <Emphasis Type="Italic">Zanthoxylum</Emphasis> germplasms based on sequence-related amplified polymorphism (SRAP) markers

The genus Zanthoxylum, belonging to Rutaceae, has a long history of cultivation both for economic and chemical values in China. To effectively conserve and sustainably utilize this genus resource, a study on genetic diversity and relationships of Zanthoxylum germplasms was carried out by employing SRAP markers. We used 16 primer combinations to assess genetic variations and relationships among 175 accessions from eight cultivated provenances, including Shandong, Henan, Shanxi, Shaanxi, Gansu, Sichuan, Guizhou and Yunnan. A total of 145 clear repetitive and intense bands were yielded, and the percentage of polymorphic bands was 100 % for per primer combination, indicating a relatively high diversity among Zanthoxylum germplasms. From a geographic perspective, the highest genetic diversity level was observed within Guizhou provenance (N _a  = 1.97, Ne = 1.52, H = 0.31, I = 0.46) while Henan provenance had the lowest genetic diversity (N _a  = 1.68, Ne = 1.45, H = 0.25, I = 0.37). Based on AMOVA results, the abundant genetic variation was mainly caused by variation of intra-provenances (84.96 %), rather than among provenances (15.038 %). The results indicated low genetic differentiation (G _st  = 0.133) and high gene flow (N _m  = 3.2605) among provenances. The neighbor-joining tree revealed that the 175 accessions could be divided into four groups, and groupings indicated a divergence between the cultivated accessions of Zanthoxylum bungeanum Maxim. and Z. armatum DC. Moreover, three accessions of Z. piperitum DC. var. inerme without prickles introduced from Japan gathered one cluster. Cluster IV is composed of accessions of different geographical origin, including 11 wild species and 10 cultivated accessions of Z. bungeanum. The cluster analysis also reflected a relatively close relationship between the geographical origins and the classification of accessions in cluster I. Structure analysis indicated that collected Zanthoxylum accessions could be divided into two major groups. The information obtained from our research would benefit to make use of Zanthoxylum germplasms and assist the management of a Zanthoxylum germplasms collection.     

Comparative Analysis of Bacteriophages and Bacteria Removal in Soils and Pyrophyllite-Amended Soils: Column Experiments

The objective of the present study was to investigate the transport and removal of Escherichia coli, Bacillus subtilis, Staphylococcus aureus, bacteriophage MS2, and bacteriophage Phix174 in the soils and pyrophyllite-amended soils. Laboratory columns experiments were performed under saturated flow conditions. Our results showed that bacteriophages passed through the soils more easily than bacteria under the given experimental conditions (pulse injection?=?15 min, flow rate?=?0.5 mL/min, column length?=?20 cm, inner diameter?=?2.5 cm, pH?=?7.6, electrical conductivity (EC)?=?150.1 μS/cm); the log removals of bacteria were in the range of 0.44 to 1.72, whereas the log removals of bacteriophages were between 0.01 and 0.13. Our results also demonstrated that the transport of bacteria and bacteriophages in the soil columns could be reduced considerably in the presence of pyrophyllite. Under the same column experimental conditions above, the log removals for MS2 and Phix174 in 50% soil?+?50% pyrophyllite were 2.64 and 3.05, respectively, whereas the log removals in 100% pyrophyllite were 5.70 for MS2 and 5.10 for Phix174; those values were far greater than the log removals in 100% soil (MS2?=?0.063, Phix174?=?0.128). Additional column experiments (step injection, flow rate?=?0.3 mL/min, column length?=?30 cm, inner diameter?=?2.5 cm, solution pH?=?8.4, EC?=?39.8 mS/cm) showed that the log removals for B. subtilis (1.72) and Phix174 (1.48) in the pyrophyllite were greater than those in the soil (B. subtilis?=?1.41; Phix174?=?0.39). This study demonstrated that the pyrophyllite amendment method could be used for protecting groundwater from microbial contamination by animal carcass burial soils.     

Chemical Behavior of U(VI) in the Presence of Soil Components

Soil components from different environments (forest (OF), semiarid (SZ), and sand (AS)) were separated from fulvic and humic substances, characterized by DRX, EDS(SEM), and zero-charge points were determined. The sorption of U(VI) by these materials was determined considering contact time, concentration of U(VI), pH, ionic strength, and presence of sodium chloride and humic acids. The time to reach the kinetic sorption equilibrium was ca. 1 min for the components of the SZ and AS soils, whereas those from OF required longer times. The zero-charge points of the materials indicate that in the experimental conditions, the surfaces of the materials are positively charged, as are uranyl ions. The sorption kinetic data were well fitted to the pseudo-second-order model, which indicates chemical sorption. The maximum sorption capacities for U(VI) obtained from data fitted to the Langmuir model of OF and SZ were 49 and 19.8 mg g^?1 respectively. Sorption isotherm data for AS were best fitted to the Freundlich model (q_e?=?5.4 mg g^?1). The maximum values of distribution coefficients (K_d) were 23?±?7 L kg^?1, 545?±?64 L kg^?1, and 1178?±?229 L kg^?1 for AS, SZ, and OF, respectively; these values may depend on pH, contact time, initial concentration of U(VI), and the composition of the materials. Sodium chloride in the aqueous solutions affects U(VI) sorption by the materials SZ and AS. The effect of humic acids depends on pH, only in acid media soluble humate complexes may be formed.     

Morphological and genetic diversity of shea tree (<Emphasis Type="Italic">Vitellaria paradoxa</Emphasis>) in the savannah regions of Ghana

Vitellaria paradoxa C. F. Gaertn., commonly known as shea tree or Vitellaria, is ranked the most important tree species of the savannah regions in the most African countries due to its ecological and economic importance for livelihoods and national economies. However, the savannah regions are the most vulnerable areas to the global climate change. Moreover, the Vitellaria populations on farmlands are threatened by the dominance of old trees with low or lack of regeneration. In this study both morphological and genetic diversity were assessed using several phenotypic traits and 10 microsatellite markers, respectively, to assess the impact of land use and agro-ecozone types on Vitellaria in Ghana. The land use types were forests and farmlands, and the agro-ecozone types included the Transitional, Guinea, and Sudan savannah zones. The mean values of morphological traits, such as diameter at breast height (DBH) and canopy diameter (CD), were statistically different between forest (DBH = 22.20, CD = 5.37) and farmland (DBH = 39.85 CD = 7.49) populations (P < 0.00001). The Sudan savannah zone with mean petiole length of 4.96 cm showed significant difference from the other zones, likely as a result of adaptation to drier climate conditions. Genetic data analysis was based on 10 microsatellite markers and revealed high genetic diversity of Vitellaria in Ghana: mean expected heterozygosity, H _e was 0.667, and allelic richness, measured as number of effective alleles A _e , was 4.066. Both farmlands and forests were very diverse indicating lack of negative influence of farmer’s selection on genetic diversity. Fixation index was positive for all populations (mean F _IS = 0.136) with farmlands recording relatively higher values than forests in all ecological zone types studied, probably indicating less gene flow in the farmlands. Moderate differentiation (F′ _ST = 0.113) was comparable to other similar tree species. Both land use and ecological zone types influenced genetic differentiation of Vitellaria at varying levels. The species was spatially structured across three ecozones and following climatic gradient. The forest reserves are used in situ conservation for Vitellaria in Ghana. High diversity observed in the most arid zones provides opportunity to find and use appropriate plant materials for breeding climate change resilient trees.     

C-banded karyotype of <Emphasis Type="Italic">Thinopyrum bessarabicum</Emphasis> and identification of its chromosomes in wheat background

C-banded pattern in two accessions of Thinopyrum bessarabicum (Save ex Rayss) A. Löve (2n = 2x = 14, E^bE^b) and their idiogram was established. C-banding analysis was further used to identify the chromosomes of Tritipyrum amphiploid (2n = 6x = 42, AABBE^bE^b) and a BC₁F₂ genotype from wheat and Tritipyrum. Two 18S-26S rDNA loci were detected on Th. bessarabicum chromosomes by in situ hybridization using an 18S-26S rDNA probe. E^b chromosomes in Tritipyrum generally were identified by their distinctive C-banding patterns which reflected heterochromatin regions. C-banding procedure resulted in sharp and distinct bands in one or both ends of E^b chromosomes without interval bands. Observed C-bands in E^b genome mainly reflected the telomeric and subtelomeric sequences which also showed more strong signals in genomic in situ hybridization. Results showed the importance of the C-banding technique as a screening tool in identification of addition and substitution lines in the progenies of wheat and Tritipyrum crosses during segregating generations.     

Earthworm burrowing activity of two non-Lumbricidae earthworm species incubated in soils with contrasting organic carbon content (Vertisol vs. Ultisol)

The aim of this study was to investigate the burrowing activity of two earthworm species: the endogeic Drawida sinica and one undescribed Amynthas species incubated in Vertisol and Ultisol presenting different soil organic C content. Because of their contrasting feeding behaviours, we hypothesised that soil type would have a bigger influence on the burrowing activity of the endogeic than the anecic species. Repacked soil columns inoculated with earthworms for 30 days were scanned using X-ray tomography and the compiled images used to characterise the burrow systems. After scanning, the saturated hydraulic conductivity (K _sat) was also measured. The Amynthas species burrows were less numerous (30 vs. 180), more vertically oriented (57 vs. 37°), more connected from the surface to the bottom of the columns (73 vs. 5 cm³) and had a higher global connectivity index (83 vs. 28%) than those of D. sinica. The K _sat was threefold faster in columns incubated with Amynthas and was linked to the volume of percolating burrows (R ² = 0.81). The soil type did not influence Amynthas burrow characteristics. In contrast, there were 30% more D. sinica burrows in the Vertisol than in the Ultisol while other burrow characteristics were not affected. This result suggests that these burrows were more refilled with casts leading to shorter and discontinuous burrows. The K _sat was negatively related to the number of burrows (R ² = 0.44) but was not statistically different between the Vertisol and the Ultisol, suggesting a constant impact of this species on the K _sat. We found that a decrease in the amount of soil organic C by 50% had only a small influence on earthworm burrowing activity and no effect on the K _sat.     

Assessment of Surface Water Quality in the Big Sunflower River Watershed of Mississippi Delta Using Nonparametric Analysis

Assessment of surface water quality in the Mississippi Delta is essential to quantify the eutrophication of the Gulf of Mexico. This study estimated the characteristics and variations of surface water quality at three study sites in the Big Sunflower River Watershed (BSRW) within the Mississippi Delta using Kruskal-Wallis, Dunn, Mann-Kendall, and Pettitt tests. In general, contents of some water quality constituents such as nitrate-nitrogen (NO₃???N) and total phosphorus (TP) in the BSRW varied from site to site each year, whereas variations of other constituents such as pH and dissolved oxygen (DO) each year were basically not significant. The highest median concentrations were found in spring for NO₃???N and total nitrogen (TN); in summer for specific conductance (SC), Na, and Cl; and in winter for DO. Mann-Kendall trend analysis revealed that there was an increasing annual trend at Leland but a decreasing annual trend at Merigold for NO₃???N concentrations even though such changes were very small, whereas there was no annual trend for TP at any of the three study sites. Pettitt’s test further identified that the NO₃???N concentrations had an abrupt increase in February 2009 at the median value of 0.44 mg L^?1 in Leland and an abrupt decrease in June 2012 at the median value of 3.65 mg L^?1 in Merigold. A very good linear correlation existed between total dissolved solid (TDS) and magnesium (Mg) in the BSRW, which could be used to estimate TDS from Mg concentrations for this watershed when the data for TDS are absent.     

Temporal variations of soil respiration at multiple timescales in a spruce-fir valley forest,northeastern China

Purpose

There is a paucity of data regarding the multiple timescale variations of heterotrophic respiration (R _H) and autotrophic respiration (R _A) as well as the primary controlling factors. The objective of this study is to find the temporal variations of total soil respiration (R _S) and its components, revealing the driving factors at different timescales.

Materials and methods

A trenching method was used to distinguish R _S, R _H, and R _A in a spruce-fir valley forest in northeastern China. We used the closed dynamic chamber method to measure the soil respiration rate. Analyses of R _S, R _H, and R _A in relation to biotic and abiotic factors were conducted to realize the temporal variations at different timescales.

Results and discussion

Only R _S and R _H showed a distinct diurnal variation and soil temperature (T _S) can explain 68 and 59 % of the daily variation, respectively. R _S, R _H, and R _A showed a pronounced, single peak curve seasonally, and T _S can explain 11–95 % of the seasonal variation. Soil moisture (W _S) maintained at a relatively high level and was not related to R _S, R _H, or R _A on a seasonal scale, and there was no significant relationship between the seasonal R _S, R _A, and root biomass. However, for 5 years, only the mean R _A of the growing season was significantly related to the mean W _S, which can explain 39 % of the inter-annual variation of R _A. The annual variations of litterfall and the relative growth rate of stems were not related to R _S, R _H, or R _A. The contribution of R _H to R _S was larger, and the temperature sensitivity was 2.01–3.71 for R _S, 1.90–3.08 for R _H, and 2.20–5.65 for R _A.

Conclusions

R _S, R _H, and R _A show different temporal variations at multiple timescales. When W _S is not restricted, T _S is the primary driving factor of daily and seasonal variation of R _S and R _H. In this site, R _H accounts for a large proportion of R _S and plays a crucial role in determining the magnitude and temporal variation of R _S.

     

Effects of cover crop in an apple orchard on microbial community composition,networks, and potential genes involved with degradation of crop residues in soil

Changes in the soil microbial communities and networks were monitored after planting the cover crop for 9 years. The field experiment included plots with a cover crop and without a cover crop but with weed control, and two subplots with or without chemical fertilizer (192 kg N ha^?1, 108 kg P₂O₅ ha^?1, and 168 kg K₂O ha^?1 each year). After applying the cover crop and chemical fertilizer for 9 years, the composition and activity of bacterial and fungal communities changed significantly (p?<?0.05), with the cover crop had greater effects than the chemical fertilizer on the composition of the soil microbial community. The relative abundances of 22 selected genera (in Firmicutes and Bacteroidetes) and two selected classes (Ascomycota) related to cover crop residue degradation increased significantly in the presence of the cover crop (p?<?0.05). Network analysis showed that the cover crop decreased the number of positive links between bacterial and fungal taxa by 25.33%, and increased the negative links by 22.89%. The positive links among bacterial taxa increased by 16.63% with the cover crop, mainly among Proteobacteria (increase of 39), Firmicutes (16), Actinobacteria (five), and Bacteroidetes (10). The links among fungal taxa were less than among bacterial taxa and were not significantly affected by cover crop. Taxa such as Thaumarchaeota, unidentified_Nitrospiraceae, unidentified_Nitrosomonadaceae, Faecalibacterium, Coprococcus_3, and Ruminococcaceae_NK4A214_group dominated the network without the cover crop but they were not dominant with the cover crop. The relative abundances of potential genes involved with the degradation of cellulose, hemicellulose, and cello-oligosaccharides increased significantly with the cover crop. Therefore, the SOC and TN contents were enhanced by the cover crop with the increase of the soil enzyme activities. Thus, the apple yield was improved by the cover crop.     

A Comparative Study on Removal Efficiency of Cr(VI) in Aqueous Solution by <Emphasis Type="Italic">Fusarium</Emphasis> sp. and <Emphasis Type="Italic">Myrothecium</Emphasis> sp.

Environmental pollution with chromium is due to residues of several industrial processes. Bioremediation is an alternative actually considered to remove Cr (VI) from the environment, using adapted organisms that grow in contaminated places. Have been conducted studies with fungi mechanisms of interaction with chromium, most of which have focused on processes biosorption, characterized it by passive binding of metal components of the cell surface, and bioaccumulation, wherein the metal entry to cells occurs with energy expenditure. The paper presents the results of studies carried out on sorption of chromium (VI) ions from aqueous solutions by Fusarium sp. and Myrothecium sp. Both biomasses have the ability to take up hexavalent chromium during the stationary phase of growth and as well inactive conditions. Fusarium sp. showed 26% of biosorption with active biomass and 64% in inactive biomass; meanwhile, Myrothecium sp. obtained 97 and 82%, respectively. Both fungi showed adjust to pseudo-second-order model in active (Fusarium sp. R ² = 0.99; Myrothecium sp. R ² = 0.96) and inactive biomass assay (Fusarium sp. R ² = 0.99; Myrothecium sp. R ² = 0.99). The data of the active biomass test also confirmed to the intraparticle diffusion model (Fusarium sp. R ² = 0.98; Myrothecium sp. R ² = 0.93). The results obtained through this investigation indicate the possibility of treating waste effluents containing hexavalent chromium using Fusarium sp. and Myrothecium sp.     

Genetic diversity of a <Emphasis Type="Italic">Coffea</Emphasis> Germplasm Collection assessed by RAPD markers

Genetic diversity and relationships within and among nine species of Coffea, one species of Psilanthus and the Piatã hybrid from the Coffee Germplasm Collection of Instituto Agronômico de Campinas (IAC), Brazil were assessed using RAPD markers. Genetic diversity and relationships were evaluated by proportion of polymorphic loci (P), Shannon’s genetic index (H′ and G′_ST) and clustering analysis. The overall RAPD variation among all accessions was mostly partitioned between rather than within species. However, C. canephora and C. liberica showed a high genetic diversity within the species (\({\underline{\hbox{H}'}} \) _sp = 0.414 and \({\underline{\hbox{H}'}} \) _sp = 0.380, respectively) and this was highly structured (high \({\underline{\hbox{G}'}} \) _ST). Genetic diversity from C. congensis and C. arabica was also structured, but with lower levels of genetic diversity (\({\underline{\hbox{H}'}} \) _sp = 0.218 and \({\underline{\hbox{H}'}} \) _sp = 0.126, respectively). The results were consistent with agronomic and molecular studies and demonstrated that the IAC Coffea Collection is representative of the phylogenetic structure observed in the genera. This study devises sampling strategies for coffee germplasm collections and provides genetic diversity parameters for future comparisons among them.     

Taxon-specific responses of soil microbial communities to different soil priming effects induced by addition of plant residues and their biochars

Purpose

This work investigated changes in priming effects and the taxonomy of soil microbial communities after being amended with plant feedstock and its corresponding biochar.

Materials and methods

A soil incubation was conducted for 180 days to monitor the mineralization and evolution of soil-primed C after addition of maize and its biochar pyrolysed at 450 °C. Responses of individual microbial taxa were identified and compared using the next-generation sequencing method.

Results and discussion

Cumulative CO₂ showed similar trends but different magnitudes in soil supplied with feedstock and its biochar. Feedstock addition resulted in a positive priming effect of 1999 mg C kg^?1 soil (+253.7 %) while biochar gave negative primed C of ?872.1 mg C kg^?1 soil (?254.3 %). Linear relationships between mineralized material and mineralized soil C were detected. Most priming occurred in the first 15 days, indicating co-metabolism. Differences in priming may be explained by differences in properties of plant material, especially the water-extractable organic C. Predominant phyla were affiliated to Acidobacteria, Actinobacteria, Chloroflexi, Gemmatimonadetes, Firmicutes, Planctomycetes, Proteobacteria, Verrucomicrobia, Ascomycota, Basidiomycota, Blastocladiomycota, Chytridiomycota, Zygomycota, Euryarchaeota, and Thaumarchaeota during decomposition. Cluster analysis resulted in separate phylogenetic grouping of feedstock and biochar. Bacteria (Acidobacteria, Firmicutes, Gemmatimonadetes, Planctomycetes), fungi (Ascomycota), and archaea (Euryarchaeota) were closely correlated to primed soil C (R ²?=??0.98, ?0.99, 0.84, 0.81, 0.91, and 0.91, respectively).

Conclusions

Quality of plant materials (especially labile C) shifted microbial community (specific microbial taxa) responses, resulting in a distinctive priming intensity, giving a better understanding of the functional role of soil microbial community as an important driver of priming effect.

     

Diverse morphological and cytogenetic variation and differentiation of the two subspecies in <Emphasis Type="Italic">Aegilops geniculata</Emphasis> Roth,a wild relative of wheat

Aegilops geniculata Roth, a wild relative of wheat (2n = 4x = 28, genome UUMM), is distributed over the Mediterranean basin and nearby areas. The species consists of two subspecies, subsp. geniculata and subsp. gibberosa (Zhuk.) Hammer. The former is distributed over the whole species area and has been genetically analyzed, and the latter is endemic to Spain and North Africa and has not been genetically evaluated. In this study, to clarify the genetic variation and delineation of the two subspecies from a biosystematic viewpoint, morphological variation among 23 accessions of subsp. geniculata and three of subsp. gibberosa and chromosome pairing at meiosis and fertility in their intra- and inter-subspecific F₁ hybrids were examined. A principal component analysis based on the 11 spike characteristics clearly divided the 26 accessions into two groups representing the two subspecies. The inter-subspecific F₁ hybrids showed significantly lower frequencies of chromosome pairing, significantly higher frequencies of multivalents, and significantly lower fertilities relative to those of the intra-subspecific F₁ hybrids. It was concluded that wide-ranging cytogenetic variation is included in subsp. geniculata, that subsp. gibberosa, the intra-subspecific variation of which is small, is morphologically and cytogenetically differentiated from subsp. geniculata beyond the range of the intra-subspecific variation of subsp. geniculata, and that the two subspecies are effectively isolated reproductively by hybrid sterility. The results strongly suggested that western North Africa is one of the important diversity centers of Ae. geniculata, where two subspecies were differentiated in the past and grow together in the present.     

Effect of Cadmium Stress on Growth and Electrical Impedance Spectroscopy Parameters of <Emphasis Type="Italic">Cotinus coggygria</Emphasis> Roots

The use of plants for ecological remediation is an important method of controlling heavy metals in polluted land. Cotinus coggygria is a landscape plant that is used extensively in landscaping and afforestation. In this study, the cadmium tolerance level of C. coggygria was evaluated using electrical impedance spectroscopy (EIS) to lay a theoretical foundation for broad applications of this species in Cd-polluted areas and provide theoretical support to broaden the application range of the EIS technique. Two-year-old potted seedlings of C. coggygria were placed in a greenhouse to analyse the changes in the growth, water content and EIS parameters of the roots following treatment with different Cd concentrations (50, 100, 200, 500, 1000 and 1500 mg kg^?1), and soil without added Cd was used as the control. The roots grew well following Cd treatments of 50 and 100 mg kg^?1. The Cd contents increased with the increase in Cd concentration in the soil. However, the lowest root Cd content was found at 4 months of treatment. The extracellular resistance r_e and the intracellular resistance r_i increased first overall and then decreased with the increasing Cd concentration, and both parameters increased with a longer treatment duration. The water content had a significant negative correlation with the Cd content (P?<?0.01) and the r_e (P?<?0.05). C. coggygria could tolerate a soil Cd concentration of 100 mg kg^?1. There was a turning point in the growth, water content and EIS parameters of the C. coggygria roots when the soil Cd concentration reached 200 mg kg^?1. The root water content and r_e could reflect the level of Cd tolerance in C. coggygria.     

Spatial variation of soil respiration in a coastal protection forest in southeastern China

Purpose

Forest soil respiration is an important component of global carbon budgets, but its spatial variation is inadequately understood. This research aimed to measure soil respiration (R _s), soil water content (M _s-5), soil temperature (T), and carbon dioxide (M _co2) in a coastal protection forest (CPF), which is one kind of man-made forests designed for coastal protection primarily along the coast in China, to determine the relationships among them, and to analyze their spatial distributions in a small scale.

Materials and methods

We measured R _s, M _s-5, T, and M _co2 of 100 plots in an approximately flat grid (totally 4 hm²) by LI-8100A in a Casuarina equisetifolia L. forest on a state-owned forest farm of 326 hm² in SE China. Traditional statistics and geo-statistics including semivariance, Moran’s I index, and fractal dimension were used to analyze data.

Results and discussion

Key findings were that (1) the spatial mean of R _s, M _s-5, T, and M _co2 were 1.194 μmol m^?2 s^?1, 11.387 mmol mol^?1, 14.153 °C, and 407.716 ppm, respectively, in the forest; (2) the relationship between soil respiration and the other three factors was weak, while M _s-5, T, and M _co2 have strong relationships with each other; and (3) the four factors, especially soil respiration, had strong autocorrelation within given limits and showed great heterogeneity with 95 % confidence intervals around the means in the study area, all of which can provide important value for the study of carbon cycling and for the sustainable management of coastal protection forests.

Conclusions

According to geo-statistical analysis and field investigations, soil respiration in the coastal forest is less than in some broad-leaf forests but higher than in some conifers. Strong heterogeneity and autocorrelation are clear; however, its relation with other three factors is weak. CPF is a considerable potential forest for carbon conservation if it is well managed.