Long-term tree growth rate,water use efficiency,and tree ring nitrogen isotope composition of <Emphasis Type="Italic">Pinus massoniana</Emphasis> L. in response to global climate change and local nitrogen deposition in Southern China

Purpose  

We aimed to investigate long-term tree growth rates, water use efficiencies (WUE), and tree ring nitrogen (N) isotope compositions (δ¹⁵N) of Masson pine (Pinus massoniana L.) in response to global climate change and local N deposition in Southern China.     

Putative Role of <Emphasis Type="Italic">Flavobacterium</Emphasis>, <Emphasis Type="Italic">Dokdonella</Emphasis> and <Emphasis Type="Italic">Methylophilus</Emphasis> Strains in Paracetamol Biodegradation

Paracetamol, the most widely and globally used analgesic and antipyretic, is easily accumulated in aquatic environments. In the present study, the biodegradation of paracetamol in different media (one for general growth, one specific for sulfate reducing bacteria, a mineral salts medium and municipal wastewater) inoculated with two types of sludge (from anaerobic lagoon and from oxidation ditch) under different oxygenic conditions (anoxic; moderate oxygenation in open flasks and high oxygenation by aeration) was investigated. In addition, bacteria with relative abundances increasing simultaneously with paracetamol degradation, when this drug was the only carbon source, thus with a putative role in its degradation, were identified using 16S rRNA gene sequences. The results show that aerobic microorganisms had a major role in the degradation of paracetamol, with 50 mg/L totally removed from municipal wastewater after 2 days incubation with aeration, and that the metabolites 4-aminophenol and hydroquinone plus one compound not identified in this work were produced in the process. The identification of bacteria with a role in the degradation of paracetamol revealed a strain from genus Pseudomonas with the highest final relative abundance of 21.2%, confirming previous works reporting strains of this genus as paracetamol decomposers. Besides, genera Flavobacterium, Dokdonella and Methylophilus were also in evidence, with initial relative abundances of 1.66%, 1.48 and 0.00% (not detected) in the inoculum and 6.91%, 3.80 and 3.83% after incubation, respectively. Therefore, a putative role of these genera in paracetamol biodegradation is suggested for the first time.

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Graphical Abstract ?

     

Niche partition of phenanthrene-degrading bacteria along a <Emphasis Type="Italic">Phragmites australis</Emphasis> rhizosphere gradient

The rhizosphere is a critical interface for pollutant remediation in soils. Association between biodegradation of organic pollutants and spatial pattern of degraders along the rhizosphere gradient is, however, still unclear. This study investigated the phenanthrene-degrading bacterial consortia in a Phragmites australis rhizosphere using DNA-stable isotope probing (DNA-SIP). The relative abundance of Sphingomonadales in the ¹³C-labeled consortia decreased with the distance from roots, suggesting that its contribution in phenanthrene degradation was decreased with the distance from roots. Conversely, the relative abundance of Rhizobiales, Rhodobacterales, Lactobacillales, and Enterobacteriales in ¹³C-labeled consortia increased with the distance from roots, suggesting that their contributions in phenanthrene degradation were increased with the distance from roots. The linkage numbers of bacterial species in the co-occurrence network increased with the percentages of ¹³C-labeled reads, suggesting the critical role of syntrophic interactions for phenanthrene degraders. These results suggest the niche partition of phenanthrene degraders, which leaded to the non-linear variation of phenanthrene degradation rates along the rhizosphere gradient. These findings will help us to better understand rhizo degradation of organic pollutants and optimize bioremediation technology by achieving a trade-off among different degraders.     

Exploitation of <Emphasis Type="Italic">Malus</Emphasis> EST-SSRs and the utility in evaluation of genetic diversity in <Emphasis Type="Italic">Malus</Emphasis> and <Emphasis Type="Italic">Pyrus</Emphasis>

A total of 8117 suitable SSR-contaning ESTs were acquired by screening from a Malus EST database, among which dinudeotide SSRs were the most abundant repeat motif, within which, CT/TC followed by AG/GA were predominant. Based on the suitable sequences, we developed 147 SSR primer pairs, of which 94 pairs gave amplifications within the expected size range while 65 pairs were found to be polymorphic after a preliminary test. Eighteen primer pairs selected randomly were further used to assess genetic relationship among 20 Malus species or cultivars. As a result, these primers displayed high level of polymorphism with a mean of 6.94 alleles per locus and UPGMA cluster analysis grouped twenty Malus accessions into five groups at the similarity level of 0.6800 that were largely congruent to the traditional taxonomy. Subsequently, all of the 94 primer pairs were tested on four accessions of Pyrus to evaluate the transferability of the markers, and 40 of 72 functional SSRs produced polymorphic amplicons from which 8 SSR loci selected randomly were employed to analyze genetic diversity and relationship among a collection of Pyrus. The 8 primer pairs produced expected bands with the similar size in apples with an average of 7.375 alleles per locus. The observed heterozygosity of different loci ranged from 0.29 (MES₉₆) to 0.83 (MES₁₃₈), with a mean of 0.55 which is lower than 0.63 reported in genome-derived SSR marker analysis in Pyrus. The UPGMA dendrogram was similar to the previous results obtained by using RAPD and AFLP markers. Our results showed that these EST-SSR markers displayed reliable amplification and considerable polymorphism in both Malus and Pyrus, and will contribute to the knowledge of genetic study of Malus and genetically closed genera.     

<Emphasis Type="Italic">Ziziphus </Emphasis><Emphasis Type="Italic">spina-christi</Emphasis> (L.) Willd.: a multipurpose fruit tree

Neglected and underutilized species often play a vital role in securing food and livestock feed, income generation and energy needs of rural populations. In spite of their great potential little attention has been given to these species. This increases the possibility of genetic erosion which would further restrict the survival strategies of people in rural areas. Ziziphus spina-christi is a plant species that has edible fruits and a number of other beneficial applications that include the use of leaves as fodder, branches for fencing, wood as fuel, for construction and furniture making, and the utilization of different parts e.g. Fruits, leaves, roots and bark in folk medicine. Moreover, the plant is adapted to dry and hot climates which make it suitable for cultivation in an environment characterized by increasing degradation of land and water resources. Lack of research in Z. spina-christi hinders its successful improvement and promotion. Therefore, studies are needed to fully exploit this species. This article aims at summarizing information on different aspects of Z. spina-christi to stimulate interest in this crop which is of importance in Sudan and other countries of the semi-arid tropics.

Effect of <Emphasis Type="Italic">Eucalyptus</Emphasis> forests on understory vegetation and soil quality

Purpose

Eucalyptus forest plantations are normally devoid of understory vegetation that is often assumed to be associated with Eucalyptus allelopathic effects. The objective of this study was to determine the influence of high soil compaction and low soil moisture content on inhibition of the germination of understory seeds in Eucalyptus forests and thus would result in the scarcity of understory vegetation.

Materials and methods

The soil water content above the depth of 1 m of six major understory vegetation types was analyzed to determine if there was a correlation between soil water content and understory vegetation. The effects of soil treatment (soil-loosening vs. no soil-loosening) and water supply amount (2500, 2000, 1500, 1000, 500, 250, or 0 ml of water per day) on the seed germination rate of Stylosanthes sp. were explored using an artificial climate chamber experiment. Influence of soil source (five Eucalyptus forest soils vs. two non-Eucalyptus forest soils) and water supply (0, 50, 150, 200, or 400 ml of water every day) on the germination rate of five types of seed were assessed using a three-factor analysis of variance (ANOVA).

Results and discussion

Soil-loosening and water supply significantly (P?<?0.05) increased seed germination rate with the contribution rates of 26.14 and 42.93 %, respectively. Analysis of variance for three-factor experiments revealed a significant (P?<?0.05) effect of water supply and vegetation seed type on the germination rate of plant seeds. No significant effect of soil type was observed on germination rate, indicating that germination rate was not affected by soils in Eucalyptus forest.

Conclusions

The conservation of soil characteristics, such as water content and compaction, during the development of a Eucalyptus forest plantation may be an effective strategy for encouraging the growth of understory vegetation. This study highlights the importance that in dry areas or areas prone to long-term drought, it would be preferable to retain native vegetation.

     

DNA markers and pollen morphology reveal that <Emphasis Type="Italic">Praecitrullus fistulosus</Emphasis> is more closely related to <Emphasis Type="Italic">Benincasa hispida</Emphasis> than to <Emphasis Type="Italic">Citrullus</Emphasis> spp.

The round melon Praecitrullus fistulosus (Stocks) Pangalo has been cultivated in Asia since ancient times and has been considered an underexploited crop in the western world. In the USA, there is an increased interest in using P. fistulosus as a commercial vegetable, and possibly as a rootstock for grafting watermelon, melon, or cucumber. However, the taxonomic classification of P. fistulosus is incomplete and for many years it has been considered a close relative of watermelon [Citrullus lanatus subsp. vulgaris (Schrad. ex Eckl. et Zeyh.) Fursa] and was previously classified as Citrullus lanatus subsp. fistulosus (Stocks) Duthie et J.B. Fuller. Here, we used two sets of DNA markers to assess the genetic similarity of P. fistulosus in relation to Citrullus spp. {including Citrullus lanatus subsp. vulgaris, C. lanatus subsp. lanatus, Citroides group [also known as C. lanatus (Thunb.) Matsum. et Nakai subsp. lanatus var. citroides (Bailey) Mansf. ex Greb.], and C. colocynthis (L.) Schrad.}, Cucumis spp. (including C. melo, C. sativus, C. anguria, C. meeusei, C. zeyheri), Benincasa hispida (Thunb.) Cogn., Lagenaria siceraria (Mol.) Standl. and Cucurbita spp. (including C. moschata Duchesne and the winter squash C. maxima Duchesne). The first marker set comprised 501 markers that were produced by 38 primer pairs derived from watermelon expressed sequenced tags (ESTs) containing simple sequence repeat (SSR) motifs (designated as EST-SSR primers; produced 311 markers), and by 18 primer pairs derived from ESTs that do not contain SSR motives (designated here as EST-PCR primers; produced 190 markers). The second marker set comprised 628 markers that were produced by 18 sequence related amplified polymorphism (SRAP) primer pairs. The phylogenetic data indicated that among these cucurbit species, the wax gourd B. hispida is the closest to the P. fistulosus. Pollen observations, using light microscopy, indicated that each of the cucurbit genera examined here has unique pollen morphology. The Cucurbita spp. have globular pollen grains with a stigmatic surface. The L. siceraria has polygonal pollen grains with symmetrical boundaries, while the Citrullus spp. and Cucumis spp. have ovular (conical) and triangular shaped pollen grains (respectively). The B. hispida and P. fistulosus have spherical or semispherical pollen grains. These pollen features appear to be in agreement with the phylogenetic relationships of these two species based on DNA markers. Analysis with 12 SRAP primer pairs revealed low genetic diversity among 18 United States Plant Introductions (PIs) of P. fistulosus, indicating the need to expand the germplasm collection of this cucurbit crop.     

Comparative Study of Common Bean (<Emphasis Type="Italic"> Phaseolus vulgaris</Emphasis>L.) Landraces Conserved <Emphasis Type="Italic">ex situ</Emphasis> in Genebanks and <Emphasis Type="Italic">in situ</Emphasis> by Farmers

Genetic diversity of populations stored ex situ or in situ can be altered due to the management practices they are subjected to. In this paper, we compare populations of two common bean (Phaseolus vulgaris L.) landraces grown on farms with material collected from the same farms and now kept in two ex situ collections (CIAT and REGEN) with the purpose to monitor any changes that have occurred due to ex situ conservation. The diversity was measured using seven bean microsatellite markers. Further phenotypic and developmental traits were registered in a field experiment. Compared with the in situ populations, the ex situ ones had a lower level of gene diversity and we suggest that this is due to the regeneration process. Most of the phenotypic traits did not differ significantly between ex situ and in situ populations, although for yield and 100-seed weight, the CIAT material showed significant lower values. We assume that these populations have gone through an adaptational change. Overall, the conservation ex situ has been successful in maintaining the majority of the adaptations found in the landraces studied, however, the probable loss of genetic diversity that we have observed, suggest that protocols for the regeneration process must be carefully worked out if the majority of alleles are to be preserved for the future. This study also highlights the complementarity of ex situ and in situ conservation methods in order to preserve landrace adaptations and to capture new, useful diversity generated in in situ populations.     

A significant proportion of indigenous rhizobia from India associated with soybean (<Emphasis Type="Italic">Glycine max</Emphasis> L.) distinctly belong to <Emphasis Type="Italic">Bradyrhizobium</Emphasis> and <Emphasis Type="Italic">Ensifer</Emphasis> genera

The diversity among 269 rhizobia isolated from naturally occurring root nodules of soybean collected from two different agro-ecological regions of India, based on RFLP and sequences of the intergenic spacer (IGS) between the 16S and 23S rRNA genes, growth rate, and indole acetic acid production, revealed their significant, site-dependent genomic diversity. Among these bacteria, nine IGS genotypes were identified with two endonucleases. They were distributed into five divergent lineages by sequence analysis of each IGS representative strain, i.e., (1) comprising IGS genotypes I, II, III, and reference Bradyrhizobium yuanmingense; (2) with genotype IV and strains of unclassified bradyrhizobia genomic species; (3) including genotypes V, VI, and Bradyrhizobium liaoningense; (4) with IGS genotype VII and Bradyrhizobium elkanii strains; and (5) comprising IGS genotypes VIII, IX, and different Ensifer genus bacteria. Host-specificity test revealed that all rhizobia-nodulated soybean and cowpea and only part of them formed nodules on Arachis hypogeae and Cajanus cajan. The great diversity of soybean nodulators observed in this study emphasises that Indian soil is an important reservoir of nitrogen-fixing rhizobia.     

Morphological variation in <Emphasis Type="Italic">Laelia anceps</Emphasis> subsp. <Emphasis Type="Italic">dawsonii</Emphasis> f. <Emphasis Type="Italic">chilapensis</Emphasis> Soto-Arenas Orchidaceae in traditional home gardens of Chilapa,Guerrero, Mexico

Calaverita an endangered Mexican orchid is one of the most elegant and showy orchids of the genus Laelia and essential symbol within the local traditional celebrations of the Day of the Dead, in the region of Chilapa-Guerrero. We investigated morphological variation in flowers of la calaverita (Laelia anceps Lind. subsp. dawsonii (J. Anderson) Rolfe f. chilapensis Soto-Arenas, Orchidaceae) using the labellum of the specimens cultivated in traditional home gardens in the region of Chilapa, Guerrero, Mexico. The use of morphometric traits of the labellum is useful in appraising infra-subspecific morphological variation within the chilapensis form. Floral morphological variation exists among the specimens examined. These specimens, found exclusively in traditional home gardens, were grouped into four morphotypes: NAT, Topiltepec, Xulchuchío, and Terrero. The study of variation of la calaverita revealed the existence of four local morphotypes that originated from a long and complex process of selection of traits which responds to traditional preferences and knowledge about specific biotic and agroecological conditions. The cultural and aesthetic influence of traditional homegarden owners in the Chilapa region acts directly on selection, use and conservation of the morphological traits of la calaverita.     

Diversity of <Emphasis Type="Italic">Citrus</Emphasis><Emphasis Type="Italic">depressa</Emphasis> Hayata (Shiikuwasha) revealed by DNA analysis

Citrus depressa Hayata is an indigenous mandarin species on the Ryukyu Islands located in the subtropical region of Japan. We deduced its phylogenetic relationships by evaluating accessions grown on various Ryukyu Islands via cleaved amplified polymorphic sequence analysis of cpDNA and sequence-related amplified polymorphism (SRAP). The cpDNA results indicated that C. depressa could be classified into two types. SRAP revealed patterns of diversity within C. depressa consistent with our cpDNA results. These results indicate that maternal origin may influence or is correlated with the constitution of the nuclear genome of C. depressa. Another Japanese mandarin species, Citrus tachibana (Makino) Tanaka was distinguished from C. depressa by SRAP markers. Moreover, both C. depressa and C. tachibana could be distinguished from other Citrus species. Our results suggest that Japanese mandarin possesses a characteristic genome with the genus Citrus.     

Perspectives of Quantitative Risk Assessment Studies for <Emphasis Type="Italic">Giardia</Emphasis> and <Emphasis Type="Italic">Cryptosporidium</Emphasis> in Water Samples

A quantitative microbial risk assessment method can be used to evaluate infections probabilities for microorganisms in a specific place. The methodology provides suitable information to generate strategies focusing on health problems. Giardia cysts (GC) and Cryptosporidium oocysts (CO) are considered emerging pathogens that can infect human and animals by ingesting contaminated food or water, where food and water are transport vehicles for these parasites. Studies for GC and CO have reported occurrences for these parasites in water up to 100%, and some of these studies documented a number of cases, about 403,000 people, infected worldwide. This review is focused on compiling the most relevant works assessing the risk for GC and CO and their presence in different water samples that are susceptible for direct and indirect human consumption. The annual risk infection probability for these parasites has been reported from different water sources, with a range between 1 × 10^?6 and 1, while the world standard regulation is 1 × 10^?4. The infection probability depends not only on water quality but also on water treatment implementations.     

Forest-growing properties of soils under young Siberian stone pine (<Emphasis Type="Italic">Pinus sibirica</Emphasis>) forests in Western Siberia

The results of studying the forest-growing properties of the iron-illuvial podzols under purposefully formed young Siberian stone pine (Pinus sibirica L.) forests are presented. The sufficient supply of these stands with moisture and the high content of nitrogen in the soils make the soils favorable for the regeneration, growth, and development of dark coniferous forests. The soils of the test objects exposed to sanitary cutting were compared to those under the control stand. The silvicultural procedures were shown to promote more efficient use of the soil resources by Siberian pine trees.     

A new mycorrhizal helper bacterium, <Emphasis Type="Italic">Ralstonia</Emphasis> species,in the ectomycorrhizal symbiosis between <Emphasis Type="Italic">Pinus thunbergii</Emphasis> and <Emphasis Type="Italic">Suillus granulatus</Emphasis>

In a Robinia-pseudoacacia-dominated coastal forest in Tottori prefecture Japan, the growth and survival of Pinus thunbergii seedlings and the natural regeneration of P. thunbergii was disturbed by R. pseudoacacia. In order to improve the growth of P. thunbergii seedling in the Tottori sand dune, we tried to find a mycorrhiza helper bacteria (MHB) from P. thunbergii mycorrhizosphere in a Tottori sand dune. Two MHB, Ralstonia sp. and Bacillus subtilis, were selected from the nine bacterial species isolated from the mycorrhizosphere of P. thunbergii. The bacterial effect on the ectomycorrhizal fungus Suillus granulatus was investigated by confrontation assay and a microcosm experiment. The confrontation assay showed that Ralstonia sp. promoted the hyphal growth of S. granulatus. Moreover, the S. granulatus–P. thunbergii symbiosis was significantly stimulated by Ralstonia sp. and B. subtilis. Ralstonia sp. and B. subtilis were regarded as MHB associated with P. thunbergii. This is the first report of Ralstonia sp. as an MHB.     

Effects of fire-derived charcoal on soil properties and seedling regeneration in a recently burned <Emphasis Type="Italic">Larix gmelinii</Emphasis>/<Emphasis Type="Italic">Pinus sylvestris</Emphasis> forest

Purpose  

Fire is a primary form of disturbance in boreal ecosystems. Charcoal is an important by-product of forest fire and has been reported to have the potential to influence the plant community establishing after fire. To date, however, no study has effectively tested the relationship between charcoal and plant regeneration in the actual post-fire forests. To determine the contribution of charcoal to soil properties and plant regeneration after forest fires, we conducted in situ investigations concerning the relationship between charcoal and the plant–soil system.     

Production and cytogenetics of trigeneric hybrid involving <Emphasis Type="Italic">Triticum</Emphasis>, <Emphasis Type="Italic">Psathyrostachys</Emphasis> and <Emphasis Type="Italic">Secale</Emphasis>

Trigeneric hybrids may help establish evolutionary relationships among different genomes present in the same cellular-genetic background, and also offers the possibility to transfer different alien characters into cultivated wheat. In this study, a new trigeneric hybrid involving species from the Triticum, Psathyrostachys and Secale was synthesized by crossing wheat-P. huashanica amphiploid (PHW-SA) with wheat-S. cereale amphiploid (Zhongsi 828). The crossability of F₁ hybrid was high with 35.13%, and the fertility was 41.95%. The morphological characteristics of F₁ plants resembled the parent Zhongsi 828. The trigeneric hybrids pollen mother cells (PMCs) regularly revealed averagely 19.88 univalents, 9.63 ring bivalents, 3.97 rod bivalents, 0.60 trivalents and 0.03 tetravalents per cell. Multivalents consisted of trivalents and tetravalents can be observed in 52.7% of cells. A variation of abnormal lagging chromosome, micronuclei and chromosome bridge were formed at anaphase I and telophase II. The mean chromosomes number of F₂ progenies was 2n = 46.13, and the distribution range was 42–53. GISH results revealed that most F₂ plants had 6–12 S. cereale chromosomes, and only 0–2 P. huashanica chromosomes were detected. The results indicated that S. cereale chromosomes can be preferentially transmitted in the F₂ progenies of trigeneric hybrid than P. huashanica chromosomes. A survey of disease resistances revealed that the stripe rust resistance from the PHW-SA were completely expressed in the F₁ and some F₂ plants. The trigeneric hybrid could be a useful bridge for the transference of P. huashanica and S. cereale chromatins to common wheat.     

Microbial inoculation of seeds characteristically shapes the rhizosphere microbiome in <Emphasis Type="Italic">desi</Emphasis> and <Emphasis Type="Italic">kabuli</Emphasis> chickpea types

Purpose

Chickpea is generally cultivated after seed treatment with host-specific Mesorhizobium ciceri, the nitrogen-fixing bacterium forming root nodules. Some species of free-living cyanobacteria are capable of nitrogen fixation. We examined the rhizosphere microbiota changes and the potential for plant growth promotion by applying a free-living, nitrogen-fixing cyanobacterium and the biofilm formulation of cyanobacterium with M. ciceri, relative to M. ciceri applied singly, to two each of desi and kabuli varieties of chickpea.

Materials and methods

Denaturing gradient gel electrophoresis (DGGE) profiles of archaeal, bacterial and cyanobacterial communities and those of phospholipid fatty acids (PLFAs) were obtained to evaluate the changes of the microbial communities in the chickpea rhizosphere. Plant growth attributes, including the pod yields and the availabilities of soil macronutrients and micronutrients, were monitored.

Results and discussion

The DGGE profiles showed distinct and characteristic changes due to the microbial inoculation; varietal differences exerted a marked influence on the archaeal and cyanobacterial communities. However, bacterial communities were modulated more by the type of microbial inoculants. Abundance of Gram-negative bacteria (in terms of notional PLFAs) differed between the desi and the kabuli varieties inoculated with M. ciceri alone, and the principal component analysis of PLFA profiles confirmed the characteristic effect of microbial inoculants tested. Microbial inoculation led to increases in the 100-seed weight and differential effects on the concentrations of available nitrogen and phosphorus, and those of iron, zinc and copper, suggesting their increased cycling in the rhizosphere.

Conclusions

Microbial inoculation of chickpea brought out the characteristic changes in rhizosphere microbiota. Consequently, the growth promotion of chickpea and nutrient cycling in its rhizosphere distinctively differed. Further studies are needed to analyse the association and dynamic changes in the microbial communities to define the subset of microorganisms selected by chickpea in its rhizosphere and the influence of microbial inoculation.

     

<Emphasis Type="Italic">Rhizobium</Emphasis>,<Emphasis Type="Italic"> Bradyrhizobium</Emphasis> and<Emphasis Type="Italic"> Agrobacterium</Emphasis> strains isolated from cultivated legumes

The present study was conducted to isolate and characterize rhizobial strains from root nodules of cultivated legumes, i.e. chickpea, mungbean, pea and siratro. Preliminary characterization of these isolates was done on the basis of plant infectivity test, acetylene reduction assay, C-source utilization, phosphate solubilization, phytohormones and polysaccharide production. The plant infectivity test and acetylene reduction assay showed effective root nodule formation by all the isolates on their respective hosts, except for chickpea isolate Ca-18 that failed to infect its original host. All strains showed homology to a typical Rhizobium strain on the basis of growth pattern, C-source utilization and polysaccharide production. The strain Ca-18 was characterized by its phosphate solubilization and indole acetic acid (IAA) production. The genetic relationship of the six rhizobial strains was carried out by random amplified polymorphic DNA (RAPD) including a reference strain of Bradyrhizobium japonicum TAL-102. Analysis conducted with 60 primers discriminated between the strains of Rhizobium and Bradyrhizobium in two different clusters. One of the primers, OPB-5, yielded a unique RAPD pattern for the six strains and well discriminated the non-nodulating chickpea isolate Ca-18 from all the other nodulating rhizobial strains. Isolate Ca-18 showed the least homology of 15% and 18% with Rhizobium and Bradyrhizobium, respectively, and was probably not a (Brady)rhizobium strain. Partial 16S rRNA gene sequence analysis for MN-S, TAL-102 and Ca-18 strains showed 97% homology between MN-S and TAL-102 strains, supporting the view that they were strains of B. japonicum species. The non-infective isolate Ca-18 was 67% different from the other two strains and probably was an Agrobacterium strain.     

Effects of ectomycorrhizal fungus <Emphasis Type="Italic">Boletus edulis</Emphasis> and mycorrhiza helper <Emphasis Type="Italic">Bacillus cereus</Emphasis> on the growth and nutrient uptake by <Emphasis Type="Italic">Pinus thunbergii</Emphasis>

The present greenhouse study was undertaken to evaluate the effects of co-inoculating the ectomycorrhizal (ECM) fungus Boletus edulis with the mycorrhiza helper bacterium Bacillus cereus HB12 or HB59 on the growth and nutrient uptake of Pinus thunbergii. The inoculation with mycorrhiza helper bacterium significantly (P?≤?0.05) increased the ectomycorrhizal colonization. Treatments with dual inoculum (the mycorrhiza helper bacterium plus mycorrhiza) significantly (P?≤?0.05) increased the P. thunbergii growth. Bacteria–mycorrhizae interactions resulted in a great utilization of phosphate and potassium. The single inoculation resulted in a higher root activity than the control while the co-inoculation led to the highest root activity. The 6-CFDA staining assay showed that B. cereus enhanced fungal activity in ectomycorrhizal symbiosis. The results conclusively suggest that B. cereus isolated from the rhizosphere of P. thunbergii can potentially be used as individual inoculant or co-inoculated with ECM fungi to increase the production in sustainable ecological systems. These results support the potential use of B. cereus (HB12 or HB59) and B. edulis as mixed inoculants stimulating growth of P. thunbergii.     

Influence of heavy metals on the morphology of the soil algae <Emphasis Type="Italic">Xanthonema exile</Emphasis> (Klebs) <Emphasis Type="Italic">Silva</Emphasis>

The effects of copper, nickel, and manganese chlorides on the morphology of the soil algae Xanthonema exile (Klebs) Silva (Xanthophyta) were studied. Copper was applied in concentrations of 1 × 10^?10?10² M/l (1.7 × 10^?5?1.7 mg/l); nickel, in concentrations of 1 × 10^?6?1 M/l (0.237–237 × 10³ mg/l); and manganese, in concentrations of 1 × 10^?4?1 M/l (1.97?197 × 10³ mg/l). The studied metals caused the granulation of cytoplasm, the appearance of barrel-like cells, complete destruction of the cell content, and shortening of vegetative filaments and algal cells. The limits of the tolerance of the algal morphological features (the size of the filaments and cells and the state of the cytoplasm and cell envelope) toward toxicants were determined. They comprised 10^?7 M/l for copper, 10^?3 M/l for nickel, and 10^?1 m/l for manganese. The high sensitivity of these algae to heavy metals allows for their use for biotesting and bioindication purposes, because a change in the morphology or the death of this algal species makes it possible to judge the degree of soil contamination.