Regulation of dauciform root formation and root phosphatase activities of sedges (<Emphasis Type="Italic">Carex</Emphasis>) by nitrogen and phosphorus

Aims

Dauciform roots (DR) are formed by some Cyperaceae under phosphorus (P) deficiency. To advance our understanding of their physiological function, I ask: Is DR formation regulated by shoot P status or external P supply? How does it respond to nitrogen (N)? Do DR enhance root monoesterase, diesterase or phytase activities and ability to utilize organic P?

Methods

Greenhouse experiments were carried out with two Carex species grown in sand with (1) different combinations of N and P supply, (2) local supply of N or P to root halves, and (3) different organic P forms.

Results

Carex flava produced DR in all treatments. The density of DR and phosphatase activities increased with N supply; they were regulated by shoot P status and external N (but not P) supply. All phosphatase activities increased with DR density. Carex muricata produced no DR and had lower diesterase activity than C. flava but both species grew equally well with diester-P.

Conclusions

DR and phosphatase activities are regulated by both N and P supply. Similar growth responses to nutrients in both species suggest small costs and benefits of DR under experimental conditions but confirmation is needed for plants grown on natural soils.

     

<Emphasis Type="Italic">Sedum</Emphasis> root foraging in layered green roof substrates

Background and aims

Layered profiles of designed soils may provide long-term benefits for green roofs, provided the vegetation can exploit resources in the different layers. We aimed to quantify Sedum root foraging for water and nutrients in designed soils of different texture and layering.

Methods

In a controlled pot experiment we quantified the root foraging ability of the species Sedum album (L.) and S. rupestre (L.) in response to substrate structure (fine, coarse, layered or mixed), vertical fertiliser placement (top or bottom half of pot) and watering (5, 10 or 20 mm week^?1).

Results

Water availability was the main driver of plant growth, followed by substrate structure, while fertiliser placement only had marginal effects on plant growth. Root foraging ability was low to moderate, as also reflected in the low proportion of biomass allocated to roots (5–13%). Increased watering reduced the proportion of root length and root biomass in deeper layers.

Conclusions

Both S. album and S. rupestre had a low ability to exploit water and nutrients by precise root foraging in substrates of different texture and layering. Allocation of biomass to roots was low and showed limited flexibility even under water-deficient conditions.

     

Determining the fate of selenium in wheat biofortification: an isotopically labelled field trial study

Background and aims

Root hair growth and development are important features of plant response to varying soil conditions and of nutrient and water uptake. Most current methods of characterizing root hairs in the field are unreliable or inefficient. We describe a method to quantify root hair area in digital images, such as those collected in situ by minirhizotron systems.

Methods

This method uses ImageJ and R open source software and is partially automated using code presented here. It requires manual tracing of a subset of root hair images (training data set) to which a multivariate logistic regression is fit with each color channel in the image as an independent variable. Thereafter the model is applied to complete sets of selected root hair sections to estimate total root hair area.

Results

There was good agreement between the training data sets and the predictions of the regression models in castor (Ricinus communis L.), maize (Zea mays L.), and papaya (Carica papaya L.).

Conclusion

This method enables time-efficient and consistent quantification of root hairs using in situ root imaging systems that are already widely in use.

     

Iridoid and phenylethanoid/phenylpropanoid metabolite profiles of <Emphasis Type="Italic">Scrophularia</Emphasis> and <Emphasis Type="Italic">Verbascum</Emphasis> species used medicinally in North America

Introduction

Botanicals containing iridoid and phenylethanoid/phenylpropanoid glycosides are used worldwide for the treatment of inflammatory musculoskeletal conditions that are primary causes of human years lived with disability, such as arthritis and lower back pain.

Objectives

We report the analysis of candidate anti-inflammatory metabolites of several endemic Scrophularia species and Verbascum thapsus used medicinally by peoples of North America.

Methods

Leaves, stems, and roots were analyzed by ultra-performance liquid chromatography-mass spectrometry (UPLC-MS) and partial least squares-discriminant analysis (PLS-DA) was performed in MetaboAnalyst 3.0 after processing the datasets in Progenesis QI.

Results

Comparison of the datasets revealed significant and differential accumulation of iridoid and phenylethanoid/phenylpropanoid glycosides in the tissues of the endemic Scrophularia species and Verbascum thapsus.

Conclusions

Our investigation identified several species of pharmacological interest as good sources for harpagoside and other important anti-inflammatory metabolites.

     

Profiling,isolation and structure elucidation of specialized acylsucrose metabolites accumulating in trichomes of <Emphasis Type="Italic">Petunia</Emphasis> species

Introduction

Acylsugar specialized metabolites function as defenses against insect herbivores, and are the most abundant specialized metabolites produced in Solanaceous trichomes. Metabolite profiling provides the foundation for determining the genetic basis of specialized metabolism and its evolution.

Objectives

To profile and identify acylsugar specialized metabolites in three Petunia species: P. axillaris, P. integrifolia and P. exserta.

Methods

Metabolites were profiled using ultra-high performance liquid chromatography/time-of-flight mass spectrometry (UHPLC/TOF MS). Metabolites were purified using solid phase extraction and HPLC, and structures were established using NMR spectroscopy.

Results

Twenty-eight distinct acylsucrose formulas, representing a sampling of more than 100 different detected chemical forms, were purified from three Petunia species and structures have been proposed based on one- and two-dimensional NMR data. 15 of the 28 purified acylsugars were sucrose pentaesters that possess a malonyl group on the fructose ring. These malonate esters can be readily distinguished from other acylsugars based on distinct masses of pseudomolecular ions and fragment ions generated using multiplexed collision-induced dissociation. Chemical diversity of acylsugars was observed between Petunia species, particularly with respect to the lengths of acyl chains and specific acylation positions.

Conclusions

These findings suggest substrate selectivity of various acyltransferases in Petunia species.

     

Bacterial endophytes from rice cut grass (<Emphasis Type="Italic">Leersia oryzoides</Emphasis> L.) increase growth,promote root gravitropic response,stimulate root hair formation,and protect rice seedlings from disease

Background and Aims

Leersia oryzoides, a wild relative of rice (Oryza sativa), may carry potential seed-borne bacterial endophytes which could be used to enhance growth of rice. We hypothesized that seed-associated bacteria from L. oryzoides would be compatible with rice and promote seedling growth, development, and survival.

Methods

We isolated bacteria from seed of L. oryzoides and checked compatibility with rice as well as Bermuda grass seeds for seedling growth promotion. Internal colonisation of bacteria into root cells was observed by ROS staining and microscopic observation. Growth promoting bacteria were evaluated for IAA production, phosphate solubilization and antifungal activities.

Results

Overall, ten bacteria were found to be growth promoting in rice seedlings with effects including restoration of root gravitropic response, increased root and shoot growth, and stimulation of root hair formation. All bacteria were identified by 16S rDNA sequencing. Six bacteria were found to become intracellular in root parenchyma and root hairs in rice and in Bermuda grass seedlings. Six bacteria were able to produce IAA in LB broth with highest (47.06 ± 1.99 μg ml^?1) by LTE3 (Pantoea hericii). Nine isolates solubilized phosphate and inhibited at least one soil borne fungal pathogen.

Conclusions

Seed bacteria of L. oryzoides are compatible with rice. Many of these bacteria become intracellular, induce root gravitropic response, increase root and shoot growth, and stimulate root hair formation in both rice and Bermuda grass seedlings. Presence of bacteria protects seedlings from soil pathogens during seedling establishment. This research suggests that bioprospecting microbes on near relatives of rice and other crop plants may be a viable strategy to obtain microbes to improve cultivation of crops.

     

The bacterial community associated with rose-scented geranium (<Emphasis Type="Italic">Pelargonium graveolens</Emphasis>) leaves responds to anthracnose symptoms

Background

The fungus Colletotrichum is a plant pathogen that causes the anthracnose disease, resulting in huge losses in various crops including the rose-scented geranium (Pelargonium graveolens). Although the bacterial community associated with plants has an important role in the establishment of plant diseases, little is known about what happens in P. graveolens.

Aims

To increase the knowledge about the bacterial community associated with P. graveolens and its relationship with anthracnose disease symptoms.

Methods

Quantitative PCR and high-throughput sequencing were combined to determine the presence of the fungus Colletotrichum and to reveal the bacterial communities associated with different plant parts – root, stem and leaf – and in the rhizosphere and bulk soil, and also to determine the respective bacterial communities associated with P. graveolens leaves symptomatic and asymptomatic for anthracnose disease.

Results

The fungus Colletotrichum was detected in all plant parts and in the surrounding soil. Bacterial communities varied spatially in plants, and the disease symptoms also influenced the composition of the bacterial community. Abundances of operational taxonomic units (OTUs) assigned to the phylum Actinobacteria and to the genus Streptococcus were greatly increased in asymptomatic leaves.

Conclusions

The bacterial community associated to geranium leaves responds to anthracnose symptoms.

     

Growth and root dry matter allocation by pasture legumes and a grass with contrasting external critical phosphorus requirements

Background and aims

This work aimed to quantify the critical external requirement for phosphorus (P) (i.e. extractable-P concentration required for 90 % of maximum yield) for a number of temperate legume species and understand differences in dry matter allocation, P distribution and P acquisition efficiency among these species.

Methods

Shoot and root growth of five legume and one grass species was assessed in response to six rates of P mixed into the top 45 mm of soil in a pot experiment. Dactylis glomerata and Trifolium subterraneum were used as benchmark species; they are commonly grown together in mixed temperate pastures and have low and high critical external requirements for P, respectively. Growth was compared with four alternative legume species: Ornithopus compressus, Ornithopus sativus, Biserrula pelecinus and Trifolium hirtum, that have root morphologies better suited to soil exploration and nutrient acquisition than that of Trifolium subterraneum.

Results

Dactylis glomerata, Ornithopus compressus and Ornithopus sativus had maximum yields equal to or greater than Trifolium subterraneum but achieved this at rates of P less than half that of Trifolium subterraneum. Biserrula pelecinus and Trifolium hirtum had critical P requirements between that of Trifolium subterraneum and the Ornithopus species, but also had lower yields. Root dry matter of Dactylis glomerata and the Ornithopus species in the fertilised soil layer was only marginally changed in response to low P supply. In contrast, Trifolium subterraneum, Trifolium hirtum and to a lesser extent Biserrula pelecinus markedly increased root dry matter allocation to this soil layer. Species with lower critical P requirements were able to take up more P per unit root dry mass than those with higher critical P requirements, particularly at lower levels of P addition.

Conclusions

The high P acquisition efficiencies of the Ornithopus species and Dactylis glomerata were likely to have contributed to their low critical external P requirements. It was surmised that differences in root morphology traits underpin the differences in acclimation to low P stress and P acquisition efficiency among the species.

     

Involvement of reactive oxygen species and Ca<Superscript>2+</Superscript> in the differential responses to low-boron in rapeseed genotypes

Background and aims

Invasive weeds may exert negative impact on other plant species and soil processes. The observed negative impact of an invasive weed species may be driven by allelopathy or nutrient availability.

Methodology

Sorghum halepense is one of the worst invasive weeds in crop fields. We quantified the species richness in the S. halepense-invaded communities and communities not yet invaded by the weed. Sorghum soil and no-sorghum soil were analysed for total phenolics, microbial activity, available nitrogen (N) and organic carbon. Manipulative experiments were carried out to understand the interference potential of S. halepense. Soil was amended with root or shoot leachate of S. halepense, and its impact on plant growth and soil properties was studied.

Results

Out of four S. halepense-sites, lower plant species richness was observed in one site compared to uninvaded sites. S. halepense-invaded soil had higher levels of total phenolics and lower levels of available N. Higher inhibition in the root growth of Brassica juncea or Bidens pilosa was observed in root leachate-amended soil than shoot leachate-amended soil. Shoot leachate-amended soil had higher levels of total phenolics and available N than root leachate-amended soils. Significant reduction in the available N was observed in soil amended with root leachate. Significant decline in the total phenolics over a period of time was observed in soil amended with root leachate or shoot leachate of S. halepense. Higher CO₂ release was observed 24 h after amending soil with root leachate or shoot leachate of S. halepense.

Conclusions

Sorghum halepense interference potential in its soil is likely due to lower levels of available N. Greater reduction in root dry weight of assay species in root leachate amended soil compared to shoot leachate amended soil was likely due to lower levels of available N in root leachate-amended soil. Relative interference potential of both root and shoot leachates or extracts should be evaluated in allelopathy bioassays and further experiments should be designed to distinguish the role of allelochemicals and nutrient availability in plant growth inhibition.

     

Molecular Identification of <Emphasis Type="Italic">Malassezia</Emphasis> Species in Patients with <Emphasis Type="Italic">Malassezia</Emphasis> folliculitis in Sfax,Tunisia

Aim

Malassezia folliculitis is caused by the invasion of hair follicles by large numbers of Malassezia cells. Several Malassezia researches still use cultures, morphology and biochemical techniques. The aim of this study was to identify Malassezia species isolated from patients diagnosed with folliculitis, at the Parasitology and Mycology Laboratory of Sfax University Hospital, and to explore the genetic diversity of Malassezia by using PCR-RFLP and PCR-sequencing targeting the rDNA region of the Malassezia genome.

Patients and Methods

Specimens were taken from 27 patients with Malassezia folliculitis. For the molecular identification, PCR amplification of the 26S rDNAD1/D2 region was carried out using the Malup and Maldown primers and three restriction enzymes (BanI, MspI and HeaII) for RFLP analysis. The nucleotide sequences of each isolate were compared to those in the NCBI GenBank by using BLASTIN algorithm.

Results

Three species of Malassezia yeasts were identified among the 31 Malassezia strains isolated: M. globosa (83.9%), M. sympodialis (12. 9%) and M. furfur (3.2%). The sequence analysis of M. globosa showed six genotypes.

Conclusion

There is a high genotypic variability of M. globosa colonizing patients with folliculitis.

     

Determination and optimization of a strong promoter element from <Emphasis Type="Italic">Bacillus amyloliquefaciens</Emphasis> by using a promoter probe vector

Objective

To construct a promoter probe vector, pBE-bgaB, to screen strong promoters from Bacillus amyloliquefaciens.

Results

266 colonies containing active promoter elements from the genomic DNA of B. amyloliquefaciens were identified. Among these, promoter P41 exhibited the strongest β-Gal activity in Escherichia coli and B. amyloliquefaciens. Sequence analysis showed that promoter P41 contained P _ykuN , a ykuN gene encoding flavodoxin. Optimization of the ribosome-binding site from P41 to P₃₈₂ improved β-Gal activity by ~ 200%.

Conclusion

A new strong promoter for protein expression and genetic engineering of Bacillus species.

     

<Emphasis Type="Italic">Enterococcus faecalis</Emphasis> promotes osteoclast differentiation within an osteoblast/osteoclast co-culture system

Objective

To investigate the effects of heat-killed Enterococcus faecalis ATCC 29212 and P25RC clinical strain (derived from an obturated root canal with apical periodontitis) on osteoclast differentiation within an osteoblast/osteoclast co-culture system.

Results

Heat-killed E. faecalis significantly increased the proportion of multinucleated osteoclastic cells (MNCs) within the co-culture system. The IL-6 level was significantly increased upon exposure to heat-killed E. faecalis. Gene expression levels of NFATc1 and cathepsin K were significantly up-regulated compared to the untreated control. EphrinB2 and EphB4 expressions at both the mRNA and protein levels were also significantly upregulated compared to the untreated control.

Conclusions

Heat-killed E. faecalis can induce osteoclast differentiation within the osteoblast/osteoclast co-culture system in vitro, possibly through ephrinB2-EphB4 bidirectional signaling.

     

Study on the Clinical Features and Prognosis of <Emphasis Type="Italic">Penicilliosis marneffei</Emphasis> Without Human Immunodeficiency Virus Infection

Objective

To improve the diagnosis and treatment of Penicilliosis marneffei without human immunodeficiency virus infection.

Methods

Analyze and review the clinical features, diagnosis and treatment of six cases of P. marneffei without human immunodeficiency virus infection at The First Affiliated Hospital of Fujian Medical University.

Results

Two cases were diagnosed in the ENT Department, three cases in the respiratory department and one case in the dermatological department. Penicillium marneffei infection was confirmed by sputum culture, blood culture and tissue biopsy. After definite diagnosis, one refused further treatment, and others showed significant improvement.

Conclusion

Penicilliosis marneffei is insidious onset and easy to be escaped and misdiagnosed. To achieve early diagnosis and appropriate treatment, doubtful cases should be alerted for the diagnoses as P. marneffei.

     

Metabolomics as a tool for understanding the evolution of <Emphasis Type="Italic">Tabebuia sensu lato</Emphasis>

Background

Plant systematic studies have changed substantially in the last years, stimulated by new strategies for phylogenetic studies. In this regard, chemistry data has been a useful tool for understanding plant phylogenetic relationships.

Objective

Our aim was to apply metabolomic approaches, followed by multivariate statistical analysis and dereplication of Tabebuia sensu lato species, and compare our results with classifications based on traditional taxonomy and molecular phylogeny. We also evaluated the application of metabolomics as a chemotaxonomic identification tool, as well as to enlighten plant chemical evolution.

Methods

Metabolomic data was generated through a high-resolution mass spectrometry with electrospray ionization of 27 Tabebuia sensu lato specimens from different populations, consisting of 15 Handroanthus (from four species) and 12 Tabebuia sensu stricto (from three species). Chemometric tools, such as principal component analysis and metabolite heatmaps, were used to scrutinize the metabolic changes among species.

Results

Tabebuia and Handroanthus species presented different secondary metabolite storage capacity. The genus Tabebuia revealed higher levels of glycosylated iridoids esterified with a phenylpropanoid moiety, such as specioside, verminoside, and minecoside, while Handroanthus accumulated iridoids linked to a simple phenol, lignans, and verbascoside derivatives.

Conclusion

These results corroborate splitting the Tabebuia s.l., which was supported by profound changes in secondary metabolism, suggesting metabolomics as an excellent tool for understanding species evolution.

     

Expression on roots and contribution to maize phytostimulation of 1-aminocyclopropane-1-decarboxylate deaminase gene <Emphasis Type="Italic">acdS</Emphasis> in <Emphasis Type="Italic">Pseudomonas fluorescens</Emphasis> F113

Aims

The plant-beneficial bacterium Pseudomonas fluorescens F113 harbours an acdS gene, which enables deamination of 1-aminocyclopropane-1-carboxylate. The impact of abiotic and biotic factors on the expression of this gene was assessed, as well as the plant-beneficial properties of F113 under different soil moistures.

Methods

An acdS-egfp biosensor was constructed in F113, validated in vitro and used to analyse, by microscopy, its expression on roots of Zea mays comparatively to Beta vulgaris. An acdS mutant was constructed and compared with the wild-type to characterize plant-beneficial effects of F113 on maize lines EP1 and FV2, under well-watered and water deficit conditions.

Results

Different patterns of root colonization and acdS expression were observed according to plant genotype. acdS rhizoplane expression was higher on Beta vulgaris, and on maize line FV2 and hybrid PR37Y15 than on maize line EP1 and teosinte. Strain F113 but not its acdS mutant promoted root growth of EP1 under well-watered conditions and germination of FV2 under water deficit conditions.

Conclusions

Maize lines differed in their ability to induce acdS expression and to respond to P. fluorescens F113. The maize line leading to higher acdS expression, FV2, was the one benefiting from inoculation under water deficit.

     

Genetic and environmental influences on root development in cuttings of selected <Emphasis Type="Italic">Salix</Emphasis> and <Emphasis Type="Italic">Populus</Emphasis> clones – a greenhouse experiment

Aims

This study investigated how genetic determination of adventitious root development compared in experimental hybrid and parental Salix and Populus clones, and how soil bulk density influenced root development.

Methods

Cuttings of 11 Salix clones and 10 Populus clones were grown in pots with water, a low bulk density soil and a high bulk density soil for 4 (water) or 10 weeks (soils). Parameters relating to root development were measured.

Results

Root initiation, total root length (RL), and dry mass (DM), as well as root: shoot relationships in Salix clones exceeded that of Populus clones in all media. For Salix clones RL and DM were highest in S. matsudana?×?pentandra and for Populus clones RL and DM were generally higher in hybrid clones having P. trichocarpa parentage. Mean RL and DM for all clones were generally greater in the low bulk density soil than in the high bulk density soil. There were a greater proportion of thinner roots in the low bulk density soil than in the high bulk density soil.

Conclusions

There were significant differences in root initiation, RL, and DM among clones within each genus. Increasing soil bulk density significantly reduced root development in both Salix and Populus clones. Evaluating cutting root development in pot trials could be a useful clone selection tool in willow and poplar breeding.

     

Development of a novel engineered antibody targeting <Emphasis Type="Italic">Neisseria</Emphasis> species

Objectives

A Neissaria bacterial pilus sugar, bacillosamine, was synthesized and, for the first time, used as a probe to screen a single-chain variable fragment (scFv).

Results

Four Neisseria, Neisseria gonorrhoeae, Neisseria meningitidis, Neisseria sicca and Neisseria subflava, and two negative controls, Streptococcus pneumoniae and Escherichia coli, were tested through ELISA, immunostaining and gold nanoparticle immunological assay. All results indicated that the selected scFv is feasible for the specific detection of Neisseria species via the recognition of bacillosamine.

Conclusions

The recombinant scFv could detect Neisseria strains at 10⁶ CFU/ml.

     

Metabolic response of porcine colon explants to in vitro infection by <Emphasis Type="Italic">Brachyspira hyodysenteriae</Emphasis>: a leap into disease pathophysiology

Introduction

Swine dysentery caused by Brachyspira hyodysenteriae is a production limiting disease in pig farming. Currently antimicrobial therapy is the only treatment and control method available.

Objective

The aim of this study was to characterize the metabolic response of porcine colon explants to infection by B. hyodysenteriae.

Methods

Porcine colon explants exposed to B. hyodysenteriae were analyzed for histopathological, metabolic and pro-inflammatory gene expression changes.

Results

Significant epithelial necrosis, increased levels of l-citrulline and IL-1α were observed on explants infected with B. hyodysenteriae.

Conclusions

The spirochete induces necrosis in vitro likely through an inflammatory process mediated by IL-1α and NO.

     

Intra-specific variation of sperm length in the malaria vector <Emphasis Type="Italic">Anopheles gambiae</Emphasis>: males with shorter sperm have higher reproductive success

Background

Intra-specific variation in sperm length influences male reproductive success in several species of insects. In males of the malaria vector Anopheles gambiae, sperm length is highly variable but the significance of this variation is unknown. Understanding what determines the reproductive success of male mosquitoes is critical for controlling malaria, and in particular for replacing natural populations with transgenic, malaria-resistant mosquitoes.

Methods

A laboratory population of A. gambiae males was tested for intra-specific variation in sperm length. A full-sib quantitative genetic design was used to test for a genetic component of sperm length in A. gambiae males and estimate its heritability. This study also tested for a relationship between sperm length and male reproductive success in A. gambiae. Male reproductive success was measured as the proportions of inseminated and ovipositing females.

Results

There was intra-specific variation of sperm length in A. gambiae. There was no significant genetic variation in sperm length and its heritability was low (h² = 0.18) compared to other insects. Sperm length was correlated with male body size (measured as wing length). Males with short sperm had significantly higher reproductive success than males with long sperm and this was independent of body size.

Conclusion

This is the first study to demonstrate intra-specific variation in sperm length in A. gambiae and that males with short sperm have higher reproductive success. That sperm length influences female oviposition is important for any strategy considering the release of transgenic males.