Characterization and bioactive potentials of secondary metabolites from Fusarium chlamydosporum.

A search for bioactive secondary metabolites from the endophytic fungus Fusarium chlamydosporum, isolated from the root of Suaeda glauca, led to the isolation of three indole derivatives (1-3), three cyclohexadepsipeptides (4-6), and four pyrones (7-10). The structures of new (1) and known compounds (2-10) were elucidated on the basis of extensive spectroscopic analysis. All these compounds were evaluated for phytotoxic, antimicrobial activities, and brine shrimp lethality. Compound 1 showed significant phytotoxic activity against the radicle growth of Echinochloa crusgalli, even better than the positive control of 2,4-D. Cyclohexadepsipeptides (4-6) and pyrones (7-10) exhibited brine shrimp lethality, especially 4 and 7 with the LD50 values of 2.78 and 7.40 µg mL-1, respectively, better than the positive control.

A teleomorph of the ustilaginalean yeast Moesziomyces antarcticus on barnyardgrass in Japan provides bioresources that degrade biodegradable plastics.

The basidiomycetous yeast Moesziomyces antarcticus (often cited as Pseudozyma antarctica), originally isolated from a sediment sample obtained from Lake Vanda in Antarctica, was asexually typified but closely related to the smut fungus Moesziomyces bullatus (Ustilaginales). We found a smut fungus on an ovary of barnyardgrass (Echinochloa crus-galli) in Japan, which had been identified as M. bullatus. The teliospores germinated and formed yeast-like colonies. Physiological and phylogenetic studies revealed that the characteristics of the yeast-like isolates coincided with those of "P. antarctica." We thus recognised the smut fungus as the teleomorph of M. antarcticus, and then emended the description of M. antarcticus based on the holomorph. The identified fungus could degrade certain biodegradable plastics and produce mannosylerythritol lipids (MELs) in similar qualities as the "P. antarctica" type strain. This discovery provides a significant bioresource, as genetically diverse M. antarcticus isolates could be obtained from the smut fungus.

Bioactive Resorcylic Acid Lactones with Different Ring Systems from Desert Plant Chaetosphaeronema hispidulum. [corrected].

Five new resorcylic acid lactones (RALs) hispidulactones A-E (1, 4, 5, 8, and 9), a new natural product (2), and four known ones (3, 6, 7, and 10) with different ring systems were isolated from the desert plant Chaetosphaeronema hispidulum. [corrected]. The new compounds were characterized by NMR data, CD spectra, and X-ray experiment. The new natural product (2) displayed strongly biological effects on the seedlings growth of Arabidopsis thaliana, Digitaria sanguinalis, and Echinochloa crusgalli with a dose-dependent relationship. Compounds 1, 2, and 6 were also tested cytotoxic activities against three cancer cell lines HCT116, Hela, and MCF7 and only did the new natural product (2) display biological activities with IC50 values at 54.86 ± 1.52, 4. 90 ± 0.02, and 20.04 ± 4.00 µM, respectively, whereas the IC50 values of the positive control cis-platinum were 11.36 ± 0.42, 3.54 ± 0.12, and 14.32 ± 1.01 µM, respectively.

Enterobacter sp. I-3, a bio-herbicide inhibits gibberellins biosynthetic pathway and regulates abscisic acid and amino acids synthesis to control plant growth.

Very few bacterial species were identified as bio-herbicides for weed control. The present research was focused to elucidate the plant growth retardant properties of Enterobacter sp. I-3 during their interaction by determining the changes in endogenous photosynthetic pigments, plant hormones and amino acids. The two bacterial isolates I-4-5 and I-3 were used to select the superior bacterium for controlling weed seeds (Echinochloa crus-galli L. and Portulaca oleracea L.) germination. The post-inoculation of I-3 (Enterobacter sp. I-3) significantly inhibited the weeds seed germination than their controls. The mechanism of bacterium induced plant growth reduction was identified in lettuce treated with I-3 bacterium and compared their effects with known chemical herbicide, trinexapac-ethyl (TE). The treatment of I-3 and TE showed a significant inhibitory effect on shoot length, leaf number, leaf length, leaf width, shoot weight, root weight and chlorophyll content in lettuce seedlings. The endogenous gibberellins (GAs) and abscisic acid (ABA) analysis showed that Enterobacter sp. I-3 treated plants had lower levels of GAs (GA12, GA19, GA20 and GA8) and GAs/ABA ratio and then, the higher level of ABA when compared to their controls. Indeed, the individual amino acids ie., aspartic acid, glutamic acid, glycine, threonine, alanine, serine, leucine, isoleucine and tyrosine were declined in TE and I-3 exposed plants. Our results suggest that the utilization of Enterobacter sp. I-3 inhibits the GAs pathway and amino acids synthesis in weeds to control their growth can be an alternative to chemical herbicides.

Comparison of pathogenicity of Alternaria pellucida and Curvularia lunata on weed Echinochloa species.

Echinochloa spp. are the most important weeds in rice fields. In this research Curvularia lunata and Alternaria pellucida were isolated from these weeds and their pathogenicity effects were compared on these weeds and five rice cultivars in a completely random design with three replications in greenhouse conditions. Fungi were inoculated on weeds and rice cultivars, using spore suspension consisting of 10' spore ml(-1) of distilled water. Results indicated significant effect of Curvularia lunata and Alternaria pellucida on Echinochloa oryzicola and E. crus-galli. In the present study, effect of C. lunata on fresh weight, dry weight and height of Echinochloa species based on variance analysis table, a significant reaction was observed for height and fresh weight, but for dry weight reaction was not significant. The effect of A. pellucida on fresh weight, dry weight and height of Echinochloa species based on variance analysis table, a significant reaction was observed for all the three traits. Also, rice cultivars did not show any significant reaction to C. lunata and A. pellucida. The results showed that in comparison between effect of Curvularia lunata and Alternaria pellucida on Echinochloa spp., disease rating caused by A. pellucida on E. oryzicola and E. crusalli was more than disease rating caused by C. lunata and these species of weed were more susceptible to A. pellucida. However, A. alternata can be considered as a better promising bioherbicide to control Echinochloa spp.

Participation of T regulatory cells in equine recurrent airway obstruction.

Recurrent airway obstruction (RAO) is an equine immune-mediated disease with a high incidence worldwide. The aim of this work was to contribute to the understanding of RAO pathogenesis by studying T cells bearing regulatory markers in peripheral blood (PB) and in bronchoalveolar lavage fluid (BALF) recovered from the same group of susceptible horses before and after exposure to moldy hay, which has been shown to induce RAO signology in our horse herd. With this purpose, mononuclear cells were obtained from the BALF and PB from horses before and after antigenic challenge and were stained with fluorochrome-conjugated antibodies against CD4, CD25 and Foxp3 and subsequently analyzed by flow cytometry. The results indicated that the percentage of CD4+, Foxp3+ cells clearly increased in PB and BALF obtained from horses with RAO. In addition, the percentage of CD4+, CD25(high) cells was greatly augmented in BALF of RAO positive horses compared with a baseline. No changes were observed in the PB compartment. The percentage of CD4+, CD25(high), Foxp3+ cells in BALF increased in horses with active disease compared to horses in remission; this cell population also does not show changes in the PB compartment when RAO positive and RAO negative horses were compared. On the other hand, when the percentage of CD4, Foxp3 positive cells were compared with the percentage of CD4+, CD25(high) cells, the numbers were very similar. This observation was true for PB and BALF cells from non exposed horses as well as horses exposed to antigen. In all the experimental situations studied, the population expressing all of the markers CD4+, CD25(high), Foxp3+ represent only a minor percentage of CD4+, CD25(high) or CD4+, Foxp3 subpopulations; therefore, an significant number of CD4+, CD25(high), Foxp3- and CD4+, CD25(null), Foxp3+ cells must exist. Finally, we conclude that horses with RAO show an airway accumulation of T cells bearing regulatory markers that probably are modulating the course of this disease, and that these T cells may be involved in the resolution of immune-mediated bronchial inflammation.

Comparison of power output by rice (Oryza sativa) and an associated weed (Echinochloa glabrescens) in vascular plant bio-photovoltaic (VP-BPV) systems.

Vascular plant bio-photovoltaics (VP-BPV) is a recently developed technology that uses higher plants to harvest solar energy and the metabolic activity of heterotrophic microorganisms in the plant rhizosphere to generate electrical power. In the present study, electrical output and maximum power output variations were investigated in a novel VP-BPV configuration using the crop plant rice (Oryza sativa L.) or an associated weed, Echinochloa glabrescens (Munro ex Hook. f.). In order to compare directly the physiological performances of these two species in VP-BPV systems, plants were grown in the same soil and glasshouse conditions, while the bio-electrochemical systems were operated in the absence of additional energy inputs (e.g. bias potential, injection of organic substrate and/or bacterial pre-inoculum). Diurnal oscillations were clearly observed in the electrical outputs of VP-BPV systems containing the two species over an 8-day growth period. During this 8-day period, O. sativa generated charge ∼6 times faster than E. glabrescens. This greater electrogenic activity generated a total charge accumulation of 6.75 ± 0.87 Coulombs for O. sativa compared to 1.12 ± 0.16 for E. glabrescens. The average power output observed over a period of about 30 days for O. sativa was significantly higher (0.980 ± 0.059 GJ ha(-1) year(-1)) than for E. glabrescens (0.088 ± 0.008 GJ ha(-1) year(-1)). This work indicates that electrical power can be generated in both VP-BPV systems (O. sativa and E. glabrescens) when bacterial populations are self-forming. Possible reasons for the differences in power outputs between the two plant species are discussed.

Screening and identification of insertion mutants from Bipolaris eleusines by mutagenesis based on restriction enzyme-mediated integration.

Ophiobolin A is sesterterpenoid-type phytotoxin and may be an important candidate for development of new crop protection and pharmaceutical products. The restriction enzyme-mediated integration (REMI) method was used to introduce the plasmid pSH75 into the ophiobolin A-producing filamentous fungus Bipolaris eleusines. A total of 323 stable transformants were obtained, all of which were capable of growing on potato-dextrose agar medium containing 200 µg mL(-1) hygromycin B. The transformation frequency was about 4-5 transformants µg(-1) plasmid DNA. An ophibolin A-deficient transformant (B014) was assessed and the presence of the hph gene in this transformant was confirmed by PCR. The cell-free cultural filtrates of this transformant showed significantly less inhibition on mycelial growth of the fungal pathogen Rhizoctoni solani but little effect on barnyard grass as opposed to that of the wild-type B. eleusines. There was no detectable amount of ophiobolin A in B014 samples measured with HPLC. This research suggests REMI as a potential approach for improving the production of ophiobolin A by B. eleusines via genetic engineering to upregulate certain genes responsible for desired biosynthetic pathways.

Isolation and characterization of a plant growth-promoting rhizobacterium, Serratia sp. SY5.

The role of plant growth-promoting rhizobacteria (PGPR) in the phytoremediation of heavy-metal-contaminated soils is important in overcoming its limitations for field application. A plant growth-promoting rhizobacterium, Serratia sp. SY5, was isolated from the rhizoplane of barnyard grass (Echinochloa crus-galli) grown in petroleum and heavy-metal-contaminated soil. This isolate has shown capacities for indole acetic acid production and siderophores synthesis. Compared with a non-inoculated control, the radicular root growth of Zea mays seedlings inoculated with SY5 can be increased by 27- or 15.4-fold in the presence of 15 mg-Cd/l or 15 mg-Cu/l, respectively. The results from hydroponic cultures showed that inoculation of Serratia sp. SY5 had a favorable influence on the initial shoot growth and biomass of Zea mays under noncontaminated conditions. However, under Cd-contaminated conditions, the inoculation of SY5 significantly increased the root biomass of Zea mays. These results indicate that Serratia sp. SY5 can serve as a promising microbial inoculant for increased plant growth in heavy-metal-contaminated soils to improve the phytoremediation efficiency.

[The purification and characterization of a novel lipid transfer protein from caryopsis of barnyard grass (Echinochloa crusgalli)].

A novel lipid transfer protein called Ec-LTP was isolated from resting caryopsis of weed barnyard grass Echinochloa crusgalli (L.) Beauv.; its molecular weight, amino acid content and N-terminal amino acid sequence were determined. Ec-LTP was a 9150 Da protein, containing eight cysteine residues, which formed four disulfide bonds. The isolated protein could significantly inhibit the development of pathogenic fungi Phytophthora infestans and Helminthosporium sativum, causing the late blight of potato and tomato and the root rot of herbs, respectively.

Degradation of phenanthrene and pyrene in rhizosphere of grasses and legumes.

Phytoremediation is an emerging technology for the remediation of organic soil pollutants such as phenanthrene and pyrene (polycyclic aromatic hydrocarbons, PAHs). The PAH degradation ability of four native Korean plant species (Panicum bisulcatum, Echinogalus crus-galli, Astragalus membranaceus, and Aeschynomene indica) was compared in the greenhouse. During the 80-day experiment, soil samples were collected and analyzed periodically to determine the residual PAH content and microbial activity. More PAHs were dissipated in planted soil (i.e., with a rhizosphere) than in unplanted soil, and there were more obvious effects of plants on pyrene dissipation than on phenanthrene dissipation. After 80 days, >99 and 77-94% of phenanthrene and pyrene, respectively, had been degraded in planted soil, whereas 99% and 69% had been degraded in unplanted soil. This enhanced dissipation of PAHs in planted soils might be derived from increased microbial activity and plant-released enzymes. During the experimental period, a relatively large amount of phenolic compounds, high microbial activity, and high peroxidase activity were detected in planted soils.

[Regulation effects of arbuscular mycorrhizal fungi on the interactions between barnyard grass and upland rice under enhanced nitrogen supply].

A pot experiment was conducted to study the regulation effects of arbuscular mycorrhizal fungi (AMF) on the interactions between Echinochloa crus-galli var. mitis L. and Oryza sativa L. under enhanced N supply (4.0 g N x m(-2) x a(-1)). The results showed that under monoculture condition, the AMF colonization on E. crus-galli increased but that on O. sativa decreased. In the treatments with and without AMF inoculation, upland rice biomass and its P and N uptake increased by 42.35% and 13.48%, 4.07% and 2.55%, and 30.35% and 62.09%, respectively, and barnyard grass biomass and its P and N uptake increased by 20.24% and 15.65%, 3.88% and 4.06%, and 15.10% and 30.35%, respectively. Under mixed cropping, the AMF colonization on E. crus-galli increased but that on O. sativa had little change. In the treatments with and without AMF inoculation, the biomass ratio of O. sativa to E. crus-galli decreased, but N uptake ratio changed a little. The P uptake ratio of O. sativa to E. crus-galli increased in treatment without AMF inoculation but decreased in treatment with AMF inoculation. It was suggested that AMF tended to enhance the competition of E. crus-galli to O. sativa under enhanced N supply.

[Analysis of RAPD fingerprinting in Exserohilum monoceras strains].

Exserohilium monoseras is a potential agent for barnyardgrass (Echinochlao crus-galli) control. This study was to evaluate the genetic diversity of this fungus with 17 strains isolated from different rice growing regions of China by the random amplified polymorphic DNA (RAPD). Among 25 arbitrary primers, 20 primers could get enough amplified bands for all the strains. A total 239 products were amplified. Polymorphic bands were 95.8% of the total products. The 17 strains could be identified based on RAPD fingerprinting established in this study. Genetic distance calculation and cluster analysis resulted in great genetic variation among the strains. The genetic similarity was related with the morphology and the pathogenicity of the strains. The results showed that RAPD maker could be applied in the utilization and the identification of weed pathogen resources.