Nonomuraea ceibae sp. nov., an actinobacterium isolated from Ceiba speciosa rhizosphere.

Strain XMU 110T, isolated from the rhizosphere soil of a flowering tree, Ceiba speciosa, was characterized by polyphasic taxonomy. Phylogenetic analysis based on 16S rRNA gene comparisons revealed that strain XMU 110T showed the highest similarity of 97.9 % to Nonomuraea jabiensis DSM 45507T, and indicated the closest relatives were Nonomuraearoseoviolaceasubsp.roseoviolacea ATCC 27297T (97.8 % 16S rRNA gene sequence similarity) and Nonomuraea salmonea DSM 43678T (97.4 %) after a neighbour-joining analysis. The phenotypic characteristics, as well as the DNA-DNA relatedness values between strain XMU 110T and N. roseoviolaceasubsp. roseoviolacea ATCC 27297T (48.07±1.99 %) and N. salmonea DSM 43678T (40.55±8.30 %), distinguished the novel strain from its closest phylogenetic neighbours. The morphological, physiological and chemotaxonomic characteristics such as phospholipid type, diagnostic diamino acid of the peptidoglycan, whole-cell sugars, major menaquinones and major fatty acids further supported the assignment of strain XMU 110T to the genus Nonomuraea. The G+C content of the genomic DNA was 66.2 mol%. Based on the taxonomic data, strain XMU 110Trepresents a novel species of the genus Nonomuraea, for which the name Nonomuraea ceibae sp. nov. is proposed. The type strain is XMU 110T (=MCCC 1K03213T= KCTC 39826T).

Nonomuraea flavida sp. nov., a novel species of soil actinomycete isolated from Aconitum napellus rhizosphere.

A novel actinomycete strain, YN-5-1T, isolated from the rhizosphere soil of a medicinal plant, Aconitum napellus, was characterized by a polyphasic approach to determine its taxonomic position. The strain showed highest 16S rRNA gene sequence similarities of 97.3, 97.2 and 97.1 % to Nonomuraea turkmeniaca DSM 43926T, Nonomuraea ferruginea DSM 43553T and Nonomuraea candida DSM 45086T, respectively. A wide range of genotypic and phenotypic characteristics, as well as levels of DNA-DNA relatedness between strain YN-5-1T and N. turkmeniaca DSM 43926T (57.46 %), N. ferruginea DSM 43553T (53.50 %) and N. candida DSM 45086T (48.80 %), distinguished the novel isolate from its closest phylogenetic neighbours. The morphological characteristics of strain YN-5-1T were typical of the genus Nonomuraea. Chemotaxonomic characteristics, such as diagnostic diamino acid of the peptidoglycan, whole-cell sugars, phospholipid type, major menaquinone and major fatty acids, further supported the assignment of strain YN-5-1T to the genus Nonomuraea. The G+C content of the genomic DNA was 72.1 mol%. Based on the above data, strain YN-5-1T is considered to represent a novel species of the genus Nonomuraea, for which the name Nonomuraea flavida sp. nov. is proposed. The type strain is YN-5-1T ( = CCTCC AB 2012909T = KCTC 29143T).

Kribbella mirabilis sp. nov., isolated from rhizosphere soil of a herbaceous plant, Mirabilis jalapa L.

Strain XMU 706(T), isolated from the rhizosphere soil of a herbaceous plant, Mirabilis jalapa L., collected from Xiamen City, China, was characterized using a polyphasic approach to clarify its taxonomic position. Strain XMU 706(T) shared the highest 16S rRNA gene sequence similarity with Kribbella antibiotica YIM 31530(T) (97.2%), and formed a distinct branch in the subclade of the genus Kribbella in the 16S rRNA gene phylogenetic tree. The genetic distances of gyrase subunit B gene (gyrB) sequence between strain XMU 706(T) and other species of the genus Kribbella ranged from 0.045 to 0.116, greater than the threshold value of 0.014 for species delineation of this genus. DNA-DNA hybridization experiments gave a DNA-DNA relatedness value of 34.82 ± 6.31% between strain XMU 706(T) and K. antibiotica YIM 31530(T). The chemotaxonomic properties further supported the assignment of strain XMU 706(T) to the genus Kribbella. ll-Diaminopimelic acid was the diagnostic amino acid in the cell-wall peptidoglycan and cell hydrolysates contained ribose and glucose. The major menaquinone was MK-9(H4). The polar lipids comprised diphosphatidylglycerol, phosphatidylglycerol, phosphatidylcholine and other unidentified phospholipids and lipids. The major fatty acids of the strain were anteiso-C15 : 0 and iso-C15 : 0, and the G+C content of the genomic DNA was 67.3 mol%. Based on the results of phylogenetic analysis, phenotypic and genotypic characterization, strain XMU 706(T) represents a novel species of the genus Kribbella, for which the name Kribbella mirabilis sp. nov. is proposed. The type strain is XMU 706(T) ( = KCTC 29676(T) = MCCC 1K00429(T)).

Kibdelosporangium lantanae sp. nov., isolated from the rhizosphere soil of an ornamental plant, Lantana camara L.

Strain XMU 506T, isolated from the rhizosphere soil of an ornamental plant, Lantana camara L., collected from Xiamen City, China, was identified using a polyphasic approach to clarify its taxonomic position. The aerial mycelium of this organism formed long straight or curved chains of spores and sporangium-like structures. The optimum growth occurred at 28-30 °C, pH 7.0 with 0-1% NaCl. Strain XMU 506T showed the highest 16S rRNA gene sequence similarity (96.5%) to Kibdelosporangium philippinense DSM 44226T, and formed a monophyletic clade in the 16S rRNA gene phylogenetic tree together with the type strains of the genus Kibdelosporangium. The chemotaxonomic properties further supported the assignment of strain XMU 506T to the genus Kibdelosporangium: meso-diaminopimelic acid was the diagnostic amino acid in the cell wall peptidoglycan; mycolic acids were not present in the cell wall; the whole-cell hydrolysates contained arabinose, galactose, glucose and ribose. The major menaquinone was MK-9(H4); the phospholipids of the isolate comprised phosphatidylethanolamine, OH-phosphatidylethanolamine, diphosphatidylglycerol and unidentified amino-, glyco- and phospholipids; the major fatty acids of the strain were iso-C16 : 0, C17 : 1 ω6c and iso-C16 : 1 H. The G+C content of genomic DNA was 67.3 mol%. Based on the results of phylogenetic analysis, phenotypic and genotypic characterization, strain XMU 506T represents a novel species in the genus Kibdelosporangium, for which the name Kibdelosporangium lantanae sp. nov. is proposed. The type strain is XMU 506T ( = KCTC 29675T = MCCC 1K00430T).

Deacetyl-mycoepoxydiene, isolated from plant endophytic fungi Phomosis sp. demonstrates anti-microtubule activity in MCF-7 cells.

Deacetyl-mycoepoxydiene (DM), a novel secondary metabolite produced by the plant endophytic fungi Phomosis sp., induced the reorganization of cytoskeleton in actively growing MCF-7 cells by promoting polymerization of tubulin. DM could induce cell cycle arrest at G2/M in MCF-7 cells. Additionally, DM-induced apoptosis was characterized with up-regulating caspase-3, Bax, caspase-9, parp, and p21 while down-regulating Bcl-2 activation. DM conferred dose- and time-dependent inhibitory effects upon cell proliferation of MCF-7 cells both in cultured cells and nude mice with human breast carcinoma xenografts. The results obtained from these in vitro and in vivo models provide new data revealing the potential for DM as a novel microtubule inhibitor.

Phomopsidone A, a novel depsidone metabolite from the mangrove endophytic fungus Phomopsis sp. A123.

One novel pentacyclic depsidone containing an oxetane unit, phomopsidone A (1), together with the reported excelsione (also named as phomopsidone) (2), and four known isobenzofuranones (3-6) were isolated from the mangrove endophytic fungus Phomopsis sp. A123. Their structures were elucidated by 1D and 2D NMR spectroscopic analysis and high resolution mass spectrometry. The bioactivity assays showed that these compounds possess cytotoxic, antioxidant, and antifungal activities.

Mycoepoxydiene inhibits lipopolysaccharide-induced inflammatory responses through the suppression of TRAF6 polyubiquitination [corrected].

Mycoepoxydiene (MED) is a polyketide isolated from a marine fungus associated with mangrove forests. MED has been shown to be able to induce cell cycle arrest and cancer cell apoptosis. However, its effects on inflammatory response are unclear. Herein we showed that MED exhibited inhibitory effect on inflammatory response induced by lipopolysaccharide (LPS). MED significantly inhibited LPS-induced expression of pro-inflammatory mediators such as tumor necrosis factor-α (TNF-α), interleukin (IL)-1ß, IL-6, and nitric oxide (NO) in macrophages. MED inhibited LPS-induced nuclear translocation of nuclear factor (NF)-κB (NF-κB) p65, IκB degradation, IκB kinase (IKK) phosphorylation, and the activation of extracellular signal-regulated kinase (ERK), c-jun N-terminal kinase (JNK), and p38, suggesting that MED blocks the activation of both NF-κB and mitogen-activated protein kinase (MAPK) pathways. Furthermore, the effects of MED on LPS-induced activation of upstream signaling molecules such as transforming growth factor-ß-activated kinase 1 (TAK1), tumor necrosis factor receptor-associated factor 6 (TRAF6) and IL-1 receptor associated kinases1 (IRAK1) were investigated. MED significantly inhibited TAK1 phosphorylation and TRAF6 polyubiquitination, but not IRAK1 phosphorylation and TRAF6 dimerization, indicating that MED inhibits LPS-induced inflammatory responses at least in part through suppression of TRAF6 polyubiquitination. Moreover, MED protected mice from LPS-induced endotoxin shock by reducing serum inflammatory cytokines. These results suggest that MED is a potential lead compound for the development of a novel nonsteroidal anti-inflammatory drug.

A rapid and sensitive LC-MS/MS assay for the quantitation of deacetyl mycoepoxydiene in rat plasma with application to preclinical pharmacokinetics studies.

The purpose of this study was to develop and validate a high-performance liquid chromatographic-tandem mass spectrometric (LC-MS/MS) method for analysis of the deacetyl mycoepoxydiene in rat plasma. The analyte and internal standard (I.S.), benorilate, were extracted from rat plasma by precipitation protein and separated on a C(18) column using acetonitrile-0.5% formic acid as mobile phase. Detection was performed using a turbo-spray ionization source and mass spectrometric positive multi-reaction-monitoring-mode (+MRM) at an ion voltage of +4800 V. The assay was linear over the concentration range 5-5000 ng/mL with the lowest limit of quantification (LLOQ) of 5 ng/mL. The method also afforded satisfactory results in terms of the sensitivity, specificity, precision (intra- and inter-day, RSD<5.8%), accuracy, recovery as well as the stability of the analyte under various conditions. The method was successfully applied to a preclinical pharmacokinetic study in rats after a single intravenous administration of deacetyl mycoepoxydiene 10 mg/kg.

Kribbella amoyensis sp. nov., isolated from rhizosphere soil of a pharmaceutical plant, Typhonium giganteum Engl.

An actinomycete, designated XMU 198(T), was isolated from the rhizosphere soil of a pharmaceutical plant, Typhonium giganteum Engl., collected in Xiamen City, China. 16S rRNA gene sequence analysis showed that the isolate exhibited highest sequence similarities with Kribbella flavida KACC 20148(T), K. karoonensis Q41(T) and K. alba YIM 31975(T) (98.7, 98.4 and 98.2 %, respectively). The chemotaxonomic characteristics further supported the assignment of strain XMU 198(T) to the genus Kribbella: ll-diaminopimelic acid in the cell-wall peptidoglycan; glucose and galactose with minor amounts of ribose as the whole-cell sugars; polar lipids comprising phosphatidylglycerol, diphosphatidylglycerol, phosphatidylcholine, phosphatidylinositol and unidentified phospholipids; a fatty acid profile characterized by the predominance of iso-C(16 : 0), iso-C(14 : 0) and anteiso-C(15 : 0); and MK-9(H(4)) as the main menaquinone. Gyrase subunit B gene (gyrB) sequence analysis showed that the genetic distances between strain XMU 198(T) and all other members of the genus Kribbella were greater than 0.014, the value used as the threshold for species delineation within this genus. A wide range of genotypic and phenotypic characteristics, as well as DNA-DNA relatedness between strain XMU 198(T) and K. flavida DSM 17836(T) (41.18 %), K. karoonensis Q41(T) (38.02 %) and K. alba DSM 15500(T) (50.58 %), distinguished the isolate from its closest phylogenetic neighbours. On the basis of the above data, a novel species of the genus Kribbella, Kribbella amoyensis sp. nov., is proposed. The type strain is XMU 198(T) ( = DSM 24683(T) = NBRC 107914(T)).

Development and in vitro evaluation of deacety mycoepoxydiene nanosuspension.

Deacety mycoepoxydiene (DM), extracted from Phomopsis sp. A123 of thalassiomycetes, is a novel and potent anti-cancer agent. Due to its physicochemical characteristics, the drug, a poorly water-soluble weak acid, shows poor solubility and dissolution characteristics. To improve the solubility and dissolution, formulation of DM as nanosuspension has been performed in this study. Nanosuspensions were developed by high-pressure homogenization (HPH) (DissoCubes(®) Technology) and transformed into dry powder by freeze-drying. The nanosuspension produced was then investigated using optical microscope, photon correlation spectroscopy (PCS), zeta potential measurement, SEM, TEM, AFM, DSC and XRD. To verify the theoretical hypothesis on the benefit of increased surface area, in vitro saturation solubility and dissolution profile were investigated. In addition, the in vitro cell cytotoxicity was examined. Results showed that a narrow size distributed nanosuspension composed of unchanged crystalline state with a mean particle size of 515±18 nm, a polydispersity index of 0.12±0.03 and a zeta potential of -23.1±3.5 mV was obtained. In the in vitro dissolution test an accelerated dissolution velocity and increased saturation solubility could be shown for the MD nanosuspension. The in vitro cytotoxicity experiments provided evidence for an enhanced efficacy of the DM nanosuspension formulation compared to free DM solution. Taken together, these results illustrate the opportunity to formulate DM in nanosuspension form as an anti-prostate cancer delivery system.

Species diversity, distribution, and genetic structure of endophytic and epiphytic Trichoderma associated with banana roots.

Selective isolation, molecular identification and AFLP were used to investigate the distribution of the various species of endophytic and epiphytic Trichoderma associated with banana roots and to compare and contrast their genetic structure. Three specific groups of Trichoderma were observed in the roots of banana. Group one, which made up the largest population, comprised T. asperellum, T. virens, and Hypocrea lixii, which were isolated from both inside and on the surface of the banana roots, while group two, made up of T. atroviride and T. koningiopsis, existed on the surface only. Group three, comprising only T. brevicompactum was isolated from the inside of the roots. The AFLP analysis revealed Nei's diversity indices of 0.15 and 0.26 for epiphytic T. asperellum and T. virens, respectively. The index values of 0.11 and 0.11 were obtained for endophytic T. asperellum and T. virens, respectively. The genetic diversity within endophytic T. asperellum and T. virens was lower than that within the epiphytes. This suggests that endophytic Trichoderma has a higher genetic conservation and is compatible with the relatively stable microenvironments inside roots.

Mycoepoxydiene, a fungal polyketide, induces cell cycle arrest at the G2/M phase and apoptosis in HeLa cells.

Mycoepoxydiene (MED) is a polyketide isolated from a marine fungus associated with mangrove forests. It contains an oxygen-bridged cyclooctadiene core and an α,ß-unsaturated δ-lactone moiety. MED induced the reorganization of cytoskeleton in actively growing HeLa cells by promoting formation of actin stress fiber and inhibiting polymerization of tubulin. MED could induce cell cycle arrest at G2/M in HeLa cells. MED-associated apoptosis was characterized by the formation of fragmented nuclei, PARP cleavage, cytochrome c release, activation of caspase-3, and an increased proportion of sub-G1 cells. Additionally, MED activated MAPK pathways. Interestingly, the time of JNK, p38, and Bcl-2 activation did not correlate with the release of cytochrome c. This study is the first report demonstrating the action mechanism of MED against tumor cell growth. These results provide the potential of MED as a novel low toxic antitumor agent.

Saccharomonospora marina sp. nov., isolated from an ocean sediment of the East China Sea.

A novel, aerobic, Gram-positive actinomycete strain, designated XMU15T, was isolated from an ocean sediment collected from Zhaoan Bay in the East China Sea and was subjected to a polyphasic approach to determine its taxonomic position. The isolate grew optimally at 28 degrees C and at pH 7.0 in the presence of 3% (w/v) NaCl on ISP medium 2. Gelatin liquefaction, milk coagulation and nitrate reduction were positive. Cellulose and starch hydrolysis, hydrogen sulfide and melanin production, and catalase, urease and oxidase activities were negative. The predominant menaquinone of the isolate was MK-9 (H4), and meso-diaminopimelic acid was the diagnostic amino acid in the cell wall. The phospholipids of the isolate comprised diphosphatidylglycerol, phosphatidylglycerol, phosphatidylinositol, and a minor amount of phosphatidylethanolamine. The major fatty acids of the strain were iso-C16:0 (26.36%), C17:1omega6c (16.80%), C15:0 (16.2%), C16:0 (8.90%), C17:1omega8c (7.69%) and iso-C16:1 H (5.95%). The DNA G+C content of the genomic DNA was 68.1 mol%. A phylogenetic tree based on 16S rRNA gene sequences showed that the isolate fell within the evolutionary radiation encompassed by the genus Saccharomonospora and showed the highest 16S rRNA gene sequence similarity (96.7%) to Saccharomonospora xinjiangensis DSM 44391T. Based on the results of 16S rRNA gene sequence analysis and phenotypic and genotypic characterization, strain XMU15T (=KCTC 19701T =CCTCC AA 209048T) represents a novel species of the genus Saccharomonospora, for which the name Saccharomonospora marina sp. nov. is proposed.

Diversities within genotypes, bioactivity and biosynthetic genes of endophytic actinomycetes isolated from three pharmaceutical plants.

One hundred and fifty endophytic actinomycetes were isolated from three pharmaceutical plants, Annonaceae squamosal, Camptotheca acuminate and Taxus chinensis. Bioactivity test showed that 72.4% of the endophytic actinomycetes displayed inhibition against more than one indicator microorganism. In total, 9.3 and 10.7% showed the cytotoxicity and antioxidant activity, respectively. 3-Amino-5-hydroxybenzoic acid synthase (AHBA), ketosynthase (KS), cytochrome P450 hydroxylases (CYPs) and epoxidase (ES) encoding genes were found in 8.8, 23.8, 2.8 and 11.7% isolates, respectively, by genes screening. The identification based on traditional and molecular methods indicated that diverse genotypes of Streptomyces were distributed in the three pharmaceutical plants, and a few strains of Amycolatopsis were also found in the root of T. chinensis. These results indicated that endophytic actinomycetes associated with pharmaceutical plants could be a promising source of drug leads.

Secondary metabolites of Tubercularia sp. TF5, an endophytic fungal strain of Taxus mairei.

One new diterpene glycoside (1) named 16-O-alpha-D-tetraacetylglucopyranosyl hymatoxin C, along with eight known ones including two diterpenoids (2, 3), three cytochalasins (4, 5, 6), dihydroisocoumarin (7) and two C(7)-tetraketides (8, 9), were isolated from the culture of the endophytic fungal strain Tubercularia sp. TF5. The structures of compounds 1-9 were elucidated by spectroscopic methods. The cytotoxic and antimicrobial activities of 1 were analysed but showed no significant activities.

Cytosporone B is an agonist for nuclear orphan receptor Nur77.

Nuclear orphan receptor Nur77 has important roles in many biological processes. However, a physiological ligand for Nur77 has not been identified. Here, we report that the octaketide cytosporone B (Csn-B) is a naturally occurring agonist for Nur77. Csn-B specifically binds to the ligand-binding domain of Nur77 and stimulates Nur77-dependent transactivational activity towards target genes including Nr4a1 (Nur77) itself, which contains multiple consensus response elements allowing positive autoregulation in a Csn-B-dependent manner. Csn-B also elevates blood glucose levels in fasting C57 mice, an effect that is accompanied by induction of multiple genes involved in gluconeogenesis. These biological effects were not observed in Nur77-null (Nr4a1-/-) mice, which indicates that Csn-B regulates gluconeogenesis through Nur77. Moreover, Csn-B induced apoptosis and retarded xenograft tumor growth by inducing Nur77 expression, translocating Nur77 to mitochondria to cause cytochrome c release. Thus, Csn-B may represent a promising therapeutic drug for cancers and hypoglycemia, and it may also be useful as a reagent to increase understanding of Nur77 biological function.

Application of (31P) NMR in analyzing the degradation efficiency of organic phosphorus degrading-bacteria.

HPLC and HPLC-MS are the fastest and most accurate techniques for analysis of organic phosphorus pesticide (OPP) at the present time. Using these techniques, 14 strains of methamidopho (MAP) degrading-bacteria from the area contaminated with MAP have been identified. The results from HPLC and HPLC-MS analyses showed that the highest degradation rate was 73% after 7 days. In order to determine what metabolites will be formed after degradation, a key issue that has been neglected for a long time, we used ((31)P) NMR to track the degradation process. The results showed that different strains produced different metabolites. Ten strains were divided into three groups (groups A, B and C) by their metabolic profiling. Strains in group A degraded MAP into phosphor acid by breaking down all P-N, P-O and P-S bonds in 7 days. Strains in groups B and C had only broken down partially P-N and P-S bonds at the same time. Therefore, the bacterial strains in group A had a greater application potential than the other two groups. In addition, most metal phosphates are unsolvable in water. The analysis of X-ray showed, that the phosphate radicals generated by bacterial degradation induce crystallogenesis of heavy metal salts in water phase and also cause the chemical sedimentation of their crystals. Furthermore, these crystals are hydrogen phosphates. The results suggested that the MAP-degrading bacteria could be used for cleaning up not only the organic phosphorous pesticide contamination but also the phosphorous and heavy metal contamination in water environment simultaneously.

Cytotoxic and antimicrobial metabolites from marine lignicolous fungi, Diaporthe sp.

A new compound (1), named diaporthelactone, together with two known compounds (2 and 3) were isolated from the culture of Diaporthe sp., a marine fungus growing in the submerged rotten leaves of Kandelia candel in the mangrove nature conservation areas of Fugong, Fujian Province of China. The new compound was elucidated to be 1,3-dihydro-4-methoxy-7-methyl-3-oxo-5-isobenzofuran-carboxyaldehyde (1), which showed cytotoxic activity against KB and Raji cell lines (IC50 6.25 and 5.51 microg mL(-1), respectively). Two known compounds, 7-methoxy-4,6-dimethyl-3H-isobenzofuran-1-one (2) and mycoepoxydiene (3), were also demonstrated to exhibit cytotoxic activities for the first time. All three compounds were assessed for antimicrobial activity.

Role of tumor metastasis suppressor gene KAI1 in digestive tract carcinomas and cancer cells.

The KAI1 gene is identified as a tumor metastasis suppressor gene in many types of cancer. We examined KAI1 gene and its protein KAI1/CD82 expression by in situ hybridization and immunohistochemical analysis, and found that KAI1 mRNA and protein expression were inversely correlated with lymph node and distant metastasis in digestive tract carcinomas, but not with age and gender of the patient, or with tumor differentiation. Moreover, KAI1/CD82 protein expression positively reflected the survival outcome of patients. Western blot analysis showed that VP-16 increased KAI1/CD82 protein expression obviously in various cancer cell lines, especially in those that were highly metastatic. This increased KAI1/CD82 expression was associated with its translocation from the cytomembrane to the nucleus, in which it interacted with nuclear p53 protein, forming a strong complex, observed by confocal microscopy and co-immunoprecipitation, respectively. In nude mice, after feeding with VP-16, the number of tumors metastasized from spleen to liver was obviously reduced, and KAI1/CD82 protein expression became stronger in those metastatic tumors. Accordingly, this demonstrated that KAI1 might be used as an indicator for predicting the clinical outcome, and VP-16 may be clinically considered as a promising candidate for anti-metastasis with regard to its potential to upregulate KAI1 expression.

Brefeldin A, a cytotoxin produced by Paecilomyces sp. and Aspergillus clavatus isolated from Taxus mairei and Torreya grandis.

Paecilomyces sp. and Aspergillus clavatus, which were isolated from Taxus mairei and Torreya grandis from southeast China, produced toxic metabolites when grown in liquid culture. Nuclear magnetic resonance techniques, infrared spectrometry, electrospray ionization mass spectroscopy and X-ray analysis identified brefeldin A, a bioactive metabolite produced by a number of fungal species belonging to the genera Alternaria, Ascochyta, Penicillium, Curvularia, Cercospora and Phyllosticta. This is the first report of the isolation of the cytotoxin from Paecilomyces sp. and A. clavatus. The relevance of brefeldin A to the association between these fungi and their host plants is discussed.