Endophytic bacterial communities are associated with leaf mimicry in the vine Boquila trifoliolata.

The mechanisms behind the unique capacity of the vine Boquila trifoliolata to mimic the leaves of several tree species remain unknown. A hypothesis in the original leaf mimicry report considered that microbial vectors from trees could carry genes or epigenetic factors that would alter the expression of leaf traits in Boquila. Here we evaluated whether leaf endophytic bacterial communities are associated with the mimicry pattern. Using 16S rRNA gene sequencing, we compared the endophytic bacterial communities in three groups of leaves collected in a temperate rainforest: (1) leaves from the model tree Rhaphithamnus spinosus (RS), (2) Boquila leaves mimicking the tree leaves (BR), and (3) Boquila leaves from the same individual vine but not mimicking the tree leaves (BT). We hypothesized that bacterial communities would be more similar in the BR-RS comparison than in the BT-RS comparison. We found significant differences in the endophytic bacterial communities among the three groups, verifying the hypothesis. Whereas non-mimetic Boquila leaves and tree leaves (BT-RS) showed clearly different bacterial communities, mimetic Boquila leaves and tree leaves (BR-RS) showed an overlap concerning their bacterial communities. The role of bacteria in this unique case of leaf mimicry should be studied further.

Target specific post-harvest treatment by gamma radiation for the microbial safety of dried Melissa officinalis and Aloysia citrodora.

This study aimed to assess a specific gamma radiation dose to be applied as a post-harvest process to guarantee the microbial safety of two medicinal plants, Melissa officinalis and Aloysia citrodora. Dried plants treated with gamma radiation indicated that a dose of 5 kGy could be applied as a post-harvest treatment process of M. officinalis and A. citrodora, assuring the microbial safety of dried medicinal plants and lowering the potentiality of deleterious effects on plants' quality attributes. This will enhance the safety and quality of the dried plants to be used as raw materials in industrial applications.

The interaction apparatus of Asteridiella callista (Meliolaceae, Ascomycota).

We document here for the first time ultrastructural details of the cellular interaction of Asteridiella callista and its host Stachytarpheta mutabilis var. violacea from Costa Rica. A. callista attaches to the host with appressoria, invades the epidermal cell wall and forms an apoplastic complex cisternal net, presumably for nutrient uptake from its host. This unique structure, called an interaction apparatus (Ia), consists of cisternae surrounded by a membrane continuous with the fungal cytoplasmic membrane. Subsequently the apoplastic trunk of the Ia extends into the host epidermal cell wall and contacts the host cytoplasmic membrane. Electron-opaque material, probably of fungal origin appears at the host cytoplasmic membrane. Finally these electron-opaque deposits are encased by host material. Functional and systematical aspects of this interaction scenario are discussed.

Impact of weed control on arbuscular mycorrhizal fungi in a tropical agroecosystem: a long-term experiment.

Cover crop species represent an affordable and effective weed control method in agroecosystems; nonetheless, the effect of its use on arbuscular mycorrhizal fungi (AMF) has been scantily studied. The goal of this study was to determine root colonization levels and AMF species richness in the rhizosphere of maize plants and weed species growing under different cover crop and weed control regimes in a long-term experiment. The treatment levels used were (1) cover of Mucuna deeringian (Muc), (2) "mulch" of Leucaena leucocephala (Leu), (3) "mulch" of Lysiloma latisiliquum (Lys), (4) herbicide (Her), (5) manual weeding (CD), (6) no weeding (SD), and (7) no maize and no weeding (B). A total of 18 species of AMF belonging to eight genera (Acaulospora, Ambispora, Claroideoglomus, Funneliformis, Glomus, Rhizophagus, Sclerocystis, and Scutellospora) were identified from trap cultures. Muc and Lys treatments had a positive impact on AMF species richness (11 and seven species, respectively), while Leu and B treatments on the other hand gave the lowest richness values (six species each). AMF colonization levels in roots of maize and weeds differed significantly between treatment levels. Overall, the use of cover crop species had a positive impact on AMF species richness as well as on the percentage of root colonized by AMF. These findings have important implications for the management of traditional agroecosystems and show that the use of cover crop species for weed control can result in a more diverse AMF community which should potentially increase crop production in the long run.

Characterization of cytotoxic compound from mangrove derived fungi Irpex hydnoides VB4.

OBJECTIVE: To investigate the cytotoxic activity of endophytic fungi isolated from mangrove fungi. METHODS: In the present study the DNA was isolated and the ITS region of 5.8s rRNA was amplified using specific primers ITS 1 and ITS4 and sequence was determined using automated sequencers. Blast search sequence similarity was found against the existing non redundant nucleotide sequence database thus, identified as Aspergilus flavus, Hyporcaea lixii, Aspergillus niger, Eutorium amstelodami, Irpex hydnoides and Neurospora crassa. Among the seven isolates, one fungi Irpex hydnoides was selected for further studies. The fungi were grown in sabouraud broth for five days and filtrate were separated and subjected to ethyl acetate for further studies. RESULTS: Nearly half (49.25%) of the extracts showed activity (IC50 of 125µg/mL). These values were within the cutoff point of the National Cancer Institute criteria for cytotoxicity (IC50<20 µg/mL) in the screening of crude plant extracts. The GC MS analysis revealed that the active principals might be Tetradecane (6.26%) with the RT 8.606. CONCLUSIONS: It is clear from the present study that mangrove fungi with bioactive metabolites can be expected to provide high quality biological material for high throughout biochemical, anti cancer screening programmes. The results help us conclude that the potential of using metabolic engineering and post genomic approaches to isolate more novel bioactive compounds and to make their possible commercial application is not far off.

New species and nomenclature in Prospodium (Uropyxidaceae, Pucciniales) and the new anamorphic genus Canasta in the neotropics.

Ten new teleomorphic species, two status novus taxa and two new combinations in the genus Prospodium are established. The following anamorphs, all closely related to the genus Prospodium, also are proposed: the genus Canasta, its two new species and a new combination, three new combinations for the genus Uredo.

Naphthoquinone spiroketal with allelochemical activity from the newly discovered endophytic fungus Edenia gomezpompae.

Chemical investigation of the mycelium of Edenia gomezpompae, a newly discovered endophytic fungus isolated from the leaves of Callicarpa acuminata (Verbenaceae) collected from the ecological reserve El Eden, Quintana Roo, Mexico, resulted in the isolation of four naphthoquinone spiroketals, including three new compounds and palmarumycin CP2 (4). We elucidated the structures of the metabolites by extensive NMR spectroscopy studies, including DEPT, COSY, NOESY, HSQC, HMBC, and chiroptical methods. The trivial names proposed for these compounds are preussomerin EG1 (1), preussomerin EG2 (2) and preussomerin EG3 (3). In addition, the X-ray data for 4 were obtained. The bioactivity of the mycelial organic extracts and the pure compounds was tested against three endophytic fungi (Colletotrichum sp., Phomopsis sp., and Guignardia manguifera) isolated from the same plant species (C. acuminata, Verbenaceae) and against four economically important phytopathogenic microorganisms (two fungoid oomycetes, Phythophtora capsici and Phythophtora parasitica, and the fungi Fusarium oxysporum and Alternaria solani). Spiroketals 1-3 displayed significant growth inhibition against all the phytopathogens. IC50 values for the four phytopathogens were from 20 to 170 microg/ml. Palmarumycin CP2 (4) was not bioactive against any of the fungi tested. Compound 1 showed the strongest bioactivity. The acetylated derivatives of preussomerin EG1 (1), 1a and 1b, were obtained and their biological activity was tested on endophytes and phytopathogens. Preussomerin EG1 1, 1a and 1b exhibited significant bioactivity against all microorganisms tested with the exception of Alternaria solani. This is the first report of allelochemicals with antifungal activity from the newly discovered endophytic fungus E. gomezpompae.

Heteroconium and Pirozynskiella n. gen., with comments on conidium transseptation.

Heteroconium citharexyli, the type species of this genus, is illustrated and redescribed as a sooty mold bearing acropetal chains of conidia showing a basifugal sequence of septation. Heteroconium neriifoliae, H. glutinosa and the Heteroconium synanamorph of Antennulariella concinna are congeneric. The latter species is neotypified, illustrated and described. Pirozynskiella new genus, typified by P. solaninum comb. nov. (-Helminthosporium solaninum), differs from Heteroconium in having an obligate association with asterinaceous fungi and in the centrifugal sequence of conidium transseptation after the initial median septum. Pirozynskiella costaricensis comb. nov. (-Dendryphion costaricensis) is illustrated and described. Heteroconium tetracoilum and H. chaetospira are fungicoles of wood and bark; the former has basifugal conidium septation and the latter has a centrifugal sequence. The two latter species can be excluded from the Heteroconium. Basifugal and centrifugal septation of conidia is discussed with reference to several sooty molds, to some foliicolous anamorphs with subcuticular hyphae (Heterosporiopsis) and to some wood and bark hyphomycetes (Septonema, Taeniolella). Ten other species included in Heteroconium are known to me only from their original descriptions; only one (H. asiaticum) is probably a sooty mold.

Additions to the mycobiota of the weed Lantana camara (Verbenaceae) in southeastern Brazil.

A sequel to the work of systematic surveying the mycobiota of Lantana camara, aimed at finding potential biocontrol agents, was carried out during 1995-1996 covering part of its centre of origin in Brazil (state of Minas Gerais). Fifty-eight sampling sites, representing the four main climatic types in the state of Minas Gerais, were surveyed. Additional ad hoc collections were made in the states of Bahia, Espírito Santo, Parana, Rio de Janeiro and São Paulo. Fifteen fungal species were recorded in association with L. camara including the previously undescribed species Phomopsis lantanae-glutinosae sp. nov. Five fungi are also newly recorded on this host in Brazil: Cercospora lantanicola, Corynespora cassiicola, Meliola ambigua, Mycovellosiella lantaniphila and Phornopsis lantanae. The following fungi, previously recorded on L. camara in Brazil, are recorded here for the first time in Minas Gerais: Dendryphielia aspera, Micropustulomyces mucilaginosus, Mycovellosiella lantanae, Pseudocercospora guianensis and Puccinia lantanae.