Endohyphal bacterium enhances production of indole-3-acetic acid by a foliar fungal endophyte.

Numerous plant pathogens, rhizosphere symbionts, and endophytic bacteria and yeasts produce the important phytohormone indole-3-acetic acid (IAA), often with profound effects on host plants. However, to date IAA production has not been documented among foliar endophytes -- the diverse guild of primarily filamentous Ascomycota that live within healthy, above-ground tissues of all plant species studied thus far. Recently bacteria that live within hyphae of endophytes (endohyphal bacteria) have been detected, but their effects have not been studied previously.

NasT-mediated antitermination plays an essential role in the regulation of the assimilatory nitrate reductase operon in Azotobacter vinelandii.

Azotobacter vinelandii is a well-studied model system for nitrogen fixation in bacteria. Regulation of nitrogen fixation in A. vinelandii is independent of NtrB/NtrC, a conserved nitrogen regulatory system in proteobacteria.

Geopyxins A-E, ent-kaurane diterpenoids from endolichenic fungal strains Geopyxis aff. majalis and Geopyxis sp. AZ0066: structure-activity relationships of geopyxins and their analogues.

Four new ent-kaurane diterpenoids, geopyxins A-D (1-4), were isolated from Geopyxis aff. majalis, a fungus occurring in the lichen Pseudevernia intensa, whereas Geopyxis sp. AZ0066 inhabiting the same host afforded two new ent-kaurane diterpenoids, geopyxins E and F (5 and 6), together with 1 and 3.

Smardaesidins A-G, isopimarane and 20-nor-isopimarane diterpenoids from Smardaea sp., a fungal endophyte of the moss Ceratodon purpureus.

Five new isopimarane diterpenes, smardaesidins A-E (1- 5) and two new 20-nor-isopimarane diterpenes, smardaesidins F (6) and G (7), together with sphaeropsidins A (8) and C-F (10-13) were isolated from an endophytic fungal strain, Smardaea sp. AZ0432, occurring in living photosynthetic tissue of the moss Ceratodon purpureus . Of these, smardaesidins B (2) and C (3) were obtained as an inseparable mixture of isomers.

Maximizing chemical diversity of fungal metabolites: biogenetically related Heptaketides of the endolichenic fungus Corynespora sp. (1).

In an attempt to explore the biosynthetic potential of the endolichenic fungus Corynespora sp. BA-10763, its metabolite profiles under several culture conditions were investigated. When cultured in potato dextrose agar, it produced three new heptaketides, 9-O-methylscytalol A (1), 7-desmethylherbarin (2), and 8-hydroxyherbarin (3), together with biogenetically related metabolites scytalol A (4), 8-O-methylfusarubin (5), scorpinone (6), and 8-O-methylbostrycoidin (7), which are new to this organism, and herbarin (8), a metabolite previously encountered in this fungal strain.

Sesquiterpene quinones and related metabolites from Phyllosticta spinarum, a fungal strain endophytic in Platycladus orientalis of the Sonoran Desert.

Five new metabolites, (+)-(5 S,10 S)-4'-hydroxymethylcyclozonarone ( 1), 3-ketotauranin ( 3), 3alpha-hydroxytauranin ( 4), 12-hydroxytauranin ( 5), and phyllospinarone ( 6), together with tauranin ( 2), were isolated from Phyllosticta spinarum, a fungal strain endophytic in Platycladus orientalis. The structures of the new compounds were determined on the basis of their 1D and 2D NMR spectroscopic data and chemical interconversions. All compounds were evaluated for inhibition of cell proliferation in a panel of five cancer cell lines, and only tauranin ( 2) showed activity.

Heptaketides from Corynespora sp. inhabiting the cavern beard lichen, Usnea cavernosa: first report of metabolites of an endolichenic fungus.

Two new heptaketides, corynesporol (1) and 1-hydroxydehydroherbarin (2), along with herbarin (3) were isolated from an endolichenic fungal strain, Corynespora sp. BA-10763, occurring in the cavern beard lichen Usnea cavernosa. The structures of 1-3 were elucidated from their spectroscopic data.

Role of GlnK in NifL-mediated regulation of NifA activity in Azotobacter vinelandii.

In several diazotrophic species of Proteobacteria, P(II) signal transduction proteins have been implicated in the regulation of nitrogen fixation in response to NH(4)(+) by several mechanisms. In Azotobacter vinelandii, expression of nifA, encoding the nif-specific activator, is constitutive, and thus, regulation of NifA activity by the flavoprotein NifL appears to be the primary level of nitrogen control. In vitro and genetic evidence suggests that the nitrogen response involves the P(II)-like GlnK protein and GlnD (uridylyltransferase/uridylyl-removing enzyme), which reversibly uridylylates GlnK in response to nitrogen limitation.