Search

Foliage on spruce trees (Picea rubens Sarg.) growing on dry SO(2) deposition zones (dry SO(2) deposition ranging from 0.5 and 8.5 S kg ha(-1) year(-1)) downwind from a SO(2) emission source was analyzed to assess chronic effects of long-term low-grade SO(2) deposition on net photosynthesis, stomatal conductance, dark respiration, stomatal antechamber wax structures, elemental concentrations in and on foliage (bulk and surficial concentrations), and types of epiphytic fungi that reside in the phylloplane. Elemental distributions on stomatal antechambers, on fungal colonies, and on smooth surfaces between stomates and fungus colonies were determined with a scanning electronic microscope (SEM) by way of X-ray scanning. It was found that net photosynthesis of newly developed spruce foliage (current-year, and 1-year-old) was not significantly affected by the local SO(2) deposition rates. Sulfur dioxide deposition, however, may have contributed to the gradual decrease in net photosynthesis with increasing needle age. Dark respiration rates were significantly higher on foliage taken from high SO(2) deposition zones. Stomatal rod-web structures deteriorated to flakes with increasing needle age and increasing SO(2) deposition. Further inspection of the needle surfaces revealed an increasing abundance of fungal colonies with increasing needle age. Many fungal taxa were isolated and identified. It was found that black yeasts responded positively, and Xylohypha pinicola responded negatively to high rates of SO(2) deposition. Surficial concentrations of elements such as P, S, K, Cl, Ca were about 10 times higher on fungal colonies than on smooth needle surfaces. Surficial Ca contents on 4 or 5-year-old needles decreased with increasing SO(2) deposition, but surficial S concentrations remained the same. In contrast, bulk foliar Ca and S concentrations increased with increasing SO(2) deposition.

Isolates of the endophytic Leptostroma anamorph of Lophodermium pinastri were collected from needles of Pinus resinosa (red pine) at three locations in Eastern Canada. The DNA of 69 isolates which were morphologically identical was subjected to RFLP analysis using two probes for repeated genomic sequences. One probe, pRWi249, was obtained from a library made from DNA of one of the I. pinastri isolates. The other was an rDNA probe, pTA71, derived from Triticum aestivum . The complementary hybridization patterns of Eco R I-digested DNA obtained using these two probes demonstrated considerable genetic diversity in and between the natural populations of I. pinastri . In total, 27 distinct genotypes were identified of which only three were represented at all three collection sites. No more than 5 isolates of the same genotype were found at any one location and different genotypes were often found among isolates of the same tree. It is concluded that the probes pRWi249 and pTA71 are practical tools for screening isolates of L. pinastri and are likely to be useful for the identification and classification of these endophytes.

The bioactive constituents of extracts of three strains of balsam fir endophytic fungi, reported to cause reduced growth rate and mortality of spruce budworm larvae, have been isolated and characterized. Bioassay-directed fractionation has resulted in the identification of heptelidic acid, 1,5a,6,7,8,9a-hexahydro-6-(1-methylethyl)-1-oxo-spiro[2-benzoxepin-9(3H),2′oxirane]-4-carboxylic acid ( 1 ), and two new analogues, heptelidic acid chlorohydrin ( 2 ), and hydroheptelidic acid ( 3 ), as the biologically active components of ? Phyllosticta sp. strain 76. The active component of Hormonema dematioides strains 53 and 143 was identified as (+)rugulosin ( 4 ), an anthraquinone previously reported to exhibit a wide spectrum of biological activity. This is the first report of the identification of toxins from fungal endophytes of woody plants.

Examination of driftwood, intertidal wood, and submerged panels from the New Brunswick coast of the Bay of Fundy yielded 34 species of marine fungi. With four exceptions, all are first reports for New Brunswick. Five are first reports for the Bay of Fundy and a further four species are first reports for Eastern Canada. Differences were observed between the species found by the various methods.

Endophytic fungi were isolated from the interiors of surface-sterilized needles of balsam fir (Abies balsamea) and red spruce (Picea rubens) in New Brunswick, Canada. Four different fungi were isolated frequently. One species, designated X-W, was isolated exlusively from the petiole segment of red spruce needles. There was no difference in the variety of species isolated from fir needles from two sites, but a difference in frequency of species did exist. Micrographs of the interior of balsam fir needles showed hyphae occupying intercellular spaces and adhering to the outer walls of parenchyma cells. No penetration of cells by either fungus was observed.

Fungi (ca. 2000 isolates) were isolated from balsam fir needles infested by the spruce budworm (Choristoneurafumiferana Clem.) as well as from uninfested needles. Most of the isolates were well-known colonizers of the conifer needle phylloplane. However, approximately 6% of the isolates obtained from the infested needles were unusual needle phylloplane fungi and some of these were toxigenic and (or) pathogenic. Some isolates (23) associated with the needles, frass, and larvae were cultured; solvent extracts of the freeze-dried material of some of these were cytotoxic to HeLa 229 cells. The isolates showing cytotoxicity were grown and the resulting hyphae were incorporated (1%, w/w) into a spruce budworm diet. Hyphae from several isolates in these diets resulted in slower growth rate and mortality. The results of this study show that the presence of the spruce budworm altered the phylloplane mycoflora and the data suggest that there are toxic effects to spruce budworm that consume phylloplane fungi.

The production of metabolites which are toxic to the spruce budworm by endophytic fungi in balsam fir and red spruce needles was investigated. From a collection of ca 900, 94 strains were selected at random and grown in liquid culture. Five strains produced extractable compounds that resulted in mortality and/or a reduced rate of development in spruce budworm larvae. Three of the strains produced potent toxins. These data could explain unresolved mortalities of the spruce budworm in New Brunswick. Cultured spruce budworm cells proved to be a useful bioassay for the identification of strains producing toxins to larvae.

The use of individual autonomy as characterizing personhood is questioned. Two main elements in autonomy, namely (1) individual human rights and power and (2) independency are analyzed in relation ...