摘要:

We compared the ectomycorrhizal community structure of oak forest stands located in either an urban or a rural area. Urban stands had higher N deposition rates, soil heavy metal levels, and earthworm counts than rural stands. Ectomycorrhizal types were quantified on roots of mature oak (Quercus) in soil cores and onQuercus rubraL. seedlings grown in soil cores in the glasshouse. Twenty-six ectomycorrhizal types were distinguished on mature oak in rural soils versus 16 in urban soils. Nine ectomycorrhizal types were distinguished onQ. rubraseedlings grown in rural soils versus seven in urban soils. Despite fewer ectomycorrhizal types in urban soils, richness of ectomycorrhizal types per centimetre fine root of mature oak orQ. rubraseedlings did not differ between urban and rural soils. Ectomycorrhizal colonization (ectomycorrhizal tips/m fine root) was lower in urban than rural soil cores but higher onQ. rubraseedlings grown in urban versus rural soils. Fine root length per unit soil volume was higher in urban than rural stands. No difference in fine root length was observed betweenQ. rubraseedlings grown in urban and rural soils. These differences in ectomycorrhizal community structure between the urban and rural stands are likely due to anthropogenic impacts.Key words: air pollution, anthropogenic impacts, community structure, diversity, ectomycorrhiza,Quercus rubra.

ISSN:0008-4026    

DOI:10.1139/b99-039

出版商:NRC Research Press    

年代:1999

数据来源: NRC

摘要:

Butternut (Juglans cinerea) is seriously threatened by a canker disease caused bySirococcus clavigignenti-juglandacearum, a fungus with no known sexual stage. This pathogen was first reported in 1967 and is now found throughout the native range of butternut, suggesting that it was introduced into North America. We used randomly amplified polymorphic DNA (RAPD) markers to examine genetic variation inS. clavigignenti-juglandacearumover a large portion of the native range of butternut. The 55 RAPD fragments were all found in all 86 isolates of the fungus. This complete monomorphism is consistent with the fungus having been introduced into North America as a single isolate and suggests that if resistant butternut genotypes are found, the pathogen will not likely be able to rapidly evolve genotypes that can attack them.Key words:Sirococcus clavigignenti-juglandacearum,Juglans cinerea, RAPD, randomly amplified polymorphic DNA.

ISSN:0008-4026    

DOI:10.1139/b99-013

出版商:NRC Research Press    

年代:1999

数据来源: NRC

摘要:

Analyses of surface samples of 84 sites from southern Vancouver Island were used to characterize pollen and spore spectra of modern vegetation types. XericQuercus garryanaDougl. and grassland associations can be identified byQuercuspollen and abundant nonarboreal pollen, respectively. Coastal Douglas-fir (Pseudotsuga menziesiivar.menziesii(Mirb.) Franco) forests are distinguished by high proportions ofPseudotsugaand lowPseudotsugatoTsuga heterophylla(Raf.) Sarg. ratios. Coastal Western Hemlock zone forests have abundantTsuga heterophyllapollen. Dry Coastal Western Hemlock subzones have diagnostically abundantPseudotsugaandTsuga heterophyllapollen, and intermediatePseudotsugatoTsuga heterophyllaratios. Moist Coastal Western Hemlock variants are characterised by little or noPseudotsugapollen and highPseudotsugatoTsuga heterophyllaratios. The Mountain Hemlock zone exhibits abundantTsuga mertensiana(Bong.) Carr. pollen percentages and notable nonarboreal pollen and spore values. Relatively highAlnusvalues are not necessarily indicators of dominant alder stands, especially when obtained from open communities.PseudotsugatoTsuga heterophyllaratios are useful as a proxy measure of mean annual precipitation between 700 and 2700 mm.Key words: pollen and spores, surface spectra, Vancouver Island, biogeoclimatic zone, vegetation, precipitation.

ISSN:0008-4026    

DOI:10.1139/b99-038

出版商:NRC Research Press    

年代:1999

数据来源: NRC

摘要:

Previously we showed that a white pine proteinPin mIII (a member of PR10 family of pathogenesis-related proteins) is up-regulated by infection in the white pine blister rust pathosystem. In this study, a blister rust fungal protein,Cro rI, which is similar in size toPin mIII (19 kDa), was detected in the infected white pine tissues. The N-terminal amino acid sequence ofCro rI isolated from infected pine foliage and from fungal mycelia was identical. Rabbit antibody was prepared to a synthetic N-terminal peptide and was purified by immunoaffinity. The purified antibody was used in a Western immunoblot to quantify the amount ofCro rI in various tissues. In western white pine seedlings the amount ofCro rI was significantly (p< 0.0001) higher in infected tissues of cankered seedlings than the infected tissues of resistant seedlings. In sugar pine seedlings, the amount ofCro rI was also significantly (p< 0.01) higher in infected tissues of susceptible seedlings than in resistant seedlings. Furthermore,Cro rI is secreted by the blister rust fungus and was found to be translocated to the healthy tissues of cankered white pines.Cro rI is a major protein that could be extracted from infected foliage by vacuum infiltration. The level ofCro rI detected in the mycelium of different isolates varied. The cDNA ofCro rI was isolated by reverse transcription - polymerase chain reaction. Comparison of the DNA sequence and the deduced protein sequence with data bases revealed that it is a previously undescribed protein. The calculated molecular weight from the deduced protein sequence ofCro rI was 16.7 kDa and the calculated isoelectric point was 9.55. Protein sequence analysis showed thatCro rI has two potential N-linked glycosylation sites in its sequence.Key words: translocation, elicitor, antibody, amino acid sequence.

ISSN:0008-4026    

DOI:10.1139/b99-041

出版商:NRC Research Press    

年代:1999

数据来源: NRC

摘要:

We studied the reproductive biology of two leguminous shrubs endemic of the western Mediterranean regionCytisus striatus(Hill) Rothm. andRetama sphaerocarpa(L.) Boiss. The former is polliniferous, and the latter is nectariferous, with maximum nectar production at the earliest hours of the morning. Germination of the pollen grains in the flowers of the two species occurs only after rupture of the stigmatic surface. It is also necessary in both cases that pollinators (mainlyApis mellifera) visit the flowers for fruit and seed set to occur. A study of the pollen-pistil interaction indicated that there exists prezygotic self-incompatibility in these two species, probably of the gametophytic type, but some self-pollen tubes escape this control and self-fertilize some ovules. However, after hand self-pollination, fruit and seed set is very low for both species. This suggests the existence of a postzygotic rejection mechanism, which could be due either to the existence of late-acting self-incompatibility or to an early action of inbreeding depression, although there are lines of evidence that seem to point to the second possibility. Hand cross-pollination led to an increased number of fruit and seeds per plant relative to the control plants, indicating that reproduction is pollen limited.Key words: late-acting self-incompatibility, prezygotic self-incompatibility, fruit set, seed set, inbreeding depression, Spain.

ISSN:0008-4026    

DOI:10.1139/b99-032

出版商:NRC Research Press    

年代:1999

数据来源: NRC

摘要:

Ten species, six of which were previously placed in the genusFragilaria, were examined, mainly by electron microscopy.Fragilaria germainiiReichardt and Lange-Bertalot is transferred toDiatoma, andFragilaria alpestrisKrasske is transferred toStaurosirella. InFragilaria capucinaDesmazières, one or two rimoportulae are present. InStaurosirella, new details are added concerning the structure of the aerolae; externally, they are multiseriate.Staurosirella pinnata(Ehrenb.) Williams and Round shows an original feature: internal "bridges," perforated by very tiny pores, together join the striae placed on each side of the sternum; moreover, these pores give a particular structure to the striae. InStaurosirella leptostauron(Ehrenb.) Williams and Round, the valvocopula is a closed band with a septum, which is new for this genus. Several species show spinose and nonspinose valves; consequently the presence or the lack of spines does not seem to be an appropriate criterion to distinguish two species

ISSN:0008-4026    

DOI:10.1139/b99-035

出版商:NRC Research Press    

年代:1999

数据来源: NRC

摘要:

Thelocarpella gordensisNav.-Ros. et Cl. Roux gen. et sp. nov., a crustose lichen with endolithic thallus, is only known from the type locality, in Provence (south-east of France), on calcareous sandstone. This species is characterized by entirely immersed perithecioid ascomata, a hamathecium consisting of a typical paraphysoid network, multispored asci (more than 1000 spores in optical section), and colourless small oblong spores. The genusThelocarpelladiffers fromThelocarponby having bitunicate asci with a distinctly thicker wall. Heterogeneity of the genusThelocarponand the systematic position ofThelocarpellaandThelocarponare discussed. The genusTrimmatothelopsisZschacke is considered a synonym ofAcarosporaA. Massal. andThelocarpon robustumEitner identical withAcarospora smaragdulavar.murina(Sandst.) H. Magn.Key words: lichens,Thelocarpella,Thelocarpon, taxonomy.

ISSN:0008-4026    

DOI:10.1139/b99-040

出版商:NRC Research Press    

年代:1999

数据来源: NRC

摘要:

The initial events involved in basidiospore germination and infection of dyer's woad byPuccinia thlaspeoswere studied using scanning electron microscopy and the polymerase chain reaction. The presence of dew was shown to promote infection but was not necessary. Under the conditions of this study, infection of leaf tissue could sometimes be detected using the polymerase chain reaction as quickly as 3 h after inoculation, but 6 h was usually required. Basidiospores and germ tubes were both attached to the leaf surface by an extracellular matrix, and the germ tubes produced appressoria before penetration into the leaf tissue. Penetration was direct rather than through the stomates, and colonization occurred via the growth of intercellular hyphae and haustoria.Key words: biological control, mycoherbicide, noxious weed,Puccinia, dyer's woad.

ISSN:0008-4026    

DOI:10.1139/b99-042

出版商:NRC Research Press    

年代:1999

数据来源: NRC

摘要:

The antibiotic As1A, strongly inhibitory toPhytophthora capsiciLeonian in vitro and in vivo, was isolated from the broth culture ofStreptomyces libaniBaldacci & Grein using various chromatographic procedures. The molecular formula of the antibiotic As1A was deduced to be C45H74O11(M+H, m/z 791.5307) by high resolution fast atom bombardment - mass spectroscopy. The analysis of1H-NMR (nuclear magnetic resonance) and13C-NMR spectroscopy, DEPT experiment, and two-dimensional NMR spectral data revealed that the antibiotic is a macrolide antibiotic having a 26-membered alpha, beta-unsaturated macrolactone ring with a conjugated diene fused to a bicyclic spiroketal. Based on the comparison of NMR data and other chemical properties, the antibiotic As1A turned out to have the same structure as oligomycin A. The antibiotic As1A showed a high level of inhibitory activity againstBotrytis cinereaPers.: Pers.,Cladosporium cucumerinumEllis & Arthur,Colletotrichum lagenarium(C.P. Robin) Berkhout,Magnaporthe grisea(Herb.) Barr, andP. capsici, ranging from 3 to 5 µg·mL-1of MICs. However, no antimicrobial activity was found against yeasts and bacteria. In further evaluation under greenhouse conditions, developments of the Phytophthora disease, anthracnose, and leaf blast were markedly inhibited on pepper (Capsicum annuumL. cv. Hanbyul), cucumber (Cucumis sativusL. cv. Baekrokdadaki), and rice (Oryza sativaL. cv. Nakdong) plants by treatments with the antibiotic As1A, respectively. Control efficacies of the antibiotic As1A against these plant diseases were in general similar to those of metalaxyl, chlorothalonil, and tricyclazole. The antibiotic As1A did not show any phytotoxicity on pepper, cucumber, and rice plants even at 500 µg·mL-1.Key words:Streptomyces libani, oligomycin A, antifungal activity, plant disease control.

ISSN:0008-4026    

DOI:10.1139/b99-044

出版商:NRC Research Press    

年代:1999

数据来源: NRC

摘要:

The understanding of recent changes of the spatial distribution of tree species occurring in agricultural landscapes is essential to realistically predict future positions of the range limit of tree species. In Quebec (Canada), it has recently been suggested that gray birch (Betula populifoliaMarsh.) is spreading rapidly eastward. We tested the hypothesis that this tree migration is strongly facilitated by human activities. Herbarium specimens, historical landscape reconstructions, botanical surveys in mined peatlands and old fields, and dendrochronological data were used to reconstruct past and recent distribution limits of gray birch in the study area (Bas-Saint-Laurent region). Gray birch has been present in the Bas-Saint-Laurent region since at least 1945. However, herbarium specimens and botanical surveys indicate that gray birch individuals were scarce before 1970. The introduction of gray birch in the Bas-Saint-Laurent region seems to be associated with peat mining activities. All mined peatlands located between Rivière-Ouelle and Isle-Verte were colonized by gray birch, but only 11% of old fields surveyed contained at least one gray birch individual. This suggests that the spread of an early successional tree species in an agricultural landscape is facilitated more by the presence of a few large patches favorable to the growth of the species (mined peatlands) than by numerous small patches (old fields). The recent expansion of gray birch populations in the Bas-Saint-Laurent region could be a major concern for peat mining companies because massive invasions of gray birch in abandoned mined bogs may impede successful restoration of these ecosystems.Key words:Betula populifolia, gray birch, Quebec, peatland, old field, landscape ecology

ISSN:0008-4026    

DOI:10.1139/b99-045

出版商:NRC Research Press    

年代:1999

数据来源: NRC