摘要:

Pestalopezia tsugaen.sp. is described from cankered branches of western hemlock (Tsuga heterophylla(Raf.) Sarg.) where it is closely associated withSeiridium abietinum(Ell. and Ev.) Sutton.Nipterella tsugaen.sp. is described from dying, understory branches of western hemlock.

ISSN:0008-4026    

DOI:10.1139/b78-186

出版商:NRC Research Press    

年代:1978

数据来源: NRC

摘要:

Polyphenoloxidase and peroxidase were localized and differentiated from each other in the roots and hypocotyls of cotton when these tissues were treated with dihydroxyphenylalanine (DOPA) and diaminobenizidine (DAB), respectively. The DOPA reaction occurred in the thylakoids of plastids from the endodermis of the root and in plastids from several tissues of the hypocotyl. The reaction was inhibited by diethyldithiocarbamate (DIECA), but catalase had no effect. An intense DAB reaction occurred in the epidermal, subepidermal, and endodermal cell walls of both roots and hypocotyls with a lesser reaction in the cortex and stele. DAB also caused a reaction in the microbodies in cells of all tissues, but a reaction could not be detected in other organelles. Aminotriazole (AT) inhibited the reaction in the microbodies but not in the cell walls, whereas the reaction was prevented entirely if H2O2was eliminated from the medium. These results indicate that the two enzyme systems are localized in different and discrete areas in the cotton tissue and that the plastids are intimately involved in phenolic metabolism.

ISSN:0008-4026    

DOI:10.1139/b78-187

出版商:NRC Research Press    

年代:1978

数据来源: NRC

摘要:

Numerous pycnidia ofPlenodomus melilotioccur naturally on roots of legumes and cultures incubated in continuous light. Cultures incubated in darkness produced pycnidia only when various inorganic oxidants and phenolic compounds were incorporated into the culture medium, and even then they produced considerably fewer pycnidia than cultures incubated in continuous light did. The relationship between oxidizing compounds and pycnidia initiation is discussed briefly.

ISSN:0008-4026    

DOI:10.1139/b78-188

出版商:NRC Research Press    

年代:1978

数据来源: NRC

摘要:

Gametophyte morphologies and gametangial sequences in agar cultures ofBommeriaspecies indicated developmental control by an antheridiogen system. The first gametophytes to develop were meristematic and archegonial with ameristic, exclusively antheridial plants appearing later in the same cultures.Bommeriagametophytes were found to form precocious antheridia in response to antheridiogen A but did not respond to antheridiogens B or C. Assays of the nativeBommeriaantheridiogen indicate that it is an A type antheridiogen hormone and that eachBommeriaspecies responds to the hormone produced by its congeners. Differential response byBommeriaspecies to dilute antheridiogen may be useful in concert with morphological characters in establishing relationships among species. Spores which establish colonies of unisexual gametophytes and fail to produce sporophytes in monospore culture suggest the presence of an obligately outcrossing breeding system. Such a breeding system, while maintaining genetic diversity, would restrict range extension of the sexually reproducing species. Only the apogamousBommeria pedatais capable of establishing a new sporophyte plant by a single spore.

ISSN:0008-4026    

DOI:10.1139/b78-189

出版商:NRC Research Press    

年代:1978

数据来源: NRC

摘要:

Four species ofDactylinaare reported for North America, includingDactylina beringicasp.nov. Discussions cover the chemistry, descriptions, maps of distribution, and statements of ecology for each species.

ISSN:0008-4026    

DOI:10.1139/b78-190

出版商:NRC Research Press    

年代:1978

数据来源: NRC

摘要:

Sulphur dioxide emissions from the heavy metal smelter at Trail, British Columbia, reached a peak in the late 1920's. By this date serious destruction of the natural vegetation had occurred. The recommendations of a tribunal set up to investigate the problem of air pollution were implemented in 1941. Hence air qualities suitable for the reestablishment of the vegetation have prevailed for some 30 years. Apart from a decrease in precipitation as one moves south through the study area, environmental conditions appear to be of minor importance in controlling recovery patterns with regrowth being limited principally by a shortage of viable propagules. The degree of destruction of the former vegetation cover is considered to be the major factor underlying the patterns of vegetation recovery. Much of the birch and aspen cover appears to have developed initially from remnant rootstocks, with coniferous regrowth restricted to areas where seed is available from mature trees which survived the fumigations.

ISSN:0008-4026    

DOI:10.1139/b78-191

出版商:NRC Research Press    

年代:1978

数据来源: NRC

摘要:

The pressure chamber technique was evaluated as a method for estimating leaf water potential in cassava (Manihot esculentaCrantz). Xylem pressure potentials (ψP) measured with the pressure chamber were compared with leaf water potential (ψL) obtained for the same leaf with thein situdew-point hygrometer.In both cassava varieties studied, ψLand ψPwere linearly related (r2 = 0.87 and 0.98 for CMC9 and CMC40 respectively). The length of petiole exposed outside the chamber affects the relation between ψLand ψPand should be kept at between 1 and 3 cm for better agreement. In CMC40, ψPwas consistently lower (drier) than ψLby about 1.0 bar (1 bar = 100 kPa) in the entire range of water potential studied, but was not the case in CMC9. The reason for this difference is unclear but may be due to a filling of tissues other than xylem tissues (Boyer 1967) during the measurement of ψPin CMC40. Average xylem osmotic potentials (ψS) were low (−1.0 ± 0.2 bars and −1.0 ± 0.4 bars for CMC9 and CMC40 respectively). It is, therefore, unnecessary to correct for ψSwhen using the pressure chamber to estimate leaf water potentials in cassava.

ISSN:0008-4026    

DOI:10.1139/b78-192

出版商:NRC Research Press    

年代:1978

数据来源: NRC

摘要:

An 8.5-m core from Simpsons Flats, Ferry Co., Washington, includes at least four pollen zones spanning the last 10 000 years. With retreat of the Sanpoil lobe of Pinedale continental ice in the river valley, vegetation with low pollen influx (zone I) and dominated byArtemisia, Gramineae, andPinusbecame prominent. Owing to the narrowness of the valley near Simpsons Flats, it is not clear whether pines were in the valley or on the adjacent upland sites.Mazama ash (ca. 6700 years before present (B.P.)) probably lies disconformably atop zone I and is included within a long-term warmer drier period (zone II) characterized by diploxylon pine pollen. Evidence for an effect of the Mazama ashfall on the vegetation is inconclusive. Zone III (4050–2700 years B.P.) marks a comparatively short period in which climatic conditions were slightly moister (although not necessarily cooler) than today, and the vegetation was dominated by diploxylon pine but with increased influx and frequency ofPicea, Abies, and some haploxylon pine. The modern vegetation in the vicinity of the mire is dominated byPinus ponderosaand Gramineae (includingFestuca idahoensis) and seems to have emerged within the last 2700 years (zone IV).

ISSN:0008-4026    

DOI:10.1139/b78-193

出版商:NRC Research Press    

年代:1978

数据来源: NRC

摘要:

PythiumandPhytophthoracultures were subjected to volatile products from cultures of severalTrichodermaspp., as well as to killed mycelium and extracts therefrom. Oospores were produced byPythium acanthicumandP. arrhenomanesand by one strain of each of the compatible heterothallic pairs ofP. sylvaticumandP. catenulatumtested, only in the presence of a suitable sterol. The volatile products of theTrichodermaspp. tested had no apparent effect on oospore production. Direct contact withTrichodermamycelium, or fat-solvent extracts of such mycelium, resulted in oospore production byP. acanthicum. Such oospore production was likely due to the presence of sterols in theTrichoderma. Similarly, with the compatible pairs ofPhytophthora cinnamomitested, oospores were produced by paired cultures or, in some cases, by the 'A2' strains alone, only in the presence of a suitable sterol, whether or not volatile products fromTrichodermacultures were provided to the growing organisms.

ISSN:0008-4026    

DOI:10.1139/b78-194

出版商:NRC Research Press    

年代:1978

数据来源: NRC

摘要:

The typical patterns of14C-labelled photoassimilatory products of 54 species of Pacific Rhodophyceae (representing 43 genera and six orders) have been compared. Certain heterosides, 2-O-D-glycerol-α-D-galactopyranoside (= floridoside) and 2-D-glycerate-α-D-mannopyranoside (= digeneaside) are the most strongly14C-labelled accumulated low-molecular-weight carbohydrates of the species investigated. The occurrences of [14C]floridoside and [14C]digeneaside are mutually exclusive; while digeneaside has been found in representatives of the Ceramiales only, floridoside is recorded from species of all other rhodophycean orders. The results are discussed with emphasis on the chemotaxonomy of the Rhodophyceae.

ISSN:0008-4026    

DOI:10.1139/b78-195

出版商:NRC Research Press    

年代:1978

数据来源: NRC