摘要:

To investigate generation-dependent patterns of variation and differentiation in populations ofAbies amabilisandA. lasiocarpafrom north-coastal British Columbia, seven leaf variables were analyzed by multivariate methods. Principal-components analysis of leaf data from sexually immature trees ofAbies amabilisandA. lasiocarpaindicated no evidence of hybridization between these two species, even on a disturbed site where sexually mature individuals of both species are sympatric. Regression analysis indicated that a change with altitude occurs inA. amabilis. Evidence of population differentiation in immature individuals of both species was demonstrated by canonical variates analysis: (1) inA.amabilisa canyon bottom population appeared distinctive; (2) inA. lasiocarpapopulation differentiation is related to latitude. Variation patterns in both species suggest that geographic distance and taxonomic distance between populations are independent. Such patterns would be predicted if selection were a more important determinant of population differentiation than gene flow. There is some indication that mature populations are more variable than immature.

ISSN:0008-4026    

DOI:10.1139/b81-039

出版商:NRC Research Press    

年代:1981

数据来源: NRC

摘要:

Leaf age at the time of inoculation was a critical factor determining the differential reaction of soybean cultivars to the leaf blight pathogen,Pseudomonas glycinea. Of 23P.glycineastrains from Wisconsin, 22 were of race 4 and one of race 5. Of 14P.glycineastrains obtained from the National Collection of Plant Pathogenic Bacteria, Harpenden, England, one strain was of race 1, nine strains were of race 4, and three strains were of a new physiologic race herein designated as race 9. Pathogenicity to soybean of one strain, NCPPB 1764, could not be confirmed.The reaction of several soybean cultivars to representatives of several physiologic races ofP.glycineadiffered from that originally reported in that a susceptible rather than a resistant response was obtained. This difference may have resulted from experimental conditions that differed slightly from those used by the original investigators.

ISSN:0008-4026    

DOI:10.1139/b81-040

出版商:NRC Research Press    

年代:1981

数据来源: NRC

摘要:

Fusarium moniliformevar.intermediumvar.nov. characterized by the production of both catenate microconidia and polyphialides is described and some nomenclatural problems concerning the Liseola section ofFusariumare discussed.

ISSN:0008-4026    

DOI:10.1139/b81-041

出版商:NRC Research Press    

年代:1981

数据来源: NRC

摘要:

The development of mucilage in the epidermal cells of canola seeds (Brassica campestrisL. cv. Candle) was studied with light and electron microscopy from 5 days after pollination to maturity. During the first 17 days starch was deposited in amyloplasts. At or near the 17th day mucilage appeared between the plasmalemma and the outer tangential wall of the epidermal cells. As the volume of mucilage increased, starch grains disappeared and were totally absent by 25 days. Membrane-bound structures and Golgi bodies were visible within the cytoplasm adjacent to the site of mucilage deposition. At maturity the seed epidermal cells were totally devoid of cytoplasm and engorged with mucilage.

ISSN:0008-4026    

DOI:10.1139/b81-042

出版商:NRC Research Press    

年代:1981

数据来源: NRC

摘要:

The localization of primary action sites of AM-toxin I in host cells was examined by ultrastructural investigation and electron microscopic autoradiography. In susceptible apple leaves, the first effect of the toxin appeared 1 h after treatment in the plasma membranes and chloroplasts of mesophyll and vascular bundle sheath cells and in the plasma membranes of phloem and epidermal cells. Membranes and vesicles which were stained positively with a specific staining solution for grana lamellae were found in the matrix of the chloroplasts, showing that the membranous materials were derived from the disrupted grana. Cell wall lesions were formed around plasmodesmata where plasma membranes were invaginated. The invaginated sites were filled with amorphous materials from degraded cell walls, including membranes derived from plasma membranes and the desmotubules extending from plasmodesmata. The modified chloroplasts and plasma membranes were observed more often as the time after the toxin treatment was prolonged. Modified plastids were not found in the leaf cells. The other cellular membranes appeared normal even 10 h after the treatment. Resistant leaf cells were rarely affected by the toxin. Not all tissues from susceptible apples were sensitive as the toxin caused no necrosis or ultrastructural changes in petal cells. Resistant petal cells were also insensitive to the toxin, but the toxin causes necrosis and ultrastructural changes in moderately resistant petal cells in which the primary effect of the toxin appeared as plasma membrane modifications. Plastids were not affected by the toxin. These results indicate that the action sites of the toxin may be located on the plasma membrane – cell wall association in susceptible leaf cells and in moderately resistant petal cells and also on the chloroplasts of susceptible cells. The results of electron microscopic autoradiography also provided evidence that the action sites of the toxin were present on chloroplasts and the plasma membrane –cell wall association of susceptible leaf cells.

ISSN:0008-4026    

DOI:10.1139/b81-043

出版商:NRC Research Press    

年代:1981

数据来源: NRC

摘要:

Numerical analyses of hop (strobilus) samples showed that the geographical origin of cultivars ofHumulus lupulusL. from North America, Britain, continental Europe, and Japan can be identified with considerable reliability on the basis of morphological examination. Samples of hybrid origin between North American and European plants tended to be similar to American cultivars, but often showed combinations of Old and New World characteristics, making their identification problematical.

ISSN:0008-4026    

DOI:10.1139/b81-044

出版商:NRC Research Press    

年代:1981

数据来源: NRC

摘要:

Only three of nine test fungi formed ectomycorrhizae onAlnus glutinosa,A.incana,A.rhombifolia, andA.sinuatain pure culture syntheses:Alpova diplophloeus,Astraeus pteridis, andPaxillus involutus.Pisolithus tinctoriusformed ectomycorrhizae to a very limited extent onAlnus glutinosa. It is suggested that the entire genusAlnusmay be very specialized regarding its ectomycorrhizal fungus associates, yet, display little infrageneric mycorrhizal specificity.The role of phenolics and possible mechanisms determining ectomycorrhizal specificity are discussed, and the need for research on host–fungus recognition factors is emphasized.

ISSN:0008-4026    

DOI:10.1139/b81-045

出版商:NRC Research Press    

年代:1981

数据来源: NRC

摘要:

A prolonged and intense drought during the summer of 1976 caused soil water potential in the upper 45 cm of the soil profile to decrease below −2.5 MPa. Predawn xylem pressure potential (P) frequently was less than −1.8 MPa. Under conditions of high soil moisture, net photosynthesis averaged more than 8.0 mg CO2∙dm−2∙h−1between 0500 and 1800 hours, and maximum rates of net photosynthesis were above 14.0 mg CO2∙dm−2∙h−1. Average and daily maximum net photosynthesis decreased to less than 1.0 and 8.0 mg CO2∙dm−2∙h−1, respectively, during the peak of the drought. Maximum rates of net photosynthesis observed under controlled light and temperature conditions remained above or near 14.0 mg CO2∙dm−2∙h−1even when predawnPequalled −1.83 MPa. Net photosynthesis seldom decreased below zero if quantum flux densities were greater than the compensation point during this period of record low soil moisture. Environmental conditions, such as fog and clouds, which reduced leaf temperatures and atmospheric evaporative demand, increased net photosynthesis although predawnPwas less than −1.8 MPa. During cloudy days, rates of net photosynthesis were within 80% of those observed under ideal soil moisture conditions. The photosynthetic characteristics of white oak noted during this drought are coupled with other physiological traits of white oak to explain its relative success in the oak–hick

ISSN:0008-4026    

DOI:10.1139/b81-046

出版商:NRC Research Press    

年代:1981

数据来源: NRC

摘要:

Dormant attached or detached shoots of balsam fir were naturally or artificially chilled to induce different states along the rest–quiescence continuum. At the end of the chilling pretreatment, the shoots either were left intact or were debudded and treated with indol-3-ylacetic acid (IAA). The shoots were placed under controlled-environment conditions favorable for growth, and at intervals thereafter, a pulse of [1-14C]IAA was applied to the shoot apex. Measured at the end of the chilling pretreatment, [14C]IAA velocity and flux decreased with increasing duration of chilling (i.e., as rest graded into quiescence). The time required to commence cambial growth and to attain maximum rates of cambial activity and [14C]IAA transport also decreased as rest changed to quiescence. Transport in actively growing shoots exceeded that in quiescent shoots, but was similar to that in resting shoots. The [14C]IAA pulse moved basipetally as unchanged IAA, was blocked by a bark + cambium girdle, and was inhibited by abscisic acid and long-term application of exogenous IAA. The results indicate that: (1) the long-distance, cambium-located, IAA transport system demonstrated in dicotyledonous species also operates in conifers, (2) during the dormant period changes occur in [14C]IAA transport and in the cambial response to exogenous IAA, (3) the change in [14C]IAA transport is the result of change in the transporting capability of cells in the cambial zone, and (4) the change in [14C]IAA transport is not the cause of the differential response of quiescent and resting cambia to exogenous IAA.

ISSN:0008-4026    

DOI:10.1139/b81-047

出版商:NRC Research Press    

年代:1981

数据来源: NRC

摘要:

Net photosynthesis, transpiration, and stomatal conductance of terminal shoots of Douglas-fir (Pseudotsuga menziesii(Mirb.) Franco) were measured using an open gas exchange system. Correlations between these physiological parameters and environmental variables on an overcast day, a cool partly sunny day, and a day of high temperature and leaf–air vapor pressure difference are presented. Diurnal variation in shoot water potential and intercellular space CO2concentration had little effect on the physiological parameters. Leaf–air vapor pressure difference and (or) leaf temperature had considerable influence on days of high temperatures. Net photosynthetic rate was strongly correlated with photon flux density on completely overcast days.Stomatal conductance exerted little control on diurnal variation of net photosynthetic rates on overcast days because stomatal conductance saturated at lower photon flux densities than net photosynthesis. When net photosynthesis was light saturated parallel responses of stomatal and residual conductances to vapor pressure difference and (or) leaf temperature occurred. Intercellular space CO2concentration remained fairly constant when net photosynthesis was light saturated.

ISSN:0008-4026    

DOI:10.1139/b81-048

出版商:NRC Research Press    

年代:1981

数据来源: NRC