摘要:

The root nodules ofDryas drummondii(common name: mountain avens; Family Rosaceae) possess numerous nodule lobes devoid of nodule roots and thus they exhibit theAlnus-type of nodule morphology. Each nodule lobe possesses a nodule meristem, infected cortical cells, and a central vascular cylinder. The endophyte is prokaryotic and has two forms: septate hyphae, 0.3–0.6 μm in diameter, and nonseptate vesicles, ca. 2 μm in diameter; thus, the endophyte appears to be an actinomycete similar to those of otherFrankia-induced nodules. A polysaccharide capsule surrounds both forms of the endophyte and contains numerous electron-dense inclusions near the hyphae in host cells containing both forms of the endophyte.

ISSN:0008-4026    

DOI:10.1139/b81-300

出版商:NRC Research Press    

年代:1981

数据来源: NRC

摘要:

Plants grown in high relative humidity (RH > 90%) before inoculation supported more sporulation than those kept in drier (RH < 30%) conditions. Sporulation ofPeronospora viciae(Berk.) Casp. onPisum sativum(Berk.) Casp. cv. Superb was lower on plants kept under continuous light for 2 weeks before inoculation than on those maintained in a 12 h light: 12 h dark photoperiod. Treatments involving longer photoperiods after inoculation resulted in greater sporulation (intensity) than those where inoculation was followed by an extended dark period. A minimum of 6 h of high humidity (RH > 90%) in the dark was required to initiate sporulation. However, this period was reduced to 3 h if replaced by lower humidity conditions (RH 65%).

ISSN:0008-4026    

DOI:10.1139/b81-301

出版商:NRC Research Press    

年代:1981

数据来源: NRC

摘要:

New information strongly suggests that species of the anamorph-genusDiscosiellaare mycobionts of lichens.Discosiellais revised and four species:D.cylindrospora,D. diospyricomb. nov. (≡Ceuthospora diospyri),D. indicacomb. nov. (≡Shanoria indica), andD. novae-zelandiaesp. nov. are fully described and illustrated.Strigula nitidulais regarded as the teleomorph ofD.indica. An unnamed species ofStrigulais the teleomorph ofD.cylindrospora.

ISSN:0008-4026    

DOI:10.1139/b81-302

出版商:NRC Research Press    

年代:1981

数据来源: NRC

摘要:

Two endophytic clavicipitaceous fungi,Balansia epichloëandB.henningsiana, were isolated from several grasses, cultured on laboratory media, and assessed for their ability to produce the major ergot alkaloids agroclavine, chanoclavine (I), ergonovine, and ergonovinine. Data indicated that the ability of these two species of fungi to biosynthesize ergot alkaloids was host related. All isolates ofB.epichloëfrom smut-grass (Sporobolus poiretii) and 59% of the isolates ofB.henningsianafrom broom-sedge (Andropogon virginicus) produced the major alkaloids in culture. All isolates ofB.epichloëfromEragrostis secundifloraandE.hirsuta, and all isolates ofB.henningsianafromPanicum tenerumfailed to produce alkaloids. The total yield and chemical species of individual alkaloids varied among isolates from a sampling site.

ISSN:0008-4026    

DOI:10.1139/b81-303

出版商:NRC Research Press    

年代:1981

数据来源: NRC

摘要:

Camarops rickiisp. nov. is described from a Brazilian collection. It is noteworthy among describedCamaropsspecies for its comparatively large ascospores. Ultrastructural aspects of the ascospore germ pore are discussed.Camarops peltata, until recently known only from type material collected in Puerto Rico, is discussed and redescribed on material collected in Colombia.

ISSN:0008-4026    

DOI:10.1139/b81-304

出版商:NRC Research Press    

年代:1981

数据来源: NRC

摘要:

Ceratocystis ulmiisolates of known pathogenicity were culturally characterized on a defined synnema production medium (SPM) and American elm wood disks. More aggressive isolates generally produced more synnemata and mycelial pigment on SPM and more synnemata on the wood disks than less aggressive ones. There was no relationship between pathogenicity and radial growth or aerial mycelium production on SPM. Multivariate discriminant analyses on synnema and pigment production and radial growth on SPM and univariate discriminant analyses on synnema production on the wood disks accurately classified the isolates of known pathogenicity into their respective pathogenicity classes. Isolates of unknown pathogenicity also were characterized on SPM and elm wood disks, and pathogenicity predictions made for them using discriminant analyses. Five isolates predicted to be less aggressive were selected for pathogenicity testing, and four were less pathogenic in American elm than a known more aggressive isolate.

ISSN:0008-4026    

DOI:10.1139/b81-305

出版商:NRC Research Press    

年代:1981

数据来源: NRC

摘要:

To determine the role of the apoplast in the loading of the minor veins ofCucurbita pepoL., leaves were examined either for the ability to release selectively the transport sugars, sucrose and stachyose, from the metabolic space (MS) to the free space (FS) or to accumulate selectively exogenously fed transport sugars from the FS into the minor veins. FS extracts collected by vacuum infiltration and centrifugation of specially trimmed leaves were found to contain all sugars also present in ethanol extracts of the MS of the same leaves, but in amounts two orders of magnitude lower. Similarly,14C activity in FS extracts from14CO2-labelled leaves, which was distributed between all sugars, amino acids, and organic acids also found labelled in the MS, was nearly three orders of magnitude lower than in MS ethanol extracts. No excess of the transport sugars was evident in FS extracts. When14C-labelled sucrose, stachyose, or galactose (all 1–2 mM) were infiltrated into the FS a rapid accumulation of these sugars into the mesophyll was apparent, as all sugars were rapidly interconverted into the various sugars normally found labelled in the MS after exposure of leaves to14CO2. However, while leaves exposed to14CO2translocated label predominantly in the form of [14C]stachyose, label in exogenously fed leaves was translocated predominantly as [14C]sucrose, irrespective of the nature of the fed sugar. Exogenously fed transport sugars did not therefore appear to be taken up directly into the minor veins from the FS.The absence of significant levels of transport sugars in the FS as well as the failure ofC.pepoleaves to load any appreciable amount of exogenously supplied [14C]stachyose, the predominant transport sugar in this species, would tend to preclude both a selective release of transport sugars into the apoplast and a selective uptake of transport sugars from the apoplast into the minor veins. A completely symplastic pathway for minor vein loading inC.pepoleaves therefore remains a possibility.

ISSN:0008-4026    

DOI:10.1139/b81-306

出版商:NRC Research Press    

年代:1981

数据来源: NRC

摘要:

Two-year-old seedlings ofPinus strobuswere grown from budbreak to bud set (11 weeks) in air containing 132 ± 26 μg SO2∙m−3. Histological and histochemical effects on elongating needles were examined. Cellular injury was restricted to mesophyll parenchyma. Affected cells manifested a progressive alteration of protoplast staining proportional to the degree of injury. Total carbohydrates and plastids aggregated at cell walls. Total proteins and proteins containing sulfhydryl–disulfide groups decreased. Phospholipid staining in the plasmalemma – cell wall region appeared reduced. Succinic dehydrogenase activity was enhanced and was apparent longer in injured cells. Needle ontogeny was slowed in fumigated seedlings. There were no significant differences in external growth parameters after 11 weeks. The injury can, therefore, be classified as latent or hidden. The SO2effects could contribute to a growth reduction in successive increment

ISSN:0008-4026    

DOI:10.1139/b81-307

出版商:NRC Research Press    

年代:1981

数据来源: NRC

摘要:

Net photosynthesis, transpiration, and stomatal and residual conductances for current-year shoots of Douglas-fir (Pseudotsuga menziesii(Mirb.) Franco) were measured in an open gas exchange system. Terminal shoots of branches and branchlets had larger stomatal and residual conductances, and net photosynthetic and transpiration rates than neighboring lateral shoots under conditions which did not limit gas exchange. The differences between terminal and lateral shoots occurred in both exposed and shaded branches and in trees of different dominance classes. For most of the study, current-year lateral shoots were lighter green than terminal shoots. There were no significant differences in shoot water potential or in the microenvironment between terminal and lateral shoots.Effects of apical control on gas exchange rates were strong in shoots subtending the dominant terminal shoot. These effects were not apparent four whorls from the terminal shoot, in agreement with the hypothesis that apical control can not be exerted at long distances from terminal shoots.

ISSN:0008-4026    

DOI:10.1139/b81-308

出版商:NRC Research Press    

年代:1981

数据来源: NRC

摘要:

The vasculature of elongating lateral branches ofPopulus deltoidesBartr. ex Marsh. was examined to determine how vascular continuity was attained around the entire branch circumference. In a previous study it was found that a pair of original bud traces (A, A′) gave rise to three pairs of bud traces in sequence (a,a′;b,b′;g, g′) that vascularized the axillary bud; the original bud traces then continued upward in the main stem axis. In this study we demonstrated that the lower, abaxial part of the branch cylinder was vascularized by derivatives of the first pair of bud traces (a,a′), the lateral parts primarily by derivatives of the second pair of bud traces (b,b′), and the upper, adaxial part by derivatives of the third pair of bud traces (g,g′). Thus, the organizational pattern for branch vascularization was established during the earliest stages of axillary-bud initiation. Leaves on all lateral branches were anisophyllous; the condition was related to the position of leaves in the phyllotactic array and to their vascularization. The smallest leaves always occurred on the upper branch side and their central traces were diverted upward in the main stem vascular cylinder. The largest leaves were usually on the lower stem side and their central traces were diverted downward. Some first-formed leaves were falcate, and the lateral traces serving the suppressed sides of their laminae were also found to be diverted upward in the main stem axis. It was suggested that both the small anisophyllous and the falcate leaves might result from a lower nutritional status because of their upward-directed leaf traces.

ISSN:0008-4026    

DOI:10.1139/b81-309

出版商:NRC Research Press    

年代:1981

数据来源: NRC