摘要:

A comparative study on the ontogeny of the fusion of floral organs of the normal (cv. Pearson) and a single-gene mutant, "solanifolia" (sf/sf), of tomato (Lycopersicon esculentumMill.) was conducted. In the normal, floral organs were laterally fused, although the degree and the region of fusion varied in each organ type. In the mutant, the various organs either did not fuse or, if they did, were individually recognizable. The sepals and petals of mutant flowers, unlike those of the normal, did not form a calyx cup and a corolla tube, respectively, and this was related to the limited lateral growth of mutant primordia and the absence of growth in the interprimordial region. Also, petal primordia of the mutant were narrower in width at inception. The stamens of normal flowers were fused by interweaving rows of lateral and adaxial hairs on the anthers. The mutant stamens produced lateral and adaxial hairs, yet they were free. The nonfusion of mutant stamens was related to the smaller primordium widths, greater distance between the primordia, and the larger apex diameter at the time of stamen initiation. The gynoecium of normal flowers consisted of a single ovary, style, and stigma formed by the fusion of carpel primordia. In the mutant, the gynoecium consisted of several carpels, laterally adhered to each other, and each had a recognizable style and stigma. The lack of fusion of mutant carpels was attributed to the larger apex diameter of the mutant during carpel initiation.

ISSN:0008-4026    

DOI:10.1139/b87-030

出版商:NRC Research Press    

年代:1987

数据来源: NRC

摘要:

Electrophysiological experiments were performed on internodal cells ofChara buckelliicultured in saline and freshwater media to see whether the membrane potential (Evo) and membrane conductance (Gm) are dominated by passive K+conductance (K state), passive H+conductance (H state), or active proton pumping (P state). Unlike other euryhaline charophytes,C.buckelliicells cultured under saline conditions were not dominated by any one state, showing little dependence on external K+concentration and pH (pH°).Chara buckelliicells cultured in freshwater share some membrane properties with other freshwater charophytes. Freshwater cells appeared to be in the P state between pH° 5 and 7 as expected but never attained the H state usually observed at high pH° (> 10). Freshwater cells also showed a temporary, threefold increase inGmat pH° 5, which could not be explained by an increase in passive Cl−or K+conductance. Evidence consistent with an electrogenic Cl−/2H+symport in freshwater-grownC.buckelliiat pH° 5 and 7 is also presented.

ISSN:0008-4026    

DOI:10.1139/b87-031

出版商:NRC Research Press    

年代:1987

数据来源: NRC

摘要:

Charomyces amphimelasis described as the type species of a new anamorph genus of Hyphomycetes. The species produces verticillate conidiogenous hyphae that become chains of cylindrical brown ameroconidia with black polar bands. Conidium ontogeny is apparently thallic–arthric, and conidia secede rhexolytically.

ISSN:0008-4026    

DOI:10.1139/b87-032

出版商:NRC Research Press    

年代:1987

数据来源: NRC

摘要:

Major polypeptides were observed upon one-dimensional sodium dodecyl sulfate gel electrophoresis of sclerotial extracts of the following psychrophiles:Myriosclerotinia borealis,Coprinus psychromorbidus,Typhula idahoensis, andTyphula incarnata. In general, the number, molecular mass, and relative proportion of these major sclerotial polypeptides varied considerably from species to species. Furthermore, in the case ofM.borealis, the major sclerotial polypeptide did not appear to be an artifact of culturing conditions since a major polypeptide of similar molecular mass was also present in sclerotia ofM.borealiscollected from the field. Generally, the major sclerotial polypeptides were visible in the sclerotial initials but were not apparent in the vegetative hyphae. Thus, these major sclerotial polypeptides appear to be expressed as a function of sclerotial development. Electrophoresis of protein extracts ofT.idahoensisandT.incarnatainitially solubilized either in sodium dodecyl sulfate or urea sample buffer indicated that the type of denaturant initially used had a profound influence on the relative proportions of the major polypeptides and the overall polypeptide profile. Isoelectric focusing of sclerotial extracts indicated that the isoelectric points of the major sclerotial polypeptides ofM.borealisranged from 6.2 to 6.7, whereas the values of the major sclerotial polypeptides of the other three species were basic and ranged from 7.0 to 7.7.

ISSN:0008-4026    

DOI:10.1139/b87-033

出版商:NRC Research Press    

年代:1987

数据来源: NRC

摘要:

Biomass and reproduction ofGeranium maculatumL. were measured in an artificial canopy light gap and under a closed canopy. The effects of emergence date were also compared. Increased light in the canopy gap resulted in increased biomass, rhizome mass, and percent of plants flowering in the second growing season after gap formation. The importance of proximate carbon in reducing fruit abortion was determined experimentally. The rate of fruit abortion increased and the number of days required for leaf expansion decreased when the plants were shaded by neutral screens. The reproductive effort ofG.maculatumis thus primarily controlled by the previous year's carbon gain, while the proportion of flowers that matured to seeds was a function of proximate carbon gain. Shoots ofG.maculatumemerged over a period of approximately 6 weeks in early spring, with canopy closure occurring midway through this interval. Early emergence of plants under the intact canopy permitted exploitation of the increased light levels in the period prior to canopy closure. This led to slightly increased aboveground growth and rhizome storage and a significant increase in the time spent in leaf expansion, though no differences in reproductive output existed between early and later emerging plants. Early emergence was less advantageous for gap plants. The role of gap-phase growth inG.maculatumis in increased genetic recombination and dispersal during this short period when the balance of sexual versus asexual reproduction is altered.

ISSN:0008-4026    

DOI:10.1139/b87-034

出版商:NRC Research Press    

年代:1987

数据来源: NRC

摘要:

Horse-chestnut cambial cells are characterized by the formation of numerous plasmalemma invaginations and the accumulation of membrane whorls in the vacuoles during the transition from activity to rest. This suggests an active membrane trafficking which was investigated with conventional electron microscopy methods combined with selective cytochemical staining. After the cessation of meristematic activity, cell wall thickening is accompanied by increased dictyosome activity. The incorporation of dictyosome vesicles into the plasma membrane produces an increase in plasmalemma surface area in these nongrowing cells. This increase is compensated for by endocytosis accomplished by the formation of saclike plasmalemma invaginations into the peripheral cytoplasm. These invaginations often contain vesicles and tubules. When these invaginations come in contact with a vacuole, they appear to push the tonoplast into the vacuole and form double-membrane protrusions which may eventually separate from the plasmalemma. ER cisternae situated in the intermembrane zone also appear to be transported into the vacuole. Other cisternae may be directly sequestered into the vacuole or take part in the formation of the myelinlike structures which were observed in the cytoplasm. Thus, the vacuoles appear to fill progressively with complex membranous structures of various origins (plasmalemma, tonoplast, ER). It is suggested that their subsequent disappearance during the winter is a consequence of the hydrolytic action of vacuolar contents.

ISSN:0008-4026    

DOI:10.1139/b87-035

出版商:NRC Research Press    

年代:1987

数据来源: NRC

摘要:

The leaf conductance responses of clones ofPopulus trichocarpa,P.deltoides, and hybrids to changing leaf water potential were examined. Unlike the other species,P.trichocarpanot acclimated to water stress showed an inability to control water loss at low leaf water potential. It is suggested that stomata ofP.trichocarpaplants grown under well-watered conditions remain open in spite of a loss of turgor in the leaf. Preconditioning through water stress of developing leaves, however, leads to greater stomatal control in foliage following rewatering. Leaf conductance of stressed and rewateredP.deltoidesand hybrids remained near zero, while the leaf conductance ofP.trichocarpawas partially reduced.

ISSN:0008-4026    

DOI:10.1139/b87-036

出版商:NRC Research Press    

年代:1987

数据来源: NRC

摘要:

The aim of this work was to determine the direct inhibitory effects of60Co γ-rays on plantlets and to control them in a future program of experimental mutagenesis.Gerbera jamesoniiplantlets were irradiated in vitro using two sources of60Co γ-rays. The following variables were tested: dose rate, total dose, irradiation of the growth medium, time interval between the exposure to γ-rays and the subdivision and transfer to fresh medium, and dose fractionation. These variables were evaluated using regeneration rate of new shoots, callus production, and plantlet growth rate (fresh weight). The optimal dose ranged around 50 Gy at a low dose rate (8.4 Gy∙h−1) and 30 Gy at high dose rate (600 Gy∙h−1). These conditions assured minimal development of callus and 50% of the normal multiplication rate. The γ-irradiation may be done during a 1-week interval before or after transfer on fresh medium, without causing any additional effects. Interrupted doses (3 × 10 Gy at 48-h intervals) caused less important inhibitory effects than a single dose (30 Gy), but the intensity of the reaction varied according to clone and the measured parameter. The clone "Duplex" reacted favourably; this type of treatment ensured better callus and plantlet growth and a higher rate of regeneration. In the case of "Mardi Gras," which is less sensitive to fractionated doses, only the weight of the plantlets was significantly less redu

ISSN:0008-4026    

DOI:10.1139/b87-037

出版商:NRC Research Press    

年代:1987

数据来源: NRC

摘要:

Quantitative analysis and simulation modelling ofLarix laricina(Du Roi) K. Koch branches revealed a complex system of architectural patterns and correlations. Numbers of lateral buds and long shoots were positively correlated with parent-shoot length, but the relationships varied among shoot orders and for sylleptic shoots. For order 2 and sylleptic shoots, numbers of lateral long shoots were also correlated with associated terminal-shoot lengths. Sylleptic shoots produced more lateral long shoots than equivalent proleptic shoots. Lateral long-shoot lengths decreased basipetally and were correlated with terminal-shoot lengths. Lengths of order 2 lateral long shoots also varied independently with crown position. Generally, the degree of apical control decreased and the proportion of short shoots increased with positions of less vigour in the crown. Terminal long-shoot lengths varied with parent-shoot length, location, and to some extent parent-axis leader length. Terminal short-shoot production was associated with shorter parent shoots. Shorter order 2 shoots (<60 mm) and most order 3 shoots produced no lateral long shoots. The net result was that branch structural development ceased in less vigorous crown positions. The spatial disposition of shoots, as defined by elevation and divergence angles, varied with position of origin around and along parent shoots. Although variable, elevation angles decreased and divergence angles increased basipetally.

ISSN:0008-4026    

DOI:10.1139/b87-038

出版商:NRC Research Press    

年代:1987

数据来源: NRC

摘要:

Short shoots and the needles that they bear usually persist for about 3 years on stems and branches ofPinus radiataD. Don. As the main axis thickens with secondary growth, short shoots may elongate by four times their original length, during which process xylem elements become embedded in the stem as "needle trances," although the external shoots appear to remain unchanged. This report describes how elongation in both xylem and phloem results from the insertion of new vascular elements derived from marginal cells of radial parenchyma bands. There was no evidence that the apical meristem contributes to this growth. Possible mechanisms for elongation of pith and cortex are also described.

ISSN:0008-4026    

DOI:10.1139/b87-039

出版商:NRC Research Press    

年代:1987

数据来源: NRC