摘要:

The effects of the herbicide DPX-4189 (2-chloro-N-((4-methoxy-6-methyl-1,3,5-triazin-2-yl)aminocarbonyl)benzenesulfonamide) on anthocyanin accumulation, phenylalanine ammonia lyase (PAL) activity, and ethylene production in seedlings of soybean (Glycine maxL.) were investigated. Application of 1 μg DPX-4189 per plant led to an increase in anthocyanin content in soybean hypocotyls. The increase in anthocyanin content became evident 4 days after application of the herbicide. Accompanying the increase in anthocyanin content was an eightfold increase in extractable PAL activity. An increase in endogenous ethylene evolution also accompanied the increase in anthocyanin content. Application of silver nitrate (an inhibitor of ethylene action) to herbicide-treated seedlings did not prevent the increase in anthocyanin content. Application of 2-chloroethylphosphonic acid (an ethylene-releasing compound) to soybean seedlings stimulated PAL activity but had no effect on anthocyanin content. These results indicated that ethylene did not play a role in DPX-4189 mediated anthocyanin accumulation.

ISSN:0008-4026    

DOI:10.1139/b82-097

出版商:NRC Research Press    

年代:1982

数据来源: NRC

摘要:

Myrica galeL. populations growing in central Massachusetts were observed throughout the ice-free season. Nitrogenase activity appeared in mid-May shortly after budbreak, was at its maximum between late June and mid-August, and disappeared in late October after all leaves had fallen. Growth of overwintering nodules began in early May and was largely complete by mid-July. Most nodules (88%) lived for 3 years or less and 61% of the nodule biomass present in autumn was produced during the current season.Colonizing hyphae of theFrankiasp. endophyte were seen throughout the year in partially expanded cortical cells near the nodule lobe apex. Vesicles first appeared in mature cortical cells coincident with the onset of nitrogenase activity in mid-May, occupied the bulk of the infected tissue during the summer, and disappeared as nitrogenase activity ceased in late October. Evidence is presented that the vesicles are the site of nitrogenase activity and are newly produced each season in freshly formed nodule lobe tissue. Sporangia frequently formed in mature infected cells in nodules at one site but were rare at another. The processes described here inM. galeare probably typical of winter-deciduous actinorhizal plants.

ISSN:0008-4026    

DOI:10.1139/b82-098

出版商:NRC Research Press    

年代:1982

数据来源: NRC

摘要:

Doses from 0.002 to 2.0 ppm of benzyladenine (BA) increased the water content in 15-day-old plants ofLemna minorL. However, a concentration of 5.0 ppm decreased it. The total esterified fatty acid content increased up to 2.0 ppm and decreased at 5.0 ppm, compared with controls. The BA increased the percentages of total palmitic and α-linolenic acids and decreased the percentage of total linoleic acid, mainly for higher doses. At 2.0 and 5.0 ppm of BA, the proportions of phospholipids increased strongly as compared with galactolipids (especially the diacylgalactosylglycerol) and total neutral lipids. In phosphatidylcholine, phosphatidylethanolamine, and phosphotidylinositol, the α-linolenic acid content exhibited a marked increase at the expense of linoleic acid of these phospholipids. The percentage of α-linolenic acid in diacylgalactosylglycerol remained constant in the presence of BA, but it decreased in diacyldigalactosylglycerol. At concentrations of 2.0 and 5.0 ppm, the α-linolenic acid content of total neutral lipids increased greatly. The modifications observed in the lipid composition ofL. minor, at 2.0 and 5.0 ppm in BA, suggest that the cell membranes (particularly those of chloroplasts) and their functions may be altered by these high doses of cytokinin.

ISSN:0008-4026    

DOI:10.1139/b82-099

出版商:NRC Research Press    

年代:1982

数据来源: NRC

摘要:

Seedlings of English oak (Quercus roburL.) and cork oak (Quercus suberL.) grown in minirhizotrons have (i) semiplagiogeotropic lateral roots which reorient their tip when placed in certain positions; their growth is very brief; (ii) taproots which are strongly orthogeotropic when they are short and weakly orthogeotropic when they are 2 m long; (iii) replacement taproots, appearing after a decapitation of the taproot, which are either orthogeotropic or slightly oblique. The orthogeotropic caracteristics of taproots and replacement taproots seem difficult to alter.Deviating, slowing the growth, blocking, or drying the tip of the taproot induces various transformations of lateral roots. Axial growth, radial growth, growth of the ramifications, and geotropism of the lateral roots can be changed separately, but in a certain order. Growth correlations within the root system of young oaks are compared with those already studied in the root system ofTheobroma cacaoL. The nature of the correlations is discussed.

ISSN:0008-4026    

DOI:10.1139/b82-100

出版商:NRC Research Press    

年代:1982

数据来源: NRC

摘要:

Eleven sites representing the range of alpine and subalpine community types in Deer Park were chosen for an intensive study of high-elevational meadow habitats in the Olympic Mountains, Washington. The vegetation, soils, and important physical features of each site are described.The 11 sites were ordered by reciprocal averaging. The resulting first axis was interpreted as being a moisture–exposure gradient which separates the mesic subalpine meadows from the xeric alpine meadows. This gradient is determined by snowmelt patterns, aspect, and wind. Mesic subalpine sites are sheltered from the wind and direct insolation. Xeric alpine sites have shallow or no snowpacks and receive the full impact of the wind and sun. The second axis is a soil stability gradient that predominately affects the xeric sites. Stable soils are protected from wind erosion, frost heaving, and needle ice by windbreaks and long-lasting snowpacks.

ISSN:0008-4026    

DOI:10.1139/b82-101

出版商:NRC Research Press    

年代:1982

数据来源: NRC

摘要:

Endophytic fungi were isolated from five species of broad-leaved evergreen shrubs from 16 sites in western Oregon. Rates of infection were 76% forMahonia nervosa, 44% forArctostaphylos uva-ursi, 37% forGaultheria shallon, 29% forMahonia aquifolium, and 25% forUmbellularia californica. Incidence of leaf infections by more than one fungal taxon was 20–56%, 72–90% of which had only two infections. Rates of overall infection were higher in samples taken from densely wooded sites than in samples taken from more open sites. A pattern of species dominance is seen where the most common endophyte of a given host is isolated less frequently from other hosts; less commonly isolated endophytes appear to be less host specific. The most commonly isolated endophytes includePhyllosticta pyrolaeonA. uva-ursiandG. shallon, Leptothyrium berberidisonM. nervosa, Septogloeumsp. onM. nervosaandU. californica, andPhomopsissp., predominantly onM. aquifolium, but present on all hosts. Some of the fungi isolated from evergreen shrubs in this study were previously isolated from conifer needles; however, most represent new records.

ISSN:0008-4026    

DOI:10.1139/b82-102

出版商:NRC Research Press    

年代:1982

数据来源: NRC

摘要:

Microsporogenesis was studied inLarix laricinain eastern Newfoundland at weekly intervals from October to April in four successive seasons. Male strobili were fixed in a 3:1 ethanol – propionic acid mixture, stained in alcoholic carmine, and squashed in 45% acetic acid.Pollen mother cells began development from interphase in early October and passed through leptotene, zygotene, and pachytene by mid-November. They remained in diplotene until mid-March to early April when meiosis was completed over a 2-to 4-week period. Microspores were produced by early May. The pattern of meiotic divisions, their duration, and variability within and between trees inL. laricinawas similar to those reported forL. decidua, L. kaempferi, L. sibirica, andL. eurolepis.Deviation from the normal pattern occurred infrequently. In six trees the "resting diplotene" of winter was interrupted on one occasion and some male strobili had a "delayed meiosis" which occurred several days after meiosis in all other sampled strobili. Abnormal chromosome separations were observed on a few occasions; these consisted mostly of lagging chromosomes, a common abnormality inLarixmeiosis. The implications for pollen development and seed yield are discussed.La microsporogénèse chezLarix laricinadans l'est de Terre-Neuve a été étudiée à intervalles hebdomadaires d'octobre à avril, pendant quatre années successives. Les strobiles mâles étaient fixés dans un mélange 3 : 1 d'éthanol – acide propionique, colorés au carmin alcoolique et écrasés dans l'acide acétique 45%.

ISSN:0008-4026    

DOI:10.1139/b82-103

出版商:NRC Research Press    

年代:1982

数据来源: NRC

摘要:

The spikelets ofAndropogon gerardiioccur in pairs, one sessile and one pedicellate. The first glume of the sessile spikelet is bikeeled. The fertile lemma of the sessile spikelet is awned and the awn develops after the lemma has been initiated. The paleas of both spikelets initiate at two positions, are bikeeled, and, on occasion, are two-parted as a result of an interrupted zone of initiation. Each functional lodicule ofA. gerardiiis developmentally similar to one keel of the palea that has become thickened as a result of activity of an adaxial meristem. The spikelet pairs develop from one primordium. At early stages, spikelet pair primordia about each other along the inflorescence axis and the spikelets of a pair are not separated by a pedicel. The pedicel and the axis of the inflorescence develop through intercalary growth. Differences between appendages in the spikelet ofA. gerardiican be viewed as the result of differing amounts of developmental activity (apical growth, marginal meristem, adaxial meristem) common to phyllomic structures. These common developmental activities are, in turn, the result of certain patterns of cell division and cell growth. The evolution of form thus results from alteration of common developmental events. When viewed in such a manner, the evolution of form is seen to be the modification of the informational entropy in an organism. With evolution, there are increases and decreases in informational entropy but, generally speaking, more complex organisms have higher entropy.

ISSN:0008-4026    

DOI:10.1139/b82-104

出版商:NRC Research Press    

年代:1982

数据来源: NRC

摘要:

Staminate and hermaphroditic flowers show an hypogynous disc which is composed of two separate parts, an apical and a basal part. These histologic zones should be considered as nectaries. They differ by their position, their shape, and the content and state of differentiation of their cells. Basal nectaries are not vascularized but phloem bundles reach the tip of the disc. Initiation of nectariferous tissue occurs after that of the floral parts. The basal nectaries appear first but the number of cells still increases during the formation of the apical part of the disc. Both basal and apical nectaries have a superficial origin. Numerous anomocytic stomata are present especially on the surface of the apical nectaries; they are rounded and keep their stomatal pores open. On basal nectaries, however, they occur much less frequently.

ISSN:0008-4026    

DOI:10.1139/b82-105

出版商:NRC Research Press    

年代:1982

数据来源: NRC

摘要:

Plants that are infected with fungi of the speciesVerticilliumfrequently develop foliar disease symptoms which may include one or more of the following: flaccidity, drying, chlorosis leading to necrosis, vascular browning, epinasty, and leaf abscission. A number of ultrastructural and chemical alterations occur in the vascular tissues of such leaves: deposition of brown pigments, coating of xylem vessel walls with abnormal material (i.e., lipid-rich coatings or fibrillar coatings), plugging of xylem vessels with gums, gels or tyloses, degeneration of parenchyma cells, and accumulation of abnormal electron dense materials in primary and secondary cell walls. Different host–parasite combinations exhibit different leaf symptoms and different cytological alterations. The purpose of the present survey was to determine whether the extent of any of the possible vascular alterations in leaves could be correlated with the wilting tendency of the host.Chrysanthemums, snapdragons, eggplants, sunflowers, potatoes, sycamore maples and hedge maples were infected withV. dahliae; alfalfa and hops were infected withV. albo-atrum. When leaf symptoms were well advanced, samples were taken from the major lateral leaf veins and were prepared for light (LM) and transmission electron microscopy (TEM) or scanning electron microscopy (SEM). The various types of alterations in the vascular tissues were identified by a correlated LM–TEM method and (or) SEM analysis and for each sample vein the proportion of vessels affected by each type of alteration was calculated. Four leaf samples, each from different plants, were analysed for each host. The visual symptoms, including vascular browning, were estimated subjectively. The degree of leaf flaccidity was correlated positively with the proportion of lipid-coated vessels and inversely with the degree of vascular browning. No other correlations were observed.

ISSN:0008-4026    

DOI:10.1139/b82-106

出版商:NRC Research Press    

年代:1982

数据来源: NRC