摘要:

The proportion of peak I (molecular weight > 107) to peak II (molecular weight ca. 105) invertase increases in the leaves of common wheat,Triticum aestivumL. emend. Thell ssp.vulgare, as they age. Elongating leaf tissues produced at 21 °C contain much higher levels of peak I plus peak II invertase than do mature leaves. Most of this invertase is peak II material. In cold-hardened plants, old leaf tissues contain much more peak I plus peak II invertase than do young or elongating leaves. Such old leaves contain mostly peak I invertase.The ratio of peak I to peak II invertase in the leaves or roots from cold-hardened plants is higher than that from comparable tissues of non-hardened plants.Earlier data showed that the ratios of the quantities of peak I to peak II invertase are highly correlated with cold hardiness when a group of common wheats grown under the same hardening conditions are compared but not when a single variety is grown under different hardening conditions. The present data show that the ratio of peak I to peak II invertase changes as the tissues age. Consequently, comparing the ratios of peak I with peak II invertase in plants consisting of tissues that are not of comparable ages will confound the effects of tissue age and tissue cold hardiness. Good correlations between cold hardiness and the ratio of peak I to peak II invertase cannot be expected and were not found in earlier work under such conditions.

ISSN:0008-4026    

DOI:10.1139/b82-001

出版商:NRC Research Press    

年代:1982

数据来源: NRC

摘要:

Evidence from cultured and soil-borne mycelium clearly indicates that the widespread mycorrhizal symbiont (or symbionts) known as the E-strain is an ascomycete anamorph. The evidence includes regular septation, the presence of Woronin bodies and injury- and age-induced septal plugs, sensitivity to benomyl, hyphal fusions, mode of hyphal repair, and morphology of the mycorrhizae. Isolates varied in the presence or absence of chlamydospores, pigmentation, growth rates, amount of aerial mycelium, and amount of hyphal ornamentation. It is uncertain whether one or more taxa is currently included in the E-strain concept.

ISSN:0008-4026    

DOI:10.1139/b82-002

出版商:NRC Research Press    

年代:1982

数据来源: NRC

摘要:

Aging of thalli of two microsclerotial strains ofVerticillium albo-atrumisolated from tomato and avocado in Morocco affected microconidia viability and the phenotype of regenerated thalli. The percentage of regeneration of microconidia harvested in thalli of increasing age was first high; it diminished to a minimum, then increased again reaching high values. The age of cultures for which these variations arose as well as the different values of percentage of regeneration were dependent on the isolate and on culture conditions. Microconidia from young cultures produced only wild thalli; microconidia from old cultures also regenerated stable morphological variants, which increased in number with the age of the culture. Variants were numerous only when the age of cultures was equal or higher than the age for which the percentage of regeneration was minimum; they probably arose from late forming microconidia on old thalli.

ISSN:0008-4026    

DOI:10.1139/b82-003

出版商:NRC Research Press    

年代:1982

数据来源: NRC

摘要:

Conidia inNomuraea rileyiare produced basipetally from a phialide apex. Production of primary and all successive conidia appears to beenteroblastic, and only the inner, newly formed wall layer of the phialide surrounds developing conidia. Conidium formation ceases as layers of inner wall material accumulate at the phialide apex. In some cases, a pluglike structure resembling a Woronin body may cause cessation of conidiogenesis. Conidia are delimited by formation of a double septum. Since one half of the septum forms the base of the "older" conidium and the other half forms the apex of the next conidium, separation of successive conidia isschizolytic. Plasmalemmasomes, lomasomes, and smooth endoplasmic reticulum are often seen in association with septa and walls of conidiogenous cells. Transverse fibrils may be observed in some walls. Extensive vacuolization is common in older cells. Glycogen is present in conidiogenous cells and in conidia, which become very electron dense as they mature. An extranuclear plaque, an ascomycetous characteristic, may be observed on the nuclear envelope.

ISSN:0008-4026    

DOI:10.1139/b82-004

出版商:NRC Research Press    

年代:1982

数据来源: NRC

摘要:

The effects ofFusarium oxysporumf. sp.apiion celery seed germination were investigated with the hope of developing a germ-plasm screening procedure with seeds. Seeds of celery lines known to exhibit a range of disease responses to the pathogen as whole plants were inoculated with two different virulence types and in two ways: (1) spore–mycelial suspensions in potato dextrose broth (PDB), and (2) spore–mycelial suspensions in sterile H2O. Inoculum in PDB retarded germination in all celery lines and the relative degree of this retardation was congruent with virulence of the pathogen and, in general, relative retardation of germination was also in agreement with whole-plant disease response. Inoculum in H2O stimulated germination and the degree of stimulation also appeared related to degree of whole-plant disease response. Extracts from disease lesions incited byF. oxysporumf. sp.apiion celery exerted a dose-dependent inhibition of germination but filtrates from 14-day-old cultures in PDB had no significant effect.

ISSN:0008-4026    

DOI:10.1139/b82-005

出版商:NRC Research Press    

年代:1982

数据来源: NRC

摘要:

An undescribed species ofInocybe,I. immigranssp. nov., has been encountered several times on mine wastes in north-eastern and east-central Ontario. It is characterized by large smooth basidiospores, a dark entirely cystidiate bulbous stipe, and a brown scaly pileus. It is thought to be ectomycorrhizal and has been collected in association withBetula papyrifera, Populus balsamifera, andSalixspp.

ISSN:0008-4026    

DOI:10.1139/b82-006

出版商:NRC Research Press    

年代:1982

数据来源: NRC

摘要:

Morphological characteristics and biomass allocation were examined for two species ofTyphain a small pond.Typha latifoliadiffered fromT. angustifoliain having shorter leaf height, wider leaves, greater leaf surface area, greater allocation to leaves, greater number of smaller rhizomes, greater allocation to vegetative reproduction, smaller allocation to sexual reproduction, and fewer number of flowering plants. For both species, those plants growing in deeper water had taller leaves, a greater allocation to leaves, and a decreased allocation to sexual and vegetative reproduction. Previous studies of these populations have demonstrated that these two species are segregated according to water depth withT. latifoliabeing competitively superior in shallow water (less than 15 cm) butT. angustifoliahaving the potential to grow in deeper water thanT. latifolia. Results from this study indicate thatT. latifoliais competitively superior in shallow water because of its greater leaf surface area but thatT. angustifolia's tall, narrow leaves and large rhizome storage permit it to grow in deeper water thanT. latifolia. The greater amount of sexual reproduction inT. angustifoliais correlated with its more restricted distribution and fugitive nature.

ISSN:0008-4026    

DOI:10.1139/b82-007

出版商:NRC Research Press    

年代:1982

数据来源: NRC

摘要:

Epipelic and planktonic algal communities have been examined periodically for 3 years from four tundra ponds which have very low pH values (1.8–3.6) and high heavy metal concentrations due to long-term fumigation by sulphur dioxide and sulphuric acid aerosols from nearby lignite burns. These communities have been compared with those of control ponds which are situated further from the burns and have alkaline waters (pH 8) due to calcareous marl soils. The 90 species identified from the control ponds are members of nine classes of algae. In contrast, 14 species have been observed in the fumigated ponds which are representatives of four classes, the Chlorophyceae, Euglenophyceae, Bacillariophyceae, and Cryptophyceae. The plankton of the control ponds is typical of tundra ponds in that it is dominated by small flagellates, particularly the cryptomonadChroomonas minuta. Diatoms such asAmphora, NaviculaandSurirellaspecies, are the major components of the epipelic periphyton of these ponds, accounting for 67 to 90% of the biomass. Most of the primary productivity and biomass of the algae in the acidified ponds is benthic (3.7 versus 0.17 mg C m−2 h−1for epipelon and plankton, respectively). The dominant species in the fumigated ponds includeChlamydomonas acidophila, Euglena mutabilis, Nitzschia communis, Eunotia arcus, andEunotia glacialis. Fine structural examination ofEuglenaandNitzschiaindicates that these species are healthy under conditions of pH 1.8 and high heavy metals. These results show that the flora of the fumigated ponds is atypical of tundra ponds but rather is similar to that of very acidic temperate waters such as those draining coal-mined areas or volcanic lakes.

ISSN:0008-4026    

DOI:10.1139/b82-008

出版商:NRC Research Press    

年代:1982

数据来源: NRC

摘要:

The leakage of total electrolytes, potassium, calcium, sugars, and amino acids from primary leaf discs ofPhaseolus vulgarisL. cv. Seafarer (ozone susceptible) and cv. Goldcrop (ozone tolerant) was monitored following exposure to 40 parts per hundred million (pphm) ozone for 4 h. Significant differences in cultivar response were not detected until 24 h after exposure. At that time, leakage from cv. Seafarer leaves was 220% for total electrolytes, 230% for calcium, 260% for potassium and sugars, and 400% for amino acids relative to controls, whereas the leakage from cv. Goldcrop leaves remained at control levels. The water-soluble sugar and free amino acid content of a leaf homogenate also increased at the 24-h sampling time. These accumulations may result from a reduced rate of phloem translocation. Rates of leakage and leaf-solute contents returned to control levels by 48 and 72 h after exposure.Kinetic analysis of solute efflux from leaf discs sampled from both cultivars immediately after ozone exposure indicated that these leaves contained an increased quantity of solutes which could be rapidly leached within 0.5 h. However, the subsequent linear rate of leakage between 0.5 and 4 h did not increase except in leaf discs sampled from cv. Seafarer 24 h after exposure. The results are discussed in relation to the mechanism of ozone injury in cv. Seafarer and the basis of ozone tolerance in the cv. Goldcrop.

ISSN:0008-4026    

DOI:10.1139/b82-009

出版商:NRC Research Press    

年代:1982

数据来源: NRC

摘要:

Mutants with altered sexual reproduction were isolated from a homothallic wild-type strain ofNectria haematococca(Berk. & Br.) Wr. and genetically analysed. Most were self- and inter-sterile but some were interfertile and were used to improve genetic analysis by allowing an easy detection of hybrid perithecia. The study of these mutants also provides information about various aspects of the perithecial development in this organism.

ISSN:0008-4026    

DOI:10.1139/b82-010

出版商:NRC Research Press    

年代:1982

数据来源: NRC