摘要:

In the male-fertile line of pepper, microsporogenesis and pollen development are normal. During meiosis, the meiocytes become encased in callose and a locular cavity forms. A rudimentary pollen wall, preceded by primexine deposition, is formed at the tetrad stage around the microspores before their release from the callose. The tapetum remains peripheral in the locule until the vacuolate pollen stage when it disappears. The sporogenous cells of the cytoplasmic male-sterile line complete meiosis, and the callose-encased microspores also deposit a primexine. Further development of the microspores is arrested. Before and during meiosis the tapetal cells become highly vacuolate and remain appressed to the meiocytes; a locular cavity is not formed. After primexine deposition, the tetrads of microspores, which are still encased in callose, seem to collapse as they are encroached upon by the vacuolate tapetum. After abortion of the microspores the outer tapetal layer degenerates, followed by the inner tapetal layer. The aborted mass late in anther development consists of crushed microspore tetrads, primary walls of the sporogenous cells and tapetum, callose, and the collapsed tapetum. The manner of abortion in pepper is compared with previously described mechanisms.

ISSN:0008-4026    

DOI:10.1139/b74-056

出版商:NRC Research Press    

年代:1974

数据来源: NRC

摘要:

Synchronous conidiation was induced in pure cultures ofUlocladium atrumby removal of a dialysis membrane overlay beneath which vegetative mycelium had been allowed to grow for 24 h on a solid nutrient agar medium. Samples takenand 6 h after the induction of sporulation contained numerous conidiophores with conidial initials in the very earliest stages of formation. Examination of sections of such conidiophores with the electron microscope revealed no suggestion of a discontinuity in the wall between the conidiophore and the conidial initial. We conclude that conidiation inUlocladium atrumis holoblastic.

ISSN:0008-4026    

DOI:10.1139/b74-057

出版商:NRC Research Press    

年代:1974

数据来源: NRC

摘要:

Viability of sporangia ofPseudoperonospora cubensisandPhytophthora infestanswas greatly reduced when sporangia were wetted for a period too short to ensure germination and then allowed to dry out (WDR treatment). No morphological changes were detected in WDR-treated sporangia by microscopic examinations, but when examined under electron microscope they exhibited partial or complete alterations of the mitochondrial inner membrane integrity, some deterioration of the plasmalemma, and extensive vacuolization.Water uptake was not affected but oxygen uptake was totally inhibited in WDR-treated sporangia and previously labeled sporangia exhibited increased leakage. No incorporation of14C-leucine (into proteins) and32P-orthophosphate (into nucleic acids) occurred as a result of the treatment. Adding various sugars, alcohols, and adenosine triphosphate (ATP) to the treated sporangia did not restore their viability.It was suggested that the water stress exerted by WDR treatment primarily caused a deterioration of the mitochondrial membrane integrity, which in turn probably led to the other phenomena listed above.

ISSN:0008-4026    

DOI:10.1139/b74-058

出版商:NRC Research Press    

年代:1974

数据来源: NRC

摘要:

Field studies were made of eight terrestrial orchid species of the Thunder Bay region during their active growing period. In four of them roots were examined for infection, then isolation and identification of endophytes attempted.Seeds were collected from all species and, along with those of two alien ones, were grown on various media in axenic culture. Their germination and development were studied and described.Seeds were also tested in dixenic cultures with locally isolated endophytes and four fungi known to be good symbionts with other orchids. The nature of infection was finally assessed and discussed.In the field the roots of mature plants of the orchid species differed in their degree of infection and reaction to their endophytes. Only two species ofRhizoctoniawere isolated. These are described.In axenic culture, germination of some species was affected by the organic (and inorganic) components of the media, in others it was not. For growth they all responded differently to such components, but most were intolerant of casamino acids, yeast extract, and potato extract. Generally there seemed to be a direct correlation between percentage of germination and amounts of subsequent growth, but a less defined one with the number of cells per seed.In dixenic cultures the orchids responded differently also to the fungi. Their reaction to infection had no relation to their ability to germinate on poor media or to germinate and grow on richer ones. Only one good symbiotic association was established. It was betweenGoodyera oblongifoliafrom British Columbia and Rs10, a rice pathogen from Malaysia.The results and their implications are briefly discussed.

ISSN:0008-4026    

DOI:10.1139/b74-059

出版商:NRC Research Press    

年代:1974

数据来源: NRC

摘要:

Seventy-two potato tubers of 106 tested from plants exposed 1 year in a field were found infected with potato virus S (PVS) in different tests. Ninety-three percent of these were detected by tuber juice inoculation toNicotiana debneyiDomin. and 90% by serology of 30-cm plants grown from an eye of such tubers. Sap inoculation toN. debneyiof the same young plants proved to be 96% efficient in detecting the virus, and serological tests at bloom stage were the most efficient of all the tests compared.Tests done on all tubers from 18 plants currently infected with PVS showed that 103 of 116 (89%) were infected, and virtually all eyes from 68 infected tubers produced infected plants.Three years of field trials at Fredericton on the spread of PVS showed that the virus moved into virus-free varieties independently of potato virus X (PVX). In 1970, leaf tests showed that virus-free Netted Gems became 12% infected with PVS; in 1971, spread into Green Mountain, Kennebec, and Sebago was 57, 19, and 9%, respectively; and in 1972, 14% spread occurred in Green Mountain and none in Kennebec or Sebago.Greenhouse experiments on transmission of PVS to potato byMyzus persicae(Sulz.) resulted in 3 of 87 (3.4%) plants becoming infected. Other tests with potato virus Y (PVY) to tobacco,Nicotiana tabacumL. var. Samsun, resulted in 83% transmission.

ISSN:0008-4026    

DOI:10.1139/b74-060

出版商:NRC Research Press    

年代:1974

数据来源: NRC

摘要:

Investigation ofPeziza badiaandP. badio-confusabased on herbarium specimens of North American material emphasized that these previously confused species can be distinguished by ascospore ornamentation and usually by fruiting habit, but not solely on ascospore length and width, which a statistical analysis indicated was unreliable for these species. Except at their northern limits,P. badiais an autumnal andP. badio-confusaa vernal species.

ISSN:0008-4026    

DOI:10.1139/b74-061

出版商:NRC Research Press    

年代:1974

数据来源: NRC

摘要:

The histological study of thede novoformation of shoot and root meristems from inter-nodal segments ofTorenia fournierishowed that buds are formed exclusively from epidermal cells and roots from endogenous perivascular tissue. It seems that there are no particular epidermal cells which are preferentially involved in the initiation of buds. This study showed the different and apparently specific potentialities of superficial and endogenous tissues.

ISSN:0008-4026    

DOI:10.1139/b74-062

出版商:NRC Research Press    

年代:1974

数据来源: NRC

摘要:

The volatile oils of the leaves and twigs of alpine fir, and western and eastern Canadian balsam fir were analyzed by gas–liquid chromatography. Many qualitative similarities were found and the within-tree and tree-to-tree variation of the quantitative terpene composition of the leaf oil was sufficiently small to permit a chemosystematic study.Abies lasiocarpaandA. balsameamay be differentiated by the relative amounts of β-pinene, 3-carene, β-phellandrene,trans-ocimene, piperitone, methyl thymol, and thymol. Consistent quantitative differences were also found between eastern and westernA. balsamea, and the populations in the Lesser Slave Lake and Battle Lake regions of central Alberta gave intermediate terpene data, which suggests introgression betweenA. lasiocarpaand westernA. balsamea. Thus a cline betweenA. lasiocarpaandA. balsamea, with western balsam fir populations as bridge, may have existed after the last glaciation. The alpine fir populations of southern Alberta, and eastern and central British Columbia gave uniform terpene data, but five trees sampled on Green Mountain, Vancouver Island, gave significantly different terpene data. These results were substantiated by morphological characters as well as twig oil analysis, but the latter two methods gave less consistent data than leaf oil analysis.

ISSN:0008-4026    

DOI:10.1139/b74-063

出版商:NRC Research Press    

年代:1974

数据来源: NRC

摘要:

Seventeen samples were collected at regular intervals from September 1970 to December 1971 from four sites on lake St. Louis; these stations received their water either from the St. Lawrence River, the Ottawa River, or both. For each species and sample of the 178 phytoplankton entities found, the number of cells per liter was estimated. A general view of the distribution of plankton organisms at each station is given as well as the seasonal variation of the major systematic groups and the dominant species.

ISSN:0008-4026    

DOI:10.1139/b74-064

出版商:NRC Research Press    

年代:1974

数据来源: NRC

摘要:

Descriptions of major morphological features including those of the pollen, chromosome counts, and distribution data of the taxa of the family Urticaceae found in Canada are presented. There has been confusion in the species epithets applied to the genusUrtica. This study indicates that there are only three taxa in Canada:U. urens, 2n = 26;U. dioicassp.dioica, 2n = 52; andU. dioicassp.gracilis, 2n = 26 and 52. The tetraploidU. dioicassp.gracilisranges from the Rocky Mountains to the west coast while the diploid race occurs from the eastern side of the Rocky Mountains to the east coast. Artificial hybrids within the diploid race ofUrtica dioicassp.gracilisproduced F1plants with plenty of fertile seeds while a cross between a diploid and a tetraploid race of this taxon produced F1plants with irregular chromosome pairing in the pollen mother cells and no seed set. The introducedU. dioicassp.dioicaranges from Ontario to Newfoundland and the annualU. urensis widely scattered from the Yukon to Newfoundland.Laportea canadensisandPilea pumilawere found to have 26 somatic chromosomes;Boehmeria cylindrica, 28; andParietaria pensylvanica, 16.

ISSN:0008-4026    

DOI:10.1139/b74-065

出版商:NRC Research Press    

年代:1974

数据来源: NRC