摘要:

Detached tobacco leaves were placed for six hours on solutions of C14labelled glucose and glucose-1-phosphate. At the end of this time leaves were extracted with boiling 80% ethanol and the activities of their various carbohydrate fractions were determined. The specific activities of both glucose and fructose moieties of sucrose were found to be high and very close one to another, while that of the free fructose was low. From this it has been concluded that the fructose component of sucrose is derived from the glucose introduced and not from the free fructose present in leaves. Low activity in starch observed in photosynthesizing leaves indicates preferential transformation of the glucose introduced into sucrose and not into starch. Moreover, respiration of labelled glucose ought to produce labelled carbon dioxide, and after a period of photosynthesis, labelled starch. The isolated starch contained only a small amount of activity indicating that, in light, sugars were not utilized in respiration to any great extent. Moreover, they did in darkness, as the carbon dioxide evolved was very radioactive.

ISSN:0008-4026    

DOI:10.1139/b54-032

出版商:NRC Research Press    

年代:1954

数据来源: NRC

摘要:

Twenty-four plants of barberry,Berberis vulgarisL., were inoculated with sporidia derived from several collections of race 15B ofPuccinia graminisvar.triticiErikss. & Henn. Only five small pustules of aecia were produced on these plants; all other infections were limited to small necrotic spots or very small pustules of pycnia.

ISSN:0008-4026    

DOI:10.1139/b54-033

出版商:NRC Research Press    

年代:1954

数据来源: NRC

摘要:

Plant residues were mixed with moistened soils and the mixtures incubated at room temperature. Samples were taken at intervals of several days, steam sterilized, and used as substrates in the Lees respirometer for measurements of oxygen uptake byRhizobium meliloti. Rhizobia were active in the soils and their activity was stimulated by addition of ordinary plant residues. It was found that the shorter the incubation period of the soil – plant residues mixture, the greater was the increase in oxygen uptake over that obtained when the soil alone was used as substrate. The Lees respirometer was found to be a convenient apparatus for measurements of oxygen uptake by soil microflora.

ISSN:0008-4026    

DOI:10.1139/b54-034

出版商:NRC Research Press    

年代:1954

数据来源: NRC

摘要:

An actinophage forStreptomyces scabieswas isolated from soil surrounding scab infected potatoes. Tested against 15 scab producingStreptomycescultures isolated from scab lesions, 13 were lysed, one partially lysed, and one was resistant. Against 15 nonscab producing strains of actinomycetes, also isolated from scab lesions, 13 were not lysed and 2 showed evidence of partial lysis. Tested against actinomycete cultures isolated from soil, the phage was less specific and the results were inconclusive. Lack of phage specificity is attributed to variation amongStreptomycescultures.

ISSN:0008-4026    

DOI:10.1139/b54-035

出版商:NRC Research Press    

年代:1954

数据来源: NRC

摘要:

Seedlings ofPinus sylvestrisL. andAlnus incana(L.) Moench. from two widely different latitudes were grown under two different photoperiods, but otherwise under optimum conditions. Under continuous light the seedlings from a far northern latitude grew better than those from a more southern latitude. This situation was reversed under short photoperiods. Since the days of the growing season at the northern latitude are extremely long and those at the southern latitude relatively short, the difference in growth of the seedlings is explained as being the result of heritable adaptation of the trees. The experimental results thus support the theory that within tree species there are "photoperiodic ecotypes" which during evolution have adapted themselves to the photoclimate of their environment.

ISSN:0008-4026    

DOI:10.1139/b54-036

出版商:NRC Research Press    

年代:1954

数据来源: NRC

摘要:

The microcyclic species ofPucciniaon Saxifragaceae are revised in the light of abundant recent collections. Recombinations or new varieties include:P.asiaticavar.tiarellae,P.heucheraevar.chrysosplenii,P.h. var.austroberingiana,P.h. var.saxifragae,P.h. var.lithophragmae,P.pazschkeivar.heterisiae,P.p. var.tricuspidatae,P.p. var.huteri,P.p. var.jueliana,P.p. var.oppositifoliae. The basic species appears to beP.tottoriensis, whence three evolutionary lines have given rise to: (i)P.asiatica,P.saxifragae–ciliatae, andP.laurentiana; (ii)P.heucheraeandP.pazschkei; (iii)P.fischeriandP.joerstadii. The complex originated in, probably, eastern Asia.P.heucheraevars. developed in Cordilleran North America concurrently with the development of Saxifragaceae in that region. Some varieties ofP.heucheraeoccur on several host genera, providing clues to the comparative ages of species in these genera. Since the varieties ofP.heucheraeandP.pazschkeican be arranged in an evolutionary sequence, clues are available as to the relative ages of various sections ofSaxifraga.

ISSN:0008-4026    

DOI:10.1139/b54-037

出版商:NRC Research Press    

年代:1954

数据来源: NRC

摘要:

When Fischer describedTilletia brevifaciensas the organism causing dwarf bunt of winter wheat, he showed that it was specifically distinct fromT.caries(Fr.) Tul. However, he failed to indicate how his new species was separated from other species ofTilletiaalready described. Some of these species were restudied. It has been found thatTilletia brevifaciensis not specifically distinct fromT.contraversaKühn originally described onAgropyron repens, but also known on other species ofAgropyron. Wheat probably first contracted dwarf bunt in the mountainous areas of Europe, where native species ofAgropyronare found naturally infected byT.contraversa. The pathogen has been introduced into North America.

ISSN:0008-4026    

DOI:10.1139/b54-038

出版商:NRC Research Press    

年代:1954

数据来源: NRC

摘要:

Local damage on the Queen Charlotte Islands to seed of Sitka spruce,Picea sitchensis, has led to the discovery of the causal agent, a new cone rust. At the same time a newChrysomyxaon the one-flowered pyrola,Moneses uniflora, was discovered in the same area. Evidence from observations in the field, from controlled inoculations, and from the similarity of markings on aeciospores and urediniospores has led to the conclusion that the cone rust is the aecial stage of an undescribedChrysomyxa. The rust has been described and namedChrysomyxa monesis. It is feared that the rust may cause serious damage to spruce seed abroad unless its spread is prevented. Surface sterilization of spruce seed before export is therefore recommended.

ISSN:0008-4026    

DOI:10.1139/b54-039

出版商:NRC Research Press    

年代:1954

数据来源: NRC

摘要:

A cytological study ofPyronema confluenshas revealed that only one meiosis occurs in the ascus, and that the haploid chromosome complement is probably 12. Differences in size and staining properties were noted between nuclei of the ascogenous hyphae and paraphyses. Diplotene chromosomes are linearly differentiated into heterochromatic knobs and achromatic intercalary segments that could not be differentiated from the cytoplasm with either basic fuchsin or propiono-carmine.

ISSN:0008-4026    

DOI:10.1139/b54-040

出版商:NRC Research Press    

年代:1954

数据来源: NRC

摘要:

Twelve species ofMelilotuswere intercrossed and the embryology of the hybrids was studied. The species involved in this study areM.alba,M.officinalis,M.suaveolens,M.polonica,M.dentata,M.altissima,M.hirsutus,M.taurica,M.messanensis,M.italica,M.sulcat, andM.speciosa. Among partially compatible crosses,M.officinalis×M.albaproduces the most advanced embryo. Growth of the embryo proceeds normally until about eight days, and more slowly thereafter until the 12th or 13th day, when growth is completely inhibited and the embryo aborts. The reciprocalM.alba×M.officinalisembryo does not grow as large or differentiate as much before aborting by the 11th day. Other crosses, includingM.officinalis×M.suaveolensandM.alba×M.messanensisform a normal proembryo that grows slowly to about the sixth day. The proembryo then loses polarity, organ development becomes abnormal, and the ovule aborts about the 12th day. Aborted embryos are also produced in the cross,M.alba×M.dentata. Reciprocal crosses ofM.suaveolensandM.altissimaandM.altissima×M.polonicaproduce essentially normal embryos up to eight days. These crosses may be sources of economically important germ plasm. Crosses ofM.altissima×M.albaandM.italica×M.altissimaexhibit early embryo abortion. The suspensor becomes necrotic in four or five days and the proembryo floats into the ovule cavity, which contains abundant noncellular endosperm. In the crossM.officinalis×M.altissima, neither the zygote nor the primary endosperm nucleus divides. WhenM.altissimais used as the female parent, the zygote does not divide but the endosperm proliferates. In the cross,M.italica×M.officinalis, neither the zygote nor the endosperm divides. Embryos ofM.italica×M.sulcatagrow for four or five days, but the primary endosperm nucleus does not divide. The hybrid seed ofM.alba×M.suaveolensweighs less than seed of either parent. Although developing ovules are smaller than those ofM.suaveolens×M.alba, the embryo of the former is much larger and more differentiated, and endosperm is more abundant. This relationship between these two compatible species is of particular theoretical interest. Although many of the crosses do not mature viable seed, some embryos develop normally to a point where they would be worthy subjects for culture on nutrient agar.

ISSN:0008-4026    

DOI:10.1139/b54-041

出版商:NRC Research Press    

年代:1954

数据来源: NRC