摘要:

A species ofHelicostylumCorda isolated from samples of soil (pH 6.0–8.0)collected from Lucknow (U.P.), India, was found to be different from all the known species of this genus and has been described asHelicostylum lucknowenseRai, Tewari and Mukerji n. sp.

ISSN:0008-4026    

DOI:10.1139/b61-113

出版商:NRC Research Press    

年代:1961

数据来源: NRC

摘要:

Healthy and needle-blighted eastern white pine trees (Pinus strobusL.) were intergrafted in the forest using bottle and cleft crown graft techniques. The grafts were made in four combinations of diseased and healthy scions and stock branches and at three different stages of development of the graft components. High percentages of successful grafts were obtained when the partner combinations included healthy scions and when the grafting was done in early May with active top growth just beginning in both scions and stock. Fewer grafts survived when diseased scions were employed and when the field grafting was carried out with dormant-collected scions or with scions and stock both possessing advanced new growth.Each grafted partner retained its original identity. Needle-blight symptoms appeared simultaneously on diseased scions and their mother trees, while the healthy stock trees remained unaffected. Conversely, healthy scions and their mother trees were unaffected while the diseased stock trees displayed the needle-blight symptoms on their foliage. No disease symptoms were transmitted by stem grafting. A search revealed that perennially needle-blighted trees were joined to neighboring healthy trees by natural root grafts, and that there was no visible communication of the disease symptoms. Additional evidence has been presented to show that needle blight is nonparasitic in etiology and that susceptibility to needle breakdown is inherent in the individual.

ISSN:0008-4026    

DOI:10.1139/b61-114

出版商:NRC Research Press    

年代:1961

数据来源: NRC

摘要:

The Monteregian Hills are a series of eight mountains, intrusive in nature, which form a distinct petrographical province in the St. Lawrence Lowlands of Southern Quebec. Mont St. Hilaire, one of the larger members of the group, was bequeathed to McGill University as a natural area for scientific research in 1959 by the late Brigadier A. Hamilton Gault. During a survey of the natural resources of the mountain throughout the summer of 1959, botanical investigations of the flora and vegetation were conducted. The present report is the first in a series that will present the results of these studies. It is concerned with the general characteristics of the mountain and the known existing flora.

ISSN:0008-4026    

DOI:10.1139/b61-115

出版商:NRC Research Press    

年代:1961

数据来源: NRC

摘要:

First seedling leaves of Little Club (susceptible), Khapli I (moderately susceptible), and Khapli (resistant) wheats were inoculated withPuccinia graminis triticiErikss. and Henn. (Race 15B). Ascorbic (AA) and dehydroascorbic (DHA) acids and glutathione (GSH) were measured at 1–2 day intervals after inoculation until after sporulation. After infection, AA and DHA increased in Little Club and decreased in Khapli. In Khapli the DHA/AA ratio rose sharply 6–8 days after inoculation; in Little Club a similar rise occurred 15–16 days after inoculation. In Khapli I and Little Club, but not in Khapli, GSH increased sharply when sporulation occurred. AA was not detected in uredospores, but DHA was. Oxidized glutathione was not detected in healthy or infected leaves but was present in uredospores. The results are discussed briefly in relation to the changes in auxin content and redox potentials caused by rust infection.

ISSN:0008-4026    

DOI:10.1139/b61-116

出版商:NRC Research Press    

年代:1961

数据来源: NRC

摘要:

The leaves of homozygous nec. 1 plants (a single-gene, necrotic maize mutant) develop visible necrotic symptoms when they are exposed to light for several days. Extensive analysis has failed to reveal any difference in chemical composition between leaves of normal plants and of homozygous nec. 1 plants before the necrotic symptoms are visible (prenecrotic leaves). Treatment of nec. 1 seedlings with various metabolites (B vitamins, purines, pyrimidines, amino acids, etc.) did not prevent the appearance of necrosis. The rate of photosynthesis of prenecrotic leaves is normal at low light intensities but only 20 to50% of normal at saturating light intensity. C14O2feeding experiments indicate that the photosynthetic carbon-fixing reactions function normally in the mutant. Hill reaction rates are also similar in mutant and normal plants, as is the metabolism of labelled inorganic phosphate. 3-(p-Chlorophenyl)-1,1-dimethylurea, which specifically inhibits photosynthesis to the extent of about 90%, delays the onset of visible necrotic damage and reduces the severity of subsequent necrotic symptoms. It is suggested that the basic lesion in nec. 1 plants lies in a reaction associated with photosynthesis and that it causes the accumulation of one or more toxic substances. These materials lower the rate of photosynthesis and damage cell membranes. The necrotic phenotype would appear to be the result of the breakdown of cell compartmentalization.

ISSN:0008-4026    

DOI:10.1139/b61-117

出版商:NRC Research Press    

年代:1961

数据来源: NRC

摘要:

The dry weight of leaf disks (2.8 mm in diameter) bearing pustules of stem rust and cut from primary leaves of Little Club wheat increased up to 2.5-fold, but the respective weights of host and parasite cannot be measured. By removal of the ectoparasitic mycelium ofErysipheit was shown that approximately half of the increase in weight at infections of this organism on barley leaves was contributed by the fungus and half by the host.At infections of stem rust on Little Club there was a striking increase in total N per gram fresh weight and an increase in the ratio of soluble to insoluble N. Quantitative paper chromatographic analyses revealed a fourfold increase in free amino acids and nearly a twofold increase in protein amino acids per gram fresh weight by 9 days after inoculation. The most striking increases occurred in free glutamine, γ-aminobutyric acid, threonine, and those amino acids present only in trace amounts before inoculation, particularly the basic and aromatic acids. Only slight and transitory increases in N occurred at infections on Khapli and the infected leaves quickly reached a stage at which soluble and insoluble N and the ratios of soluble N to insoluble N and free to protein amino acids declined drastically. In Khapli, well-defined increases occurred in free glutamine and γ-aminobutyric acid. Particularly striking decreases occurred in glutamate, serine, threonine, glycine, and the leucines. The results are discussed.

ISSN:0008-4026    

DOI:10.1139/b61-118

出版商:NRC Research Press    

年代:1961

数据来源: NRC

摘要:

Fungus isolation attempts, made from samples taken at 2-ft intervals in the stems of 40 lodgepole pines (Pinus contortaDougl.), gave 1362 cultures. Sample trees were located at two sites and averaged 82.5 and 63.9 years of age. In malt agar cultureTympanis hypopodiaNyl. and theCoryne sarcoidescomplex were slightly antagonistic toStereum pini(Schleich. ex Fr.) Fr. Both microfungi caused small weight losses in pine wood blocks and, when inoculated in advance on test blocks, reduced the decay caused byS. pini. Retinocyclus abietis(Crouan) Groves & Wells caused no weight loss but increased the decay attributable toS. pini. Tympanis hypopodiaandC. sarcoidescomplex were more or less restricted to the lower heartwood of the trees. There was some evidence of a succession of fungi in the trees.

ISSN:0008-4026    

DOI:10.1139/b61-119

出版商:NRC Research Press    

年代:1961

数据来源: NRC

摘要:

Virus entities in cucumber associated with cherry yellows, green ring mottle, and necrotic ring spot of sour cherry; tatter leaf of sweet cherry; and prune dwarf were found to be serologically related but not identical. The virus antigens were compared in gel-diffusion precipitin tests with antisera prepared from both cucumber leaves and infected cherry petals.

ISSN:0008-4026    

DOI:10.1139/b61-120

出版商:NRC Research Press    

年代:1961

数据来源: NRC

摘要:

Wang (Can. J. Botany,38, 635–642 (1960)) concluded that the accumulation of radioactivity observed on radioautographs at infection sites on rusted leaves fed with C14-labelled substances was 'apparent' rather than real. The ‘accumulation ratio’ is defined as the ratio of the specific activities (c.p.m./mg dry weight of intact tissue) of rust-infected to uninfected areas of infected leaves. Theoretical considerations relating to the radioautography of leaves labelled with C14and to the measurement of ‘accumulation ratios’ by extraction of C14-labelled substances from rusted and uninfected segments of infected leaves, as well as experimental data, show that Wang's conclusion is not generally applicable.Experimentally, it was shown using polymethacrylate C14sources that differences in distance between sources and X-ray film of the order of 100 μ had no effect on the intensity of autoradiographs. Rust-infected leaves, fed with radioactive glucose, were radiographed between X-ray plates. Localization of radioactivity at infection sites was observed on both ‘dorsal’ and ‘ventral’ radiographs, indicating a real accumulation per unit area. Ventral were more radioactive than dorsal surfaces. The main development of the fungus occurred on the former. Radioautography revealed that C14from glucose-1-C14, glucose-6-C14, and uniformly labelled glucose fed to excised wheat leaves became localized at 10-day-old rust infections in 2 hours. ‘Accumulation ratios’ calculated from the specific activity of leaf segments remained close to 1.0 for at least 6 hours after introduction of the tracer, but increased to more than 2 after 24 hours. When ‘accumulation ratios’ were calculated from the specific activities of individual pustules (excised with a punch 1 mm in diameter) and interpustular disks, values greater than 1 were observed in 2 hours, thus confirming the results of autoradiography. Differences between the ‘accumulation ratios’ observed with glucose-6-C14and glucose-1-C14were consistent with an increased role of the pentose phosphate pathway at infection sites. Incorporation of C14from uniformly labelled glucose into the alcohol-insoluble fraction of rusted leaf segments was 2.5-fold that in uninfected segments in 6 hours and 3.65-fold in 24 hours. The humin formed during hydrochloric acid hydrolysis accounted for approximately 50% of the activity of the alcohol-insoluble material. The ‘accumulation ratio’ for the alcohol-soluble material was only 1.56 after 24 hours.All the results support the view (Shaw and Samborski, Can. J. Botany,34, 389–405 (1956)) that there is a quantitative, metabolically dependent accumulation of C14from radioactive glucose at vigorous rust infections. The relative roles of fungus and host in this process are discussed briefly.

ISSN:0008-4026    

DOI:10.1139/b61-121

出版商:NRC Research Press    

年代:1961

数据来源: NRC

摘要:

Cultural studies, including observations on anastomoses, were undertaken on host-specific forms ofMarssonina populi(Lib.) Magn. The fungus appears to consist of a highly variable and unstable series of forms differing in both morphological and cultural characteristics. Cytological studies have indicated that the pathogen is a uninucleate fungus. Anastomoses, evident between most of the forms examined, frequently resulted in dicaryotization of one of the cells but the dicaryotic condition was not perpetuated.

ISSN:0008-4026    

DOI:10.1139/b61-122

出版商:NRC Research Press    

年代:1961

数据来源: NRC