摘要:

The growth substances were extracted with cold alcohol from the first leaves of uninfected, rusted (wheat), and mildewed (barley) cereal seedlings. The acid ether fractions were chromatographed on paper and the chromatograms were cut into sections which were assayed for growth promoting or inhibiting activity in theAvenacoleoptile straight growth test. The estimated, free, endogenous indoleacetic acid content of uninfected leaves ranged from 0.5 to 3.2 μg. per kilogram fresh weight. In the early stages of infection this decreased, but increased again to from 5 to about 10 μg. per kilogram fresh weight by the 10th day after the inoculation of susceptible hosts. Indoleacetic acid was not detected in ungerminated uredospores of stem rust (race 15B), but two other growth promoting substances appeared to be present.Leaf disks were incubated with radioactive indoleacetic acid (as —C14OOK) and the radioactivity released as C14O2was measured. The ability of the tissue to decarboxylate the indoleacetate (‘oxidase’ activity) increased sharply, sometimes to as much as 1000%, in the first 3 days after inoculation. With susceptible hosts, this increase was followed by an almost equally sharp decrease to less than 50% of the values for uninfected tissue. With infected, resistant tissue, the secondary decrease in ‘oxidase’ activity was delayed and less pronounced.The results are discussed and a working hypothesis suggested with respect to the relation between susceptibility or resistance and the auxin balance.

ISSN:0008-4026    

DOI:10.1139/b58-001

出版商:NRC Research Press    

年代:1958

数据来源: NRC

摘要:

The occurrence and distribution of dwarf bunt of winter wheat in Ontario since 1952 is noted. While the severity of the disease has not been great, indications are that it is present in most areas of the province where winter wheat is produced in quantity and thus is of concern particularly to growers of seed wheat.The germination ofT.contraversawas studied with a view to determining the prerequisites for infection, and the development of dwarf bunt. Chlamydospores incubated on water agar and on ordinary soil at controlled temperatures between 0° and 15 °C. germinated only after incubation for 3 to 4 weeks at relatively low temperature, and required almost 8 weeks to reach a maximum of over 50% of the spores germinated.The germination process to the end point of sporidium development was dependent on light and a temperature about 5 °C. for maximum development. A slightly acid soil reaction favored spore germination, but soil moisture was a more critical factor.In field tests, a correlation was also shown to exist between temperature, light, and soil moisture, and the severity of dwarf bunt infection resulting in winter wheat seeded on infested soil. In continuing tests, chlamydospores have survived 3 years on the surface of soil with very little loss of viability.

ISSN:0008-4026    

DOI:10.1139/b58-002

出版商:NRC Research Press    

年代:1958

数据来源: NRC

摘要:

Successive leaves isolated from the gametophore exhibit differences in the number of regenerates obtained per organ. Starting from the base, successive leaves show an increasing number of regenerates per leaf. This pattern is similar in leaves isolated from young and older gametophores, although the younger ones show a much greater absolute number of regenerates.No correlation exists between the number of cells per organ and the number of regenerates. Although the size of the wound surface plays an important part in the number of regenerates produced, this factor cannot determine the regenerative pattern between successive leaves.Correlative factors are shown to exist in individual leaves and the distribution of regeneration in the leaf is determined also by these factors.It is concluded that the age of the organ determines the regular pattern of protonematal regeneration of successive organs.

ISSN:0008-4026    

DOI:10.1139/b58-003

出版商:NRC Research Press    

年代:1958

数据来源: NRC

摘要:

The genetics of self- and cross-incompatibility was studied in 12 related families ofLesquerella densipilaand in three families of theF1hybridL.densipila×L.lescurii. Silique swelling was used as the criterion for compatibility. Incompatibility results from the failure of pollen tubes to penetrate the stigmatic surface. Incompatibility inLesquerellais controlled by a series of multipleS-alleles at one locus. The pollen phenotype is determined sporophytically. A minimum of eightS-alleles was obtained fromL.densipila, and two fromL.lescurii. Two sorts of gene interaction, independence and dominance, were found among the fully analyzed heterozygotes. Dominance was restricted to the pollen controlling part of the alleles and two levels of potency were established.

ISSN:0008-4026    

DOI:10.1139/b58-004

出版商:NRC Research Press    

年代:1958

数据来源: NRC

摘要:

A study has been made of the effects of varying the pH value of the culture media on sucrose inversion and absorption, on respiration, and on growth ofFusarium moniliformeSheldon. The study was carried out on 1-week-old fungal mats that were then subjected to experimentation for 48 hours. Sucrose inversion was almost unaffected by pH values higher than 5.4 but was inhibited at pH 4.0. Sugar uptake was influenced more by lowering than by raising pH beyond 5.4. Carbon dioxide output per unit dry weight of mycelial mat was lowest at the pH optimum for growth, as measured by mat dry weight. At the same optimum pH there was also the highest rate of sucrose inversion and uptake. It seemed, therefore, that the effect of pH on growth was the additive effects on the different enzymatic processes operating in the metabolism of the fungus. It is also suggested that the external pH of the medium might act by the invasion of hydrogen or hydroxyl ions into the mycelial cells, thus changing the internal pH.

ISSN:0008-4026    

DOI:10.1139/b58-005

出版商:NRC Research Press    

年代:1958

数据来源: NRC

摘要:

Ovules within each ovary of self-fertileLotusspecies develop uniformly while those within each ovary of self-sterile species vary considerably in rate of development. All ovules in self-fertile species may be fertilized while less than one-half of those in self-sterile species are generally fertilized. Time of pollination is determined by the time when the stigmatic membrane ruptures in self-fertile species, by the time of rupturing by pollinating insects in self-sterile species. Higher numbers of ovules per ovary compensate for the proportion not fertilized in self-sterile species. The relationships of self-sterility to self-incompatibility in this genus, the evolution of this mechanism, and evidence that similar mechanisms are found in other legumes are discussed.

ISSN:0008-4026    

DOI:10.1139/b58-006

出版商:NRC Research Press    

年代:1958

数据来源: NRC

摘要:

Detached tobacco leaves were placed on solutions of uniformly C14-labelled glucose, "dextrins", and "oligosaccharides" which had been obtained by amylolysis of C14-starch with ptyalin. All three carbohydrates were absorbed by the leaves, and their subsequent metabolism was found to be essentially the same. This observation eliminates the earlier suggestion that the absence of free maltose during the breakdown of starch in tobacco leaves is due to the fact that its precursors are exceptionally active and are metabolized away before they have a chance to give rise to free maltose.

ISSN:0008-4026    

DOI:10.1139/b58-007

出版商:NRC Research Press    

年代:1958

数据来源: NRC

摘要:

Analyses of halophytic vegetation and saline soils adjacent to three different-aged impoundments were conducted on a study area in southeastern Alberta. Two impoundments had been constructed by Ducks Unlimited (Canada), and were 4 and 8 years old. The third was a small natural lake. Mesic prairie vegetation and soils were also sampled to secure comparative data. The establishment of artificial impoundments has raised the water table, permitting a rapid upward movement of soluble salts into the surface soils from lower levels in the glacial drift. Four distinct halophytic communities were recognized: aHordeumcommunity around all three impoundments, aDistichliscommunity around the older two, andSuaeda–ChenopodiumandSalicorniacommunities around the oldest (the natural lake). It is believed that as salt concentrations increase the mesic prairie community is replaced by aHordeumcommunity which in turn is replaced by aDistichliscommunity. Evidence ofSuaeda–ChenopodiumandSalicorniacommunities supplanting theDistichliscommunity is not clear cut and edaphic factors other than salinity per se are involved.

ISSN:0008-4026    

DOI:10.1139/b58-008

出版商:NRC Research Press    

年代:1958

数据来源: NRC

摘要:

A rapid blueing, indicating the presence of an extracellular oxidase, occurs when an alcoholic solution of gum guaiac is applied directly to cultures of wood-inhabiting Hymenomycetes that are associated with white rots while no color change follows its application to cultures of species that cause brown rots. Parallel tests on 133 species with the gum guaiac solution and the standard Bavendamm method, in which cultures are grown on malt agar containing gallic or tannic acid, gave identical results for nearly 90% of the species. Hence the rapid alcoholic gum guaiac method is recommended for determining extracellular oxidase production where this characteristic is used as a basis for separation in the identification of fungus cultures.

ISSN:0008-4026    

DOI:10.1139/b58-009

出版商:NRC Research Press    

年代:1958

数据来源: NRC

摘要:

×ElymordeumLepage is a validly published name for hybrids ofElymusL. ×HordeumL.; ×Hordelymusshould not be used as a name for these hybrids. Eight ×Elymordeumhybrids are listed in this paper: ×Elymordeum dutillyanumLepage (Elymus mollissubsp.mollis×Hordeum jubatum); ×Elymordeumschaackianumhybr. nov. (Elymus hirsutus×Hordeum brachyantherum); ×Elymordeumpiperihybr. nov. (Hordeum jubatum×Elymus triticoides); ×Elymordeumdakotensehybr. nov. (Hordeum jubatum×Elymus canadensis); !×Elymordeumtriploideumhybr. nov. (2n = 21) (Hordeum distichon×Elymus racemosusvar.racemosus); !×Elymordeumstebbinsianumhybr. nov. (Hordeum brachyantherum×Elymus glaucus); !×Elymordeumberkeleyanumhybr. nov. (Hordeum brachyantherum×Elymus condensatus); and !×Elymordeummontanense(Scribn. in Beal) comb. nov. (Elymus virginicus×Hordeum jubatum). Most specimens of !×Elymordeum montanenseare nm.montanense; two specimens with pubescent lemma backs are nm.pubescensnm. nov. The parentages of the four hybrids designated by !× have been experimentally confirmed.Most of the parental species ofElymusandHordeumwere tetraploid (2n = 28); the exception was the diploid, (2n = 14),Hordeum distichon. One artificial hybrid, !×E.triploideum, was from Russia; the other hybrids were natural or artificial hybrids from North America. Seven of the parental species ofElymusandHordeumare native in North America; two occur in Northeastern Asia and North America, one is native in Central Asia and one parent is a cultivated barley. In natural and artificialF1×Elymordeumhybrids, the anthers did not dehisce, the pollen was completely bad, and the spikes never set seed.The natural hybrids of !×Elymordeum montanenseoccur rarely and sporadically from Montana to Nova Scotia. An artificialF1hybrid was produced in 1954–55 from the cross,Elymus virginicusL. f.virginicus×Hordeum jubatumL. var.jubatum. The artificial hybrid was identical with the natural hybrid from Lower Onslow, Nova Scotia. The hybrids and parental plants were tetraploid, 2n = 28, and there were many meiotic irregularities in the pollen mother cells.

ISSN:0008-4026    

DOI:10.1139/b58-010

出版商:NRC Research Press    

年代:1958

数据来源: NRC