摘要:

The fungusConiochaeta velutina(Fuckel) Munk., which inhabits defective xylem in maple trees, has been developed for a joint genetical and plant pathological program. This paper describes progress made in the genetical aspect of the problem. From the more than 80 mutants forms which have been isolated after ultraviolet irradiation, 34 have been analyzed genetically by random spore analysis. Many of the mutant strains were incapable of acting as protoperithecial parents in crosses, thus limiting the number of crosses which could be made. Three linkage groups have been discovered, but many of the genes investigated showed no linkage with any other. This finding is in keeping with similar genetic analyses with other fungi.Linkage between the two pyrimidine-requiring mutants inConiochaetaparallels a similar finding inNeurospora.

ISSN:0008-4026    

DOI:10.1139/b69-145

出版商:NRC Research Press    

年代:1969

数据来源: NRC

摘要:

Aeciospore release was studied inGymnosporangium clavipesCke. & Pk.,G. globosumFarl., andG. juniperi-virginianaeSchw. under natural and controlled conditions. In nature diurnal periodicity occurred in all species with spores released in the morning as humidity dropped. Precipitation caused immediate release inG. clavipesandG. globosumbut prevented release inG. juniperi-virginianaebecause of the hygroscopic peridia. Under constant conditions of 70 °F, 90% R.H., photoperiod 12 hours beginning at 8 A.M., spore release inG. clavipesandG. globosumappeared to be continuous. InG. juniperi-virginianaeunder the same conditions there were twin peaks, a major one between 8 and 10 A.M. and a smaller one at 8–10 P.M. With a dew cycle inserted for 4–12 hours,G. clavipesandG. globosumreleased spores during the dew period but the hygroscopic peridia ofG. juniperi-virginianaeclosed the opening, preventing aeciospore release. Upon return to 90% R.H., spore release inG. clavipesandG. globosumdeclined for 3–9 hours, then returned to a steady level butG. juniperi-virginianaereleased great numbers of spores 2–4 hours after the dew period, because of the action of the peridial strands. In all species, fresh dry spores are shrunken and irregular, expanding immediately in contact with free water, shrinking as water is lost. Spore release is correlated with free moisture inG. clavipesandG. globosumand in all species with rapidly declining humidities.

ISSN:0008-4026    

DOI:10.1139/b69-146

出版商:NRC Research Press    

年代:1969

数据来源: NRC

摘要:

Seasonal and diurnal expansion and contraction of growing fruits ofAcer rubrumL.,Prunus serotinaEhrb.,P. pensylvanicaL.,P. virginianaL.,Quercus rubraL., andCorylus cornutaMarsh, var.cornutawere measured with modified Fritts dendrographs during the summers of 1966 and 1967. Throughout much of the summer the fruits exhibited recurrent shrinkage during the day and expansion at night. Fruit diameter fluctuations in 1967 were related to changes in vapor pressure deficit. Expansion of fruits generally occurred when vapor pressure deficit was decreasing or low and contraction resulted when vapor pressure deficit was increasing or high.

ISSN:0008-4026    

DOI:10.1139/b69-147

出版商:NRC Research Press    

年代:1969

数据来源: NRC

摘要:

Lateral bud initiation as determined by increased succinic dehydrogenase activity in the axils of certain leaves occurs by April 1 in the Victoria area. The number of lateral buds initiated did not vary significantly in 1967 and 1968 while the number of buds which developed did. Not all primordia which are initiated develop. Some abort very early and disappear completely while others develop bud scales then cease development and become latent. The rest of the primordia fully develop as vegetative, male, or female buds. In 1967 when abundant cones developed, 56% of the primordia fully developed and most of these became reproductive buds. In 1968 when no cones developed, only 31% of the primordia fully developed and all of these became vegetative. The number of cones produced was, therefore, not determined directly by the number of primordia initiated but by the proportion of primordia which developed as reproductive buds. The presence of abundant maturing cones on shoots formed the previous year greatly reduces the number of primordia which develop and, also, reduces the possibility of these becoming reproductive buds. Previous vegetative growth and cone crops affect the cone productivity in subsequent years and help explain the cyclic pattern of reproduction in Douglas fir.

ISSN:0008-4026    

DOI:10.1139/b69-148

出版商:NRC Research Press    

年代:1969

数据来源: NRC

摘要:

The level of certain enzymes was compared in albino, etiolated, and normal corn leaves. It was found that malic dehydrogenase and peroxidase were highest in light-grown albinos. Ribulose-1,5-diphosphate carboxylase, considered a chloroplast enzyme, was present in increasing amounts in the order albino < etiolated green < green. The level of this enzyme corresponded to the degree of chloroplast ultrastructure as determined by electron microscopic examination and insoluble protein. Only light-grown normal leaves had high catalase activity. All plants responded to light by an increased level of soluble protein, but only normal (i.e. non-albino) leaves showed an increase in insoluble protein. At least part of the higher soluble protein level could be accounted for by an electrophoretically distinct protein found only in light-grown plants.

ISSN:0008-4026    

DOI:10.1139/b69-149

出版商:NRC Research Press    

年代:1969

数据来源: NRC

摘要:

Pleocryptosporan. gen. (type,Pleocryptospora bambusae(Speg.) n. comb.), andVleugelian. gen. (type,Vleugelia betulina(Bubak & Vleugel) n. comb.) are described as members of the order Sphaeriales.Pseudocryptosporellan. gen. (type,Pseudocryptosporella polylepidis(Müller) n. comb.) is described as a member of the family Diaporthaceae, order Sphaeriales, andEudothia eugeniae(Nutman & Roberts) n. comb. (≡Cryptosporella eugeniaeNutman & Roberts) is proposed.

ISSN:0008-4026    

DOI:10.1139/b69-150

出版商:NRC Research Press    

年代:1969

数据来源: NRC

摘要:

Thirty-two ninhydrin-positive nitrogenous compounds were present in the xylem sap of 6- to 9-year- old American elms. Twenty-six of these compounds were identified. Total concentration of nitrogenous materials was several times higher in diseased than in healthy sap after inoculation during the susceptible period in the spring, but was lower after inoculations during the late resistant period. Percentage compositions of γ-amino-n-butyric acid, proline, and alanine in diseased sap increased after both spring and mid-summer inoculations. Proline, which was present in trace amounts in healthy sap, constituted 14 to 38% of the total in diseased sap. Percentage concentrations of amide nitrogen in diseased sap were reduced 50% or more in all inoculated trees. Percentages of ammonia, aspartic acid, glutamic acid, and several other amino acids did not change.

ISSN:0008-4026    

DOI:10.1139/b69-151

出版商:NRC Research Press    

年代:1969

数据来源: NRC

摘要:

Floral apices at the stages of sepals, petals, stamens, upright carpels, and elevated carpels were bisected by microscalpels, and the regeneration of the meristem halves, their grafting together, and the production of new appendages were studied. At the sepal stage the two halves regenerated into twin flowers, producing petals, stamens, and carpels above the cut surfaces which grafted together. Cusick's finding that, for a particular organ to be formed alongside a wound, the incision must be made before organs of this kind have appeared in their normal positions, was supported. At the stage of petals, however, the twin flowers produced petals as the first new appendages above the cut surfaces. At the stage of stamens, the first appendages produced above the cut surfaces were carpels, again supporting Cusick. Sometimes the new carpels so formed constituted separate adjacent whorls on the twin flowers. At both stages of carpels, the rest of the floral apex (receptacle) showed no regeneration except rapidly grafting together. The reunited receptacle was then used as in normal ontogeny, in formation of carpel margins on which ovules would later have been borne. Generally, cells beneath wound surfaces showed few divisions, compared with the vigorous responses of bisected shoot apices of other plants. Grafting, which did not occur in the terminal regions of bisected shoot apices, readily occurred at cut surfaces of halved floral apices, and this latter response became progressively more rapid in later stages of floral ontogeny. This grafting, along with progressive loss of potential for production of new lateral appendages, are interpreted as manifestations of aging in this determinate meristem, and support the hypothesis that differentiation is concomitant with loss in capacity for growth.

ISSN:0008-4026    

DOI:10.1139/b69-152

出版商:NRC Research Press    

年代:1969

数据来源: NRC

摘要:

The whiplash flagellum of zoospores ofPhytophthora palmivorabears fine lateral hairs 500 mμ long and 15 mμ wide. The lateral hairs on the tinsel flagellum of this species were similar in length, structure, and distribution to those in some other species ofPhytophthora. Glutaraldehyde fixation of the zoospores is superior to osmic acid fixation for the preservation of flagellar hairs.

ISSN:0008-4026    

DOI:10.1139/b69-153

出版商:NRC Research Press    

年代:1969

数据来源: NRC

摘要:

A Scots pine clone bearing cone clusters transmitted precocity to a portion of its progeny resulting from crosses to clones having normal cone distribution. Inheritance appeared to be governed by a single major gene whose expression was dominant or recessive depending upon which clone it was mated to. Differences of reciprocal crosses indicated maternal or cytoplasmic influence. This genetic variation in precocity can be used to reduce the generation interval, thereby facilitating genetic studies and breeding programs. Seed yield per pollination bag was several times greater for cone clusters than for normally distributed cones although viable seed per cone was 20% less. This can reduce the cost of producing hybrid seed if artificial pollination is required.

ISSN:0008-4026    

DOI:10.1139/b69-154

出版商:NRC Research Press    

年代:1969

数据来源: NRC