bluuebunny/crossref_metadata_2025 huggingface dataset:
In vitro germination of Entomophthora egressa resting spores
Authors: Nolan Richard A. , Dunphy Gary B. , MacLeod Donald M.
Published: September 2008

The resting spores of Entomophthora egressa MacLeod and Tyrrell germinated to produce a single germ tube, which in turn, produced a solitary, terminal germ conidium. The level of resting spore germination obtained in shaken, liquid, steam-sterilized media after 12 h of incubation at pH 7.5 was 93%. The effect of pH on resting spore germination in filter-sterilized media was investigated; in the range pH 4.5 to 9.5, pH 8.5 and 9.5 were optimal (100% germination after 96 h). No germination occurred at pH 4.5 to 6.5 before 96 h. At values greater than pH 6.5, the proportion of resting spores which germinated to form a single germ tube with a solitary germ conidium decreased, and the resting spores increasingly germinated by forming one to five hyphae. At high pH values (pH 7.5 to 9.5) septa occurred in the hyphae after 120 h of incubation. This latter phenomenon may have been correlated with the occurrence of hyphal bodies in shaken media at high pH (pH 8.5). The germination of resting spores to form hyphae at high pH levels may indicate the presence of a mechanism for infection via the gut.
Floral development of Najas flexilis
Authors: Posluszny U. , Sattler R.
Published: September 2008

Two subopposite leaves form at a node. The lower one arises almost simultaneously with the axillary meristem which it subtends. The upper leaf initiates after the lower one and does not subtend any structure. The axillary meristem gives rise to a renewal growth apex and a floral bud almost at its inception. In some cases the axillary meristem forms only a floral bud. The floral bud may be either staminate or pistillate. The main axis and the renewal growth in the axil of the lower leaf repeat this pattern of development. Staminate and pistillate flowers are almost indistinguishable at inception. They form as dome-like protuberances and both initiate girdling primordia, which become lobed at or immediately after inception. In the staminate flower the girdling primordium becomes the outer envelope, while a second girdling primordium formed acropetally becomes the inner envelope. Both envelopes overgrow the one-celled anther, which is the transformed staminate floral apex. In the pistillate flower the girdling primordium becomes the gynoecial wall that encloses the single bitegmic ovule, which is the transformed pistillate floral apex. On a short style a stigma with two to four branches develops. The renewal growth apices have a one-layered tunica. The two subopposite leaves are initiated through cell division in both tunica and corpus cells. The axillary meristem arises through periclinal divisions in the corpus cells. The girdling primordia of both staminate and pistillate floral buds are epidermal in origin as are the integuments of the ovule. Procambial development is acropetal following closely primordia inception. Each leaf, floral bud, and renewal growth apex receives a single strand. No vascularization is seen in envelopes of the staminate flower or the gynoecial wall of the pistillate flower, all of which remain two cell layers thick even at maturity.
Isolation and partial characterization of cytoplasmic and wall-bound acid phosphatases from wheat roots
Authors: Hasegawa Yoichi , Lynn K. R. , Brockbank W. James
Published: September 2008

In wheat (Triticum aestivum) roots, about 67% of the total activity of acid phosphatase was associated with the cell wall debris, and 35% of it was released from the wall by incubation with 0.8 M NaCl overnight. Three major cytoplasmic and two major wall-bound acid phosphatases were then separated by gel filtration on Sephadex G-75 and ion-exchange chromatography on carboxymethyl cellulose, and some of their characteristics were compared. They showed maximum activities in the same pH range (4.7–5.0) and had broad substrate specificities. They all showed high activity toward ADP. followed by ATP, glucose-6-phosphate, and creatine phosphate and much less activity toward AMP, glucose-1-phosphate, fructose-1,6-diphosphate, and ribose-5-phosphate. The wall-bound enzymes were more active to ADP and ATP than those of the cytoplasm. Mg2+, Ni2+, NaCN, and EDTA had no appreciable effects on the enzymatic activities. However, all enzymes were strongly inhibited by Hg2+ and Fe3+ and, to varied degrees, by Cu2+, Zn2+, Co2+, NaF. p-chloromercuribenzoate, and urea in that order. The molecular weights, estimated by sodium dodecylsulfate gel electrophoresis, ranged from 28 000 to 64 000.
Transmission characteristics and host range of the clover yellow edge agent
Authors: Chiykowski L.N.
Published: September 2008

A disease of clover, designated as clover yellow edge (CYE), was transmitted by Aphrodes bicinctus (Schrank) but not by the leafhoppers Scaphytopius acutus (Say), Macrosteles fascifrons (Stal), Agallia constricta Van Duzee, and Agallia quadripunctata Prov. or a Cercopid sp. Transmission by A. bicinctus, given various acquisition access periods on infected clover as nymphs, increased from 29% for 1 day to 67% for 14 days for females and from 42% for 1 day to 72% for 14 days for males. When leafhoppers were given similar acquisition access periods as adults, transmission ranged from 5% for 1 day to 24% for 14 days for females and from 25% for 1 day to 33% for 14 days for males. Inoculative female leafhoppers, given inoculation access periods ranging from 0.5 h to 96 h, began transmitting with 1-h feeds (29%) and reached a maximum with 96-h feeds (88%). Inoculative males began transmitting with 8-h feeds (50%) and reached a maximum with 48-h feeds (83%), the longest time tested. The average preinfective period for female and male leafhoppers tested individually was 42.2 days and 40.1 days, respectively. Once an insect became inoculative, it continued to transmit until death.Of the 31 plant species in 12 families tested as hosts of the clover yellow edge agent (CYEA). 15 species in 6 families developed symptoms. The most commonly observed symptoms were chlorosis or yellowing of leaf margins and reduction in the size of flowers and leaves. Aphrodes bicinctus transmitted CYEA to clover from eight of eight infected plant species tested as source hosts.
Achene production, dispersal, seed germination, and seedling establishment of Hieracium aurantiacum in an abandoned field community
Authors: Stergios Basil G.
Published: September 2008

Achene dispersal, seed germination, and seedling establishment of Hieracium aurantiacum L. were studied in an 18-year-old abandoned field community. Sexual reproductive output from selected patches declined rapidly after anthesis early in the season. The decrease in the number of achenes produced per head indicated a decline in reproductive output as the season progressed. Most of the achenes collected were deposited within 1 m of the source path. Achenes deposited near the source were larger and had a higher percentage viability than those deposited up to 3 m from the source. Seedling survival was higher within the parent patch compared with that at 5 dm in the adjacent herbaceous vegetation. Germination of the seeds gathered earlier in the season was higher than that of seeds gathered at monthly intervals as the season progressed. Cold treatment enhanced germination of seed produced late in the season but had little effect on seed produced early in the season.
Axenic culture of Puccinia species collected in Canada
Authors: Green G. J.
Published: September 2008

Twenty-eight of 29 cultures of Puccinia graminis tritici, 2 of P. graminis avenae. 1 of P. graminis secalis, 2 of P. coronata avenue, and 2 of P. recondita that originated in Canada grew on peptone medium. Three of the 36 strains investigated grew when subcultured. One grew for three subculturings, another grew for 1 year when subcultured at 2- to 4-week intervals, and a third ‘vegetative’ culture has produced fluffy, white mycelial colonies through numerous subculturings over 2½ years. The ‘vegetative’ culture was pathogenic at first but later appeared to become nonpathogenic. Uredial cultures established from it varied in urediospore color and virulence. Electron microscope studies showed that the culture is dikaryotic and apparently haploid.
Effects of osmotic potential on germination of microsclerotia and growth of colonies of Verticillium dahliae
Authors: Congly Huynh , Hall Robert
Published: September 2008

The influence of available water, expressed as osmotic potential (ψs), on germination of microsclerotia (MS) and expansion of colonies of Verticillium dahliae was studied in osmotically adjusted aqueous and agar media. In distilled water (ψs = 0 bar) at 25 °C, 64–70% of MS germinated within 36 h and the mean number of germ tubes per germinated MS (germination vigour) was 4.7. In aqueous solutions of KCl or NaCl percentage germination and germination vigour were increasingly inhibited as ψs was lowered, reaching 50% inhibition at −11 to −14 bar and 100% inhibition at < −98 bar. In aqueous sucrose solutions germination percentage and vigour were significantly higher (P = 0.05) than in salt solutions; maximum activity occurred at −4 bar, 50% inhibition occurred at −40 bar, and 100% inhibition occurred at < −114 bar. On corn meal dextrose agar (CMDA) amended with KCl, percentage germination at 25 °C was maximal at −9 bar, was reduced 50% at −40 bar, and was 0 at −90 bar. For a given ψs, germination percentages at 25 and 30 °C were significantly greater than at 20 and 15 °C. No germination occurred at 4 or 35 °C. Where ψs was adjusted with KCl, agar media were less inhibitory to germination than aqueous media between 0 and −50 bar. On CMDA media amended with KCl, colony expansion was progressively faster as ψs was lowered from −1.1 to −13 bar, then progressively slower as ψs was lowered further. Rates of colony expansion at 20 and 25 °C were significantly greater than at 4, 15 and 30 °C. At 25 °C growth was reduced 50% at −49 bar and was completely suppressed at −119 bar.
The characterization of a virus responsible for peach rosette mosaic and grape decline in Michigan
Authors: Dias Humberto F. , Cation Donald
Published: September 2008

Virus isolates obtained from peach with rosette mosaic and from grapes with ‘decline’ in Michigan have a similar host range and in vitro properties and morphology and are related serologically. Particles are isometrics averaging 28 nm in diameter. Isolates of virus from both sources, where transmitted manually, induced rosette mosaic on peach and decline on grapes.The virus is seed-borne in Chenopodium quinoa Willd., but it is not transmitted by Cuscuta campestris L. or by Myzus persicae Sulz. Partially purified virus preparations contain two infectious and serologically active components with sedimentation coefficients (s20,w) of 115 and 134, with molecular weight of 5.5 and 6.3 daltons, and with estimated values of 37 and 44% ribonucleic acid (RNA), respectively. The UV absorption at 254 nm of the middle and bottom infectious components is not dependent on the time after inoculation of C. quinoa, suggesting that the slowest component is not a precursor of the virus. Both components were reproduced when each was inoculated separately into C. quinoa. Virus isolates recovered from infected grapes varied in virulence, and serological differences could be detected by cross absorption and immunodiffusion tests. The name peach rosette mosaic virus (PRMV) is proposed for the virus responsible for the grape decline. The cryptogram of the virus is(R)/*;*/*;S/S;S/Ne.
Hormonal effect on polyphenol accumulation in Cassia tissues cultured in vitro
Authors: Shah R. R. , Subbaiah K. V. , Mehta A. R.
Published: September 2008

Effects of auxin and kinetin on growth and production of phenolic compounds in cultured Cassia fistula L. tissues were examined. Initiation of polyphenols was largely determined by the auxin concentration in the medium. Growth of the cells in relation to accumulation of polyphenols was studied at different auxin and kinetin concentrations. The accumulation of phenolic materials was essentially restricted to the most rapid phase of the growth cycle.Progressive changes in the pattern of peroxidase activity were followed and their relationship with polyphenol synthesis is examined.
Photosynthetic changes in Fusarium-infected cotton
Authors: Krishnamani M. R. S. , Lakshmanan M.
Published: September 2008

Resistant and susceptible cotton cultivars when infected with Fusarium vasinfectum showed a reduced rate of photosynthesis as determined by O2 evolution and 14CO2 fixation by their leaf tissues. The infected leaves exhibited a lower starch content and a slight, but consistent, reduction in total chlorophyll and chlorophyll b. There was no direct correlation between loss of chlorophyll and the low rate of photosynthesis. Chlorophyllase activity was enhanced in the infected leaves. Fusaric acid reduced the rate of photosynthesis of cotton cultivars slightly, whereas crude and dialysed culture filtrates brought about marked reduction in photosynthetic rates. The possible role of a hitherto unidentified toxin in wilt pathogenesis is suggested.
Growth of plant cell (Ipomoea) suspension cultures at controlled pH levels
Authors: Martin S. M. , Rose Dyson
Published: September 2008

Suspension cultures of a plant cell line initiated from Ipomoea sp. root tissue were grown in defined medium at controlled pH levels of 4.8, 5.6, 6.4, and 7.1 with ammonium and nitrate as the nitrogen sources. Biomass yield was less at pH 4.8 and 7.1 than at the intermediate pH levels. At pH 7.1, this resulted from the inability of the culture to utilize nitrate. At pH 4.8, the cause of the low yield was not apparent but was probably related to a less efficient utilization of sucrose.The ability of the cells to utilize ammonium increased with increasing pH, with a possible maximum at pH 6.4. The ability to utilize nitrate decreased with increasing pH and was essentially zero at pH 7.1. At pH 4.8, ammonium was released into the medium during part of the growth cycle, indicating that the rate of nitrate reduction exceeded the rate of incorporation of the ammonium thus formed.Utilization of nitrate was not inhibited by the presence of ammonium.
Further analysis of the moving strand model of translocation, using a numerical calculation
Authors: Ferrier Jack M. , Tyree Melvin T.
Published: September 2008

Numerical computer results for the moving strand model of phloem translocation are in excellent agreement with the analytical results of Canny and Phillips. Numerical results are presented for the case of constant loading of radioactive sugar, for which Canny and Phillips failed to specify the appropriate boundary condition. Numerical results are obtained for a pulse time variation of loading and for a pulse time variation of sugar in the loading region reservoir, cases which were not solved by Canny and Phillips, and the results are compared with experimental data. We show that the moving strand model does not predict the kind of moving pulse of tracer observed in morning glory (Fisher 1975) after pulse labeling a source leaf with 14CO2 except when transport parameters are specified that clearly conflict with those measured and proposed by Canny. We see little theoretical justification for retaining the moving strand model.
Systematics of Conidiobolus (Entomophthorales) using numerical taxonomy. II. Taxonomic considerations
Authors: King Douglas S.
Published: September 2008

The genus Conidiobolus is described and separated from Entomophthora by primary conidia and zygospore characters and ease of culturability. Based on the cluster analysis presented in part I of this series, 26 species are recognized. One additional species is recognized. For the 26 species separated in the cluster analysis, a key and list of synonyms are provided. Four unnamed isolates may represent additional species.
Pure culture synthesis of bearberry mycorrhizae
Authors: Zak B.
Published: September 2008

Synthesis of bearberry (Arctostaphylos uva-ursi) ectendomycorrhizae in pure culture by Hebeloma crustuliniforme, Laccaria laccata, Lactarius sanguifluus, Pisolithus tinctorius, Poria terrestris vars. cyaneus and subluteus, Rhizopogon vinicolor, and Thelophora terrestris is described.
Fungi associated with small wheat bulks during prolonged storage in Manitoba
Authors: Wallace H. A. H. , Sinha R. N. , Mills J. T.
Published: September 2008

Two bulks of wheat of 13.5 metric tons with an initial 13.5% moisture content were used to determine the microbial factors governing long-term spoilage of wheat. During 5 years, data for moisture, temperature, seed viability, and fungi were collected at monthly intervals at different depths and locations. During summer, moisture accumulated at the centre of the bins at 61 cm below the surface. At this time there was a 15 °C variation in temperature between the surface and bottom of the bulks. In autumn, loss of moisture occurred at all depths below the surface, but the temperature variation was small. After 3 years, grain at the centre at the 61-cm depth became infected by fungi; loss of seed viability occurred with no heating. A small damp pocket in a bin of dry grain caused a hot spot, but this had little subsequent effect on the rest of the grain. As the grain aged, seasonal changes in temperature and moisture caused an increase in Penicillium species each autumn and a decline of Alternaria alternata each spring and autumn.
Histology of Cochliobolus sativus infection in subcrown internodes of wheat and barley
Authors: Huang H. C. , Tinline R. D.
Published: September 2008

Histological study of the infection process of Cochliobolus sativus in subcrown internodes of postseedling plants failed to disclose differences in wheat and barley cultivars that differed markedly in resistance to common root rot in the field. Appressoria and infection cushions were formed on the host surface before penetration. The dome-shaped infection cushions consisted of short-celled hyphae surrounded by long-celled running hyphae. Penetration occurred by fine infection pegs produced from appressoria or the short-celled hyphae in the infection cushions. A lignituber occurred beneath each penetration site. The fungus penetrated wheat or barley subcrown internodes via various epidermal cells, including hair cells, stomatal guard cells, and the rectangular cells. Infection proceeded from the epidermis to the cortex and endodermis, resulting in breakdown of these tissues. Sometimes the stele also was invaded and vascular tissues were occluded. Three morphologically different hyphae, namely fine aseptate infection hyphae, long-celled running hyphae, and coarse, short-celled hyphae, were observed. Dark-stained objects, directly or indirectly associated with the fungus, frequently were found in infected tissues.
Salt stress responses in Lasthenia glabrata, a winter annual composite endemic to saline soils
Authors: Kingsbury Ralph W. , Radlow Anne , Mudie Peta J. , Rutherford John , Radlow Robert
Published: September 2008

Several populations of Lasthenia glabrata Lindl. were grown through a complete life cycle in a range of salinities and evaluated in terms of relative salt tolerance. Parameters included emergence, growth, flowering, chloride accumulation, yield, and studies on the breeding system. A second part of the study consisted of germinating the populations in tap water, then applying a 50% seawater treatment at different stages of development. Effects noted included an increase in flowering and a depression of height and yield. The overall response was considered an ecophysiological adaptation to salt stress at the species level and, secondarily, a function of the respective habitat salinity.
The genus Draba in Canada and Alaska: key and summary
Authors: Mulligan Gerald A.
Published: September 2008

A key is given to the 40 species of Draba present in Canada and Alaska. Chromosome numbers for 37 species, information on breeding systems, the extent of interspecific hybridization, and a summary of the geographical distribution of each species are also included.
Succession écologique des forêts d'épinette blanche et fluctuations climatiques, Poste-de-la-Baleine, Nouveau-Québec
Authors: Payette Serge
Published: September 2008

The stand structures of three white spruce (Picea glauca (Moench) Voss) climax forests of the hemiarctic zone in New Quebec are described. The forests have a similar structural pattern, characterized by important and irregular variations in the number of individuals per age, diameter, and height classes. These variations are synchronic and suggest that the climate strongly influences the forest regeneration. The discontinuous trend in the curves may possibly be related to changes in seed production and seedling establishment. Synchronism between the 300-year dendrochronological curve and the stand age-structure is apparent. The hollow parts of the age curves are related to unfavorable climatic periods and the peaks to favorable ones. These climatic fluctuations are probably responsible for either a decrease or an increase in white spruce seed production important to hemiarctic forest regeneration. Finally, the writer suggests a theoretical age-structure curve for climax forests in the maritime forest-tundra near Poste-de-la-Baleine, New Quebec.
Glycerol uptake by the haustorial mycoparasite Tieghemiomyces parasiticus in axenic culture
Authors: Binder F. L. , Pierce J. C.
Published: September 2008

Uptake of [14C]glycerol by 72-h-old resting cell suspensions of Tieghemiomyces parasiticus was linear with respect to time and had the characteristics of a protein-mediated system of transport. The uptake process obeyed Michaelis–Menten kinetics with an apparent Km of 8 × 10−4 M and Vmax of 5.26 nmol ∙ min−1 ∙ mg−1 dry wt. Glycerol uptake exhibited pH and temperature dependence with optima at pH 5 and 35 °C, respectively. The energy of activation (Ea) and Q10 for this uptake process were calculated to be 12 043 cal/mol and 1.98, respectively, between 20 and 30 °C. Glycerol uptake also exhibited substrate specificity and was inhibited by α-glycerolphosphate and 1,2-propanediol, while inhibition by 1,3-propanediol was negligible. Preexposing resting cell suspensions to sodium azide and 2,4-dinitrophenol (4 × 10−3 M) significantly inhibited glycerol uptake, possibly suggesting an energy requirement for transport. Cold osmotic shock treatment severely reduced glycerol uptake but did not destroy cell viability.
Induction of resting spore germination in Entomophthora aphidis by long-day light conditions
Authors: Wallace D. R. , MacLeod D. M. , Sullivan C. R. , Tyrrell D. , Lyzer A. J. De
Published: September 2008

A small proportion of Entomophthora aphidis Hoffmann resting spores produce germ tubes within a few days upon incubation at 20 °C with ample moisture in the dark without chemical treatment or exogenous nutrient. However, the germ tubes do not branch and germ conidia are not produced until after much longer incubation, and then only sparsely. Light periods of 14 h or more in a 24-h day greatly enhance the germination level but seldom result in germination of more than 50% of the spores. Branching of the germ tubes, germ conidia production, and germination of germ conidia all occur rapidly under long-day conditions. The principal germination interval is between 10 and 30 days under the conditions used and it was estimated that the germination level would stabilize after about 60 days. Variability in germination from plate to plate made with the same spore preparation was from about 25 to 50%.
Flax rust resistance involving the K gene: an ultrastructural survey
Authors: Coffey Michael D.
Published: September 2008

An electron microscopic study of major gene resistance involving the flax K gene and the rust fungus Melampsora lini revealed several interesting ultrastructural features. Up to 9 days after infection, most haustoria-containing resistant host cells appeared viable. During this period there was a progressive increase in a fibrillar deposit in the extrahaustorial matrix which was not detected in the susceptible host. This material was in direct continuity with the distal wall of the haustorial neck. It frequently constituted an apparently complete layer or 'encapsulation' around the haustorium and was present in 75% of the extrahaustorial matrices as early as 4 days after infection. Initially, callose-like encasements formed around only a small percentage of haustoria in the resistant host; however, by day 9, about 20% of the haustoria were encased. No encasements were found around susceptible haustoria at this stage. Hypersensitive host cell collapse occurred in a small percentage of resistant infections.
Occurrence of transfer cells in vascular parenchyma of Hieracium florentinum roots
Authors: Letvenuk Linda J. , Peterson R. L.
Published: September 2008

In the roots of Hieracium florentinum plants grown in hydroponic nutrient cultures, vascular parenchyma cells adjacent to both xylem and phloem conducting elements develop wall ingrowths and become transfer cells. Xylem transfer cells occur around the protoxylem elements and secondary xylem elements at the base of the junction of a lateral root with the main root stele and along the xylem elements of the lateral root for some distance into the lateral root. Phloem transfer cells occur adjacent to sieve elements in the phloem regions of the main root stele which have connections with the lateral root phloem and adjacent to sieve elements in the lateral root. Transfer cells were absent in the vascular parenchyma of the main root stele not associated with lateral roots.
Classification of Canadian oat cultivars by quantifying the size–shape of their 'seeds': a step towards automatic identification
Authors: Baum B. R. , Thompson B. K.
Published: September 2008

A series of quantitative measurements were obtained from the upper and lower seeds of various Canadian oat cultivars, the aim being to determine if such measurements could be used to discriminate among cultivars. Although the measurements were obtained manually, the system of measurement was developed with the view to automatic recording by scanning devices. The study involved 206 samples of 15 cultivars grown in Canada, taken from different provinces and from different breeding categories (foundation, select, registered, certified). The data consisted of about 90 thousand measurements. Two observers were used, though only some of the samples were processed by both. Comparisons between observers indicated the presence of a strong subjective influence in the measurements of one observer; the data from this observer were left out of subsequent analyses. There was evidence of substantial differences among the size–shapes of the cultivars, enough to suggest that most cultivars could be differentiated on the basis of these measurements alone. The results of the study reflect not only the potential of size–shape in identifying cultivars but also the importance of developing objective methods of obtaining the measurements. The differences in measurements between observers stress the need for accurate methods of data gathering. Because quantitative measurements of size–shape can be obtained readily by scanning devices, they may have considerable value in comprehensive schemes for cultivar identification or quality control.
Anatomical aspect of 2,4,5-T and dalapon toxic action on Norway spruce (Picea abies) seedlings
Authors: Tonecki Jan
Published: September 2008

The results are presented of investigations on the effect of 2,4,5-T (butyl ester of 2,4,5-trichlorophenoxy acetic acid) and dalapon (sodium salt of 2,2-dichloropropionic acid) on tracheid differentiation and mitotic divisions of vascular cambium and phellogen in 1- and 2-year-old shoots of spruce seedlings treated with herbicides in concentrations of 10, 100, 1000, 5000, and 50000 mg l−1 before and after bud differentiation.The investigations showed that 2,4,5-T at 100 and 1000 mg l−1 can periodically stimulate mitotic activity of the cambium, resulting in an increase of tracheid number. Increased mitotic activity of phellogen, which resulted in an increase in number and expansion of cortical and peridermal cells, caused by 2,4,5-T, was also observed. Dosages of 5000 mg l−1 and higher of 2,4,5-T supressed mitotic divisions.No stimulatory effects of dalapon, applied on seedlings either before or after bud differentiation, were observed either in the cambium or in the cortex and the periderm. High dalapon concentrations (over 5000 mg l−1) retarded mitotic divisions in the cambial zone.
Growth of races 38 and 17, Puccinia graminis f. sp. tritici, on artificial media
Authors: Bushnell W. R.
Published: September 2008

Isolates of races 38 and 17, Puccinia graminis f. sp. tritici, which had grown poorly in earlier trials on 0.1% peptone media, were grown successfully on media containing higher concentrations of peptone combined with an acid hydrolysate of casein. Race 38 grew consistently on media containing 0.4% peptone and 0.4–0.8% casein hydrolysate in a procedure in which 1–3 mg of uredospores were seeded on 15 ml agar medium in 85-mm-diam petri dishes. Race 17 grew less consistently than race 38 did, but its consistency was improved by reducing dish diameter to 43 mm and agar volume to 3 ml and increasing the inoculum mass to 5–10 mg/dish. Other modifications in procedure and in media composition failed to improve growth of race 17 from uredospores. In serial monthly subculturings, race 38 achieved stable growth rates (exceeding 40 μm increase in colony diameter per day) by the 2nd month after a culture had originated from spore seedings. Race 17 grew poorly in serial subculturings, except for one culture which began to grow well after a year of extremely slow growth. The results indicate that a wider range of isolates of P. graminis f. sp. tritici can be grown on enriched media than was possible earlier but that routine, rapid culture of some isolates is not yet possible.
Germination–lysis as a mechanism for biological control of Thielaviopsis basicola pathogenic on soybean
Authors: Sneh B. , Holdaway B. F. , Hooper G. R. , Lockwood J. L.
Published: September 2008

Amending soil with alfalfa hay or other dried, green plant residues stimulated chlamydospore germination of Thielaviopsis basicola. Within 3 to 6 days the germ tubes lysed resulting in the decline in viable chlamydospores and of disease severity of soybean seedlings planted in amended soil. When chlamydospores were added immediately after the amendment, maximum germination was recorded after 2 days. The number of spores with germ tubes declined to zero after 6 days as a result of lysis. Incubation of alfalfa in soil for 1 or more days before chlamydospores were added reduced or nullified the effect of the amendment. Water-soluble substances from alfalfa hay, including carbohydrates, amino acids, and organic acids, were more stimulatory and caused greater decline in chlamydospore population than ether or chloroform-methanol-soluble substances.
A method for separating the various forms of invertase in extracts of single leaves or plants of wheat
Authors: Roberts D. W. A.
Published: September 2008

A method for the separation and approximate quantitation of two of the forms of invertase (EC 3.2.1.26) from the leaves of single young wheat plants (Triticum aestivum L. emend Thell. ssp. vulgare) is described. Samples sufficiently large (125 mg fresh weight or more) for separation may be obtained without destruction of the plant so that it can later be grown to maturity. The method can be used to predict the behavior of large-scale separations using gel filtration on Sephadex.
Some physical and chemical properties of the lettuce seed endosperm
Authors: Speer Henry L. , Hsiao A. I.
Published: September 2008

Lettuce seeds (Lactuca sativa) are shown to be encased in an osmotically active cellulose membrane derived from the endosperm. The osmotic activity of this membrane is maintained in seeds treated with strong acid (4 M HCl), strong base (4.4 M NaOH), organic solvents, and protein solvents, indicating that there is no contribution of lipid, protein, or living cells to the osmotic properties of the membrane. Only cellulose solvents such as xanthate and cellulase were effective in disrupting the membrane.When dry seeds are treated with 50% solutions of methanol, ethanol, or acetone or with 10 mM HgCl2, they become osmotically distended seeds (ods) as a result of the accumulation of soluble molecules in the fluid layer (EEF) between the membrane and embryo. This process is temperature dependent and appears to require enzymatic activity.The molecular exclusion limit of the ods membrane was measured by osmotic equilibration techniques and was found to be about 300 daltons. This then explains previous observations on the impermeability of lettuce seeds to substances such as actinomycin D (mol. wt. 1255.5) during germination. Molecules of molecular weight greater than about 300 daltons will be excluded until the endospermal barrier is ruptured at about 10–12 h after germination onset.
Selection and characterization of cultured carrot and tobacco cells resistant to lysine, methionine, and proline analogs
Authors: Widholm Jack M.
Published: September 2008

Amino-acid-analog-resistant lines were selected from mutagen-treated suspension-cultured tobacco (Nicotiana tabacum L.) and carrot (Daucus carota L.) cells. Tobacco cell lines resistant to the lysine analogs aminoethyl-L-cysteine and delta-hydroxylysine and carrot lines resistant to a methionine analog and a proline analog, ethionine and hydroxyproline, respectively, were selected. The resistant lines were 10 to more than 1000 times less sensitive to the analogs than the parent strains. The resistant cells were selected with a low frequency, were generally stable during growth in the absence of the selective agent, and accumulated the corresponding natural free amino acid. The lysine-analog-resistant tobacco lines had more than 10 times the normal levels of free lysine while the methionine-analog-resistant carrot line had similar increases in free methionine. The hydroxyproline-resistant carrot line contained from 15 to 30 times the normal free proline levels and was cross resistant to certain other proline analogs.
Cell wall regeneration and colony formation from isolated single geranium protoplasts in microculture
Authors: El-Nil M. M. Abo , Hildebrandt A. C.
Published: September 2008

Geranium (Pelargonium hortorum Bailey) protoplasts were obtained from haploid callus tissue from anther cultures after 3 h of incubation with 2% cellulase (Onozuka SS) and 0.2% pectinase in Murashige and Skoog (MS) medium. The protoplasts were washed and incubated in conditioned MS medium supplemented with 0.1 M mannitol and 0.01 M sucrose in microcultures. The amount of cell wall material deposited on the surface of the living single protoplast was measured with the polarizing microscope and photovolt meter. The refracted light was measured as arbitrary units of photovolts every 12 h. The cell wall regeneration was detected after 24 h of incubation. Maximum deposition of cell wall cellulose material was achieved after 60 h and measured 18.4 photovolt units for cells with diameter of 20 to 40 microns (μ) and 22 photovolt units for cells with diameter of 41 to 60 μ. Mitotic cell divisions started in 12 out of 174 reconstituted cells at the 4th or 5th day of incubation. After nuclear division, new cell wall material deposited on both sides of the isotropic middle lamella. Cytokinesis was completed after 15 h. Twelve colonies, which stayed alive for 2 months, were produced from single protoplasts in microcultures. This is the first attempt to quantify the progressive cell wall material deposition on the surface of living plant protoplasts.
Gametangial meiosis in Phytophthora capsici
Authors: Sansome E.
Published: September 2008

The report of Stephenson et al. that the nuclear divisions in the gametangia of Phytophthora capsici are mitotic, resembling the divisions in the vegetative hyphae, was not confirmed. Pachytene, diplotene, and diakinesis stages were observed in the oogonia. Metaphase and anaphase were followed by a second division without any increase in nuclear and chromosome size between the two divisions. The haploid chromosome number is nine and an association of four chromosomes is present in one or both parents.The association of four chromosomes observed at diakinesis and metaphase is evidence that pairing of homologous parts occurs during the first division and is thus proof that the gametangial divisions are meiotic.There was no evidence of a prolonged prophase in the first division of the zygote nucleus and an eight-nucleate oospore showed no evidence of reduction in nuclear size or nuclear elimination such as would be required to account for the homokaryotic condition of single-oospore cultures on the hypothesis of zygotic meiosis.The problems involved in obtaining reliable chromosome counts from somatic nuclei are discussed.
Ultrastructure of cell division in Cladophora. Pregametangial cell division in the haploid generation of Cladophora flexuosa
Authors: Scott J. L. , Bullock K. W.
Published: September 2008

Cell division preceding gamete formation in the haploid generation of Cladophora flexuosa was studied with the electron microscope. Numerous, asynchronous mitotic nuclear divisions are concurrent with the progressive cleavage of the cytoplasm by invaginations of a central and peripheral vacuolar system. The spindle is enclosed by the nuclear envelope during all stages of mitosis and is associated with polar centriole pairs. The cytokinetic process is not associated with microtubules and is basically similar to that observed in other macroscopic, multinucleate green algae. Unusual mitochondria, characterized by specialized double-membrane-enclosed, presumptive DNA regions, were found during the later stages of reproductive differentiation. It is emphasized that the different types of cell divisions which can occur in plants possessing a haplodiplontic type of life history should all be thoroughly examined before the establishment of a particular mitotic sequence for any given species.
Studies on upper timberline: morphology and anatomy of Norway spruce (Picea abies) and stone pine (Pinus cembra) needles from various habitat conditions
Authors: Baig M. N. , Tranquillini W.
Published: September 2008

The importance of the anatomy of the needles of coniferous trees in determining alpine timberline was studied in the Austrian Alps. Samples of 1- and 2-year-old needles of Picea abies (L.) Karst. and Pinus cembra L. were made from wind-exposed and wind-protected timberline (2140 m above sea level (a.s.l.)), and from the kampfzone (2040 m a.s.l.), forestline (1940 m a.s.l.), and valley bottom (1000 m a.s.l.). The samples were measured for number of needles per centimetre twig, twig length, needle length, cuticle thickness, thickness of epidermis and hypodermis, and depth of stomatal crater. There is a decrease in cuticle thickness with increasing altitude and with increasing wind exposure at timberline, and this is correlated with increased transpiration. The role of inadequate cuticle formation in desiccation damage and mortality of the needles is a significant factor in the control of upper timberline.
Comparison of multivariate analyses using taxonomic data of Oxalis
Authors: Denton Melinda F. , Moral Roger del
Published: September 2008

Several multivariate techniques are used to analyze the resemblances between the 25 North American taxa of Oxalis section Ionoxalis. Results from each of three clustering strategies are subjected to stepwise discriminant analysis for refinement and reallocation. The resultant phenetic classifications are compared with each other and with a recent conventional treatment using the same data. Affinities of the taxa, along with new relationships indicated by these analyses, are discussed. A polythetic hierarchical clustering method using an information statistic produces the most efficient and reliable phenetic classification and is recommended for use in systematic studies.
The epidemiology of common root rot in Manitou wheat. IV. Appraisal of biomass and grain yield in naturally infected crops
Authors: Verma P. R. , Morrall R. A. A. , Tinline R. D.
Published: September 2008

The effects of common root rot (Cochliobolus sativus) on plant biomass and grain yield in naturally infected Triticum aestivum cultivar Manitou were studied at Matador, Saskatchewan, by sampling plants at intervals from seeding to maturity in 1969, 1970, and 1971. Plants were categorized according to the extent of subcrown internode lesions as clean, slight, moderate, or severe. Dry weights and grain yields of plants in each category were determined. Decreasing mean dry weight per plant at all dates and grain yield per plant were consistently associated with increasing disease severity. Significant differences in biomass and grain yield generally existed between clean and slight, slight and severe, and moderate and severe categories. Very close relationships existed between losses in biomass and grain yield both per plant and per unit area. Overall mean biomass losses at maturity in severe, moderate, and slight plants as compared with clean were 58%, 37%, and 25%, respectively; losses in grain yield were 59%, 38%, and 26%, respectively. Biomass losses per square metre increased steadily with time, in all treatments. Grain yield losses per square metre for 1969, 1970, and 1971 summer-fallow checks were 30, 35, and 30%, respectively; the biomass losses at the final sampling dates were analogous.
Studies on lichen-dominated systems. XVII. The colonization of young raised beaches in NW Ontario
Authors: Pierce W. G. , Kershaw K. A.
Published: September 2008

The colonization of young raised-beach ridges and the subsequent development of lichen–heath vegetation is described for the Hudson Bay coastal tundra. The sequence of development of lichen–heath was quantified both on a coastal intraridge sequence as well as an interridge, inland sequence of comparable age. Corresponding gradients of elevation, soil peat thickness and organic matter were found along the developmental sequence, but definite trends in soil pH and available nutrients are absent. Superimposed upon the distributions of major species along the developmental sequence are marked changes in abundance over the beach-ridge profiles which reflect the adaptations of species to environmental factors related to ridge microtopography.
Phragmidium ivesiae and its allies in North America
Authors: Savile D. B. O.
Published: September 2008

Detailed descriptions, host range, and geographic range are given for the widespread Phragmidium ivesiae and the rarer Ph. biloculare, Ph. boreale (Ph. ivesiae ssp. wyomingense), and Ph. horkeliae.
A partially computerized documentation system for microscopic soil fungi
Authors: Anderson Traute-Heidi , Bodenstein J. , Domsch K. H.
Published: September 2008

A computerized documentation system for compiling both a reference list and information on microscopic soil fungi is described. The system can be handled with a small computer. The programs are written in FORTRAN IV.
The fine structure of ascospore formation in Ceratocystis fimbriate
Authors: Stiers David L.
Published: September 2008

Ascospore formation in C. fimbriata Ell. & Halst. takes place in the eight-nucleate ascus. It is preceded by the appearance of discrete vesicles in the ascus which coalesce to form individual membrane fragments. These membrane fragments elongate to form long continuous strands of double membranes which become the ascospore-delimiting membranes. Ascospores are delimited in one of two ways within the ascus. In one way the strands of double membranes seem to form a sac around each of the nuclei, which eventually closes to form the ascospore. In the second method the strands of double membranes form a large ascus vesicle which encloses the eight nuclei and most of the ascus cytoplasm. The ascospores are then delimited by the formation of lobes on the ascus vesicle. Each of the newly delimited ascospores appears to be paired on one side with another ascospore. After spore delimitation is complete, the ascospore wall is laid down between the ascospore-delimiting membranes. After the walls are differentiated, a brim forms on each side of the flattened area of contact between the paired ascospores. On maturity the ascus breaks down and single, brimmed ascospores are released.
Plant succession on an active tundra mud slump, Garry Island, Mackenzie River Delta, Northwest Territories
Authors: Lambert J. D. H.
Published: September 2008

The vegetation in the latter stages of an active mud slump of known age on Garry Island, Mackenzie River Delta, N.W.T., is described using principal-component analysis. Three associations are recognized. Senecio congestus and isolated hummocks with dwarf shrub – heath vegetation dominate during the first 4 years after exposure. The Arctagrostis latifolia – Senecio congestus association that dominates after 4 years represents the second stage of development after the disappearance of recognizable hummocks. The Arctagrostis latifolia – Eriophorum scheuchzeri association that dominates after 6 years is the third stage in the revegetation sequence and represents further stabilization of the mud slump surface. The frequency of hummock-associated species is greatly reduced. The rapid rate of natural revegetation, in such a mud slump where the headwall had been receding, would suggest that man-induced reseeding programs, in all probability, would not speed up the process.
Buergenerula spartinae sp. nov., an Ascomycete from salt marsh cordgrass, Spartina alterniflora
Authors: Kohlmeyer J. , Gessner R. V.
Published: September 2008

Comparisons between the marine wood-inhabiting Ascomycete Sphaerulina pedicellata Johnson and a similar species from Spartina spp. demonstrate that the two fungi are not identical. The species from Spartina, described as Buergenerula spartinae sp. nov., is compared with the type species of the genus, B. biseptata (Rostrup) Sydow. Buergenerula spartinae is characterized by hyphopodia, periphyses, pseudoparaphyses, unitunicate, thick-walled asci with a non-amyloid, ring-like apical apparatus, and clavate, three-septate, hyaline ascospores. Sphaerulina pedicellata is considered a doubtful species.
Growth pattern and seasonal behavior of buds of Colliguaya odorifera, a shrub from the Chilean mediterranean vegetation
Authors: Hoffmann Alicia J. , Hoffmann Adriana E.
Published: September 2008

Colliguaya odorifera Mol., an euphorbian shrub, grows among the sclerophyllous scrub of central Chile. The growth pattern and seasonal behavior of the floral and vegetative buds are analyzed, with special reference to the climatic conditions (cool humid winters and dry hot summers). Observations were conducted on marked twigs and in sections of embedded material.The branching system is of a Y-shaped sympodial type. The growth season of C. odorifera extends from early winter to the beginning of summer. When the dry season starts, the vegetative apical meristem is converted into a floral bud, and in the leaf axils partly predetermined, unprotected vegetative buds develop. Both types of buds remain dormant during the drought period. Soon after the first winter rains begin, activity is resumed: the preformed flowers and leaf buds unfold and grow, and a few more leaf pairs develop during the current year. Thus, buds are influenced partially by the climate of the previous and of the next year.