摘要:

SUMMARYThe yearly incidence of root colonization and extramatrical spores of vesicular-arbuscular (-VA) mycorrhizal fungi were determined for six agronomic crops grown in monoculture for 7 yr on a newly cleared woodland site in northwest Florida. Thirteen species of VA-mycorrhizal fungi were identified from the test site from 1972 to 1978. Sorghum yielded the greatest number of species (12) from a single crop during this period. The highest number of spores was associated with soybean and the lowest number of spores was found in the native woodland. Spores ofGigaspora margarita, G. gregaria, andG. giganteawere most numerous from soil around soybeans whileGlomus fasciculatusandG. claruswere most numerous around roots of bahia grass.Acaulosporaspp. were most abundant from soil around cotton and peanut. The yearly incidence ofGigaspora margaritaspores increased whileG. gregariaandG. giganteadecreased in numbers during the 7-yr study.Glomus macrocarpusvar.geosporusandG. fasciculatuswere observed in 1971 and/or 1972 but were not recovered again until 1978. Only two species,Gigaspora margaritaandG. gregaria, were recovered each yr that samples were taken. The highest level of root colonization occurred in 1972 and was followed by a decline in 1973–1974, but mycorrhizae showed a general increase in 1975–1976. It is suggested that the observed changes in the incidence of VA-mycorrhizal fungi were primarily due to the agricultural system of monoculture.

ISSN:0027-5514    

DOI:10.1080/00275514.1980.12021206

出版商:Taylor&Francis    

年代:1980

数据来源: Taylor

摘要:

SUMMARYSoil moisture, temperature, and—to a lesser degree—pH influenced germination ofGlomus epigaeusspores, whereas levels of soil fertility and spore density had little or no effect. Maximum germination occurred in soil at moisture levels at or above field capacity, between 18 and 25 C and atpH 6–8. No germination occurred in autoclaved forest, dune, and agricultural soils or in gamma-irradiated or steamed Chehalis silt loam; however, 65–80% germination occurred in most nonsterile soils and in both autoclaved and nonsterilized kaolin and activated charcoal. Germination was similar in nonsterile Chehalis soil containing nonmycorrhizal, ectomycorrhizal, or vesicular-arbuscular (VA) mycorrhizal hosts, even Two other VA-mycorrhizal fungi,Glomus mosseaeandGigaspora gigantea, germinated readily in nonsterile soil as well. Optimum germination of spores seems closely related to conditions that are optimum for growth of many host plants.

ISSN:0027-5514    

DOI:10.1080/00275514.1980.12021207

出版商:Taylor&Francis    

年代:1980

数据来源: Taylor

摘要:

SUMMARYFruit bodies ofNidularia pulvinatawere grown in the laboratory on a special nutrient-supplemented straw medium. Fruit bodies were cryo-sectioned, fixed, dehydrated, critical-point dried, and observed in a scanning-electron microscope. Young fruit bodies were clearly differentiated into an upper portion and a lower portion where peridiole formation began. The peridium of young fruit bodies was composed of dense spinose skeletal hyphae which differentiated into three layers as they matured. The peridioles were formed from spherical aggregations of hyphae. They eventually developed a three-layered cortex. The peridioles gradually became oval with a central cavity in which basidiospores were produced. Four basidiospores on long sterigmata were formed on each basidium. Distribution of gelatinous material appeared to be correlated with development. Some similarities in ultrastructure betweenNidulariaandCyathuswere noted.

ISSN:0027-5514    

DOI:10.1080/00275514.1980.12021208

出版商:Taylor&Francis    

年代:1980

数据来源: Taylor

摘要:

SUMMARYThe zygomyceteMucor mieheiis used by industry to produce an acid protease which coagulates milk in the process of making cheese. This study is the first step toward understanding the natural function of the enzyme. My studies of control of the acid protease ofM. mieheipresently show that in a defined medium a protein must be present for enzyme to to be produced. The enzyme activity was not derepressed in the absence of protein by limitation of nutrients. Cycloheximide blocked enzyme production. High levels of free amino acids (1%) appeared to repress enzyme activity. There appeared to be repression of enzyme activity in the presence of high levels of glucose, ammonium tartrate and magnesium sulfate. These observations were compared to the results of similar studies in other fungal systems.

ISSN:0027-5514    

DOI:10.1080/00275514.1980.12021209

出版商:Taylor&Francis    

年代:1980

数据来源: Taylor

摘要:

SUMMARYBrown kamé(truffle), or“kholasi,”is a local name forTerfezia claveryifound in Kuwait. The ascocarp characteristics and spore germination behavior of this truffle were studied and described. Fresh and sun-dried ascocarps were used as sources of spores; dried spores germinated faster than fresh ones. A comparison of spore germination showed thatT. boudierigerminated sooner from both fresh and dried samples and exhibited a lower germination rate thanT. claveryi.

ISSN:0027-5514    

DOI:10.1080/00275514.1980.12021210

出版商:Taylor&Francis    

年代:1980

数据来源: Taylor

摘要:

SUMMARYThe frequency of plasmodial sporulation in wild-type strain A ofPhysarum polycephalumdeclined from 51% in 1969 to 0% when it was routinely cultured by shaking in an axenic medium. The ability to sporulate was restored if plasmodia were cultured on oats. Plasmodia of wildtype strain K continuously maintained on oats sporulated as expected following illumination. Plasmodia of strain K when shifted to shaken culture lost their ability to sporulate; sporulation competence was restored after transfer and feeding on oats.

ISSN:0027-5514    

DOI:10.1080/00275514.1980.12021211

出版商:Taylor&Francis    

年代:1980

数据来源: Taylor

摘要:

SUMMARYCellular fatty acids of 85 strains ofCandida, representing seven species, were extracted from yeast cells by saponification and analyzed as methyl esters by use of gas-liquid chromatography. Very few or no differences were observed among the chromatograms of different species grown on media containing glucose, maltose or sucrose. By contrast, when the seven species were grown on lactose medium only, each produced a distinctive fatty-acid“fingerprint”characterized by the presence or absence of certain fatty-acids peaks on the chromatogram. With this new method, it was possible to identifyCandidaspecies within 3 h after they were obtained from subcultures ofCandidagrown for 24–72 h on lactose medium, as compared with 7–10 da for more conventional procedures. The sensitivity and speed of gas-liquid chromatography make it an attractive alternative to standard laboratory tests for identification ofCandidaspecies.

ISSN:0027-5514    

DOI:10.1080/00275514.1980.12021212

出版商:Taylor&Francis    

年代:1980

数据来源: Taylor

摘要:

SUMMARYMultiple myxamoebal clone crosses of the myxomyceteDidymium iridisresult in the production of a single Plasmodium even when it is theoretically possible to produce a number of plasmodia of different incompatibility phenotypes. The dominant survivor can be predicted beforehand by determining the value of the incompatible cytotoxicity potential of all the possible phenotypes since the dominant Plasmodium will have a higher relative toxicity value. This elimination of different plasmodial-incompatibility phenotypes from culture is viewed as one more manifestation of a self-nonself recognition system.

ISSN:0027-5514    

DOI:10.1080/00275514.1980.12021213

出版商:Taylor&Francis    

年代:1980

数据来源: Taylor

摘要:

SUMMARYExcrescences were observed on hyphal walls ofBipolaris ntaydisgrown under a variety of cultural conditions. These structures were more numerous on hyphae found in the older portions of the colony. By electron microscopy, it could be demonstrated that the excrescence was bounded by a surface pellicle. The latter is an electron-transparent layer which is detectable after its surface becomes coated with electron-opaque material. The pellicle was also found to continue away from the excrescence to form a surface layer over the hypha itself. Presumed young hyphae in the peripheral regions of the colony had neither a pellicle nor excrescences. The presence of a pellicle appears to account for the smooth appearance of the wall surface of older hyphae in contrast to the irregular, frayed appearance of younger hyphae.

ISSN:0027-5514    

DOI:10.1080/00275514.1980.12021214

出版商:Taylor&Francis    

年代:1980

数据来源: Taylor

摘要:

SUMMARYThe genevacua(va) is a threshold gene which causes the transition from female sex organs (protoperithecia) to fruit bodies (perithecia). It does not effect spore formation.Vacuaperithecia are sterile and contain only proliferating paraphyses. Thusvaacts independently of the mating type genes (+ and -) which block fertilization in homokaryons and the completion of the sexual cycle. The mating type andvacuagenes are not linked. These findings allow the conclusion that, as in many higher Basidiomycetes, morphogenesis inPodosporais not related to the sexual cycle. This has a practical implication, since in many fungi of industrial value the production phase is correlated with morphogenetic alterations.

ISSN:0027-5514    

DOI:10.1080/00275514.1980.12021215

出版商:Taylor&Francis    

年代:1980

数据来源: Taylor