摘要:

Abscission of debladed petioles ofColeuswas observed following spray applications of gibberellic acid (GA) to the foliage. Sprays were applied to some branches which were left intact (inducing branches), or to adjacent branches whose leaves were later debladed (induced branches). In all experiments three applications of GA were made after which the induced branches were debladed, but in one series deblading was delayed for a week after the last spray application. All treatments resulted in accelerated petiole abscission relative to the controls. Differences between the results of these experiments and the results of similar, earlier experiments with indoleacetic acid (IAA) are discussed. The evidence suggests that GA accelerates abscission by a different mechanism than does IAA.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1976.tb11794.x

出版商:Wiley    

年代:1976

数据来源: WILEY

摘要:

Single pore studies of 27 isolates ofDidymium iridisfrom several geographical locations revealed that 11 are heterothallic, displaying a one‐locus, multiple allelic mating system. Collectively, 9 of the 11 possess a total of 12 mating types in one multiple allelic series. Each of the remaining two isolates has a pair of mating types which are either incompatible with the 12 or they have not yet been tested against them. Sixteen isolates proved to be homothallic.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1976.tb11795.x

出版商:Wiley    

年代:1976

数据来源: WILEY

摘要:

Phialide formation inAspergillus clavatusbegins with the formation of thin areas in the vesicle wall. These thin‐walled regions and adjacent cytoplasm then push out synchronously to produce the phialides. Mature phialides are broadly oval with an attenuated base and tapered apex. A secondary wall forms inside the phialide apex. The entire phialide apex pushes out to form the first conidium which is delimited by formation of a septum inside the mouth of the phialide. No collarette is present as the first conidium forms, but as the second conidium begins to develop, the outer wall breaks at the mouth of the phialide, leaving a collarette. The walls of the second and subsequent conidia are continuous with the inner wall of the phialide apex, from which they form. Conidia are held in chains by a connective which is a greatly thickened septum.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1976.tb11796.x

出版商:Wiley    

年代:1976

数据来源: WILEY

摘要:

Seed proteins from the tetraploidGaleopsis tetrahitL. and its putative parental speciesG. pubescensBess. andG. speciosaMill., were examined using disc gel electrophoresis (PAGE), Ouchterlony double diffusion, and Immunoelectrophoresis. Forty‐three inbred cultivated lines ofG. speciosa, G. pubescens, andG. tetrahit(both the naturally occurring species and an artificially produced hybrid) and two wild populations ofG. tetrahitwere examined. PAGE gels were stained for total protein or malate dehydrogenase. Although variability in the total protein pattern was detected within and between lines for all three species, there was much similarity among the taxa. No bands appeared in the hybrid that were not present in the parents. The band pattern for syntheticG. tetrahitwas very similar to that of naturalG. tetrahitsuggesting thatG. tetrahitoriginated from a cross in nature betweenG. pubescensandG. speciosa.The total protein PAGE results were analyzed using numerical taxonomic techniques. Although these analyses did not clearly separate the three species, the general tendency was toward groupingG. pubescenslines together, naturalG. tetrahitlines together, and syntheticG. tetrahitlines together. Natural and syntheticG. tetrahitlines were also interspersed among each other along with someG. speciosalines. The malate dehydrogenase pattern showed little variation among the three species. Qualitative serological methods did not distingush among the three species, but confirmed the similarity observed among the taxa in the results of electrophoresis.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1976.tb11797.x

出版商:Wiley    

年代:1976

数据来源: WILEY

摘要:

Vegetative plants ofXanthium strumarium(a short‐day species) were induced to flower by exposure to a single 16‐hr long night. By cutting off the induced leaf (half‐expanded leaf) at various times, it was established that, by 8 hr after the end of the long night, a sufficient amount of floral stimulus had reached the meristem to induce a flowering response. The following sequence of events occurred in both the peripheral and central zones of the apical meristem of induced plants: 1) a rise in the mitotic index beginning at 28 hr after the end of the long night and culminating at 36 and 56 hr; 2) a stimulation of DNA synthesis starting at 32–36 hr and reaching a maximum at 60 hr; 3) an increase in nucleolus diameter starting at 32 hr. The cell population in the meristems of both vegetative and induced plants displayed a similar distribution, with about 80 % of the nuclei with the 2C amount of DNA. The comparison of the kinetic data concerning the mitotic index and DNA synthesis indicated that one of the early effects of the floral stimulus in the peripheral and central zones was the release in mitosis of cells whose nuclei were in the postsynthetic (G2) phase of the mitotic cycle. In the pith‐rib meristem, the following events were recorded: 1) a stimulation of DNA synthesis starting at 20 hr; 2) a rise of the mitotic index beginning at 28 hr; 3) the vacuolation and elongation of cells starting at 48 hr. All these events occurred well before the initiation of bract and flower primordia, which began at 96 and 136 hr, respectively. Neither stimulation of mitotic activity nor flowering occurred in the meristems of plants subjected to a long night interrupted at its midpoint by a 5‐min light break. The results are discussed in relation to the early events which are known to occur in the meristems of other photoperiodic species in transition to flowering.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1976.tb11798.x

出版商:Wiley    

年代:1976

数据来源: WILEY

摘要:

Carpel closure and stigmatic localization in the Alismatales have accompanied decreases in carpel size and numbers of ovules per carpel and increases in carpel numbers per flower. The most specialized carpels are uniovulate and indehiscent and occur acyclically in great numbers in each flower, with strong trends toward monoecism and even dioecism. The least specialized carpels in the order are open, multiovulate, and conduplicate, with poor differentiation of style and stigma. The Alismatales show a broad range from primitive to specialized gynoecial features.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1976.tb11799.x

出版商:Wiley    

年代:1976

数据来源: WILEY

摘要:

Physiological aspects of phosphate utilization by the blue‐green algaPlectonema boryanumwere studied. It was found that the external phosphate concentration influenced the distribution of phosphorus‐containing compounds in the cell. Culturing the alga in concentrations of 10, 100, and 1000 mg PO4/l resulted in increases in the level of acid‐soluble and acid‐insoluble polyphosphates. The values reported for 100 and 1000 mg PO4/l were the same, indicating that the cells were able to assimilate and utilize only fixed amounts of phosphates. The total phosphorus value for these cells was calculated to be 6.5 μg P per 106cells. Culturing the alga in 1 mg PO4/l led to a decrease in phosphate concentration of all cell fractions. Cells grown in the absence of phosphate for 5 days had total cell phosphorus levels of 0.76 μg P per 106cells. Cells in culture for two months or longer were found to have total cell phosphorus levels of 0.73 μg P per 106cells. This was determined to be the minimum cell phosphorus level limiting growth. Transfer of cells from either culture condition to a medium containing phosphate led to an “overplus” phenomenon. This overplus phenomenon was characterized by increases in all cellular phosphorus fractions. The most dramatic increase was found in both the acid‐soluble and acid‐insoluble polyphosphates. These fractions often increased by more than an order of magnitude. The greatest phosphate uptake occurred within 1 hr of transfer of phosphate‐starved cells into a medium containing a known amount of phosphate and is essentially complete at 4 hr. The total cell phosphorus levels for uptake never increased beyond 18.9 μg per 106cells.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1976.tb11800.x

出版商:Wiley    

年代:1976

数据来源: WILEY

摘要:

Arctostaphylos glaucahas evolved two growth forms in the San Bernardino Mountains of Southern California. A chaparral ecotype of upright shrubs with relatively long leaves occurs in chaparral on the south and west sides of the mountain range. A desert woodland ecotype of low, compact, spreading shrubs with shorter leaves occurs in pinyon woodland on the north and northeast sides of the same range. The chaparral ecotype flowers early and fruits heavily. Upon periodic destruction by fire its populations are replaced by numerous seedlings. The woodland ecotype flowers late and fruits sparingly. Its lower seed reproductive potential is further indicated by the lower total number of floral units, by a lower proportion of fruit set, and by an apparent truncation of the flowering season before all the flower buds open. An alternative strategy, involving long life, compact growth form, and the exploitation of new soil resources by layering and vegetative reproduction in the absence of regular fire recycling has evidently adapted an old chaparral plant to recent desert woodland conditions.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1976.tb11801.x

出版商:Wiley    

年代:1976

数据来源: WILEY

摘要:

Volatile monoterpenes emanating from leaves ofSalvia leucophylla(Labiatae) are responsible for anatomical and physiological changes occurring in herb seedlings which were exposed to the vapors. Examination of treated root tip cells fromCucumis sativusby electron microscopy revealed widespread systemic disturbances. These included the accumulation of globules which appear to be lipid in nature in the cytoplasm, a drastic reduction in the number of a variety of intact organelles including mitochondria, and a disruption of membranes surrounding nuclei, mitochondria, and dictyosomes. These effects, coupled with the effects of environmental stress, may account for the failure of herb seedlings to survive in the areas adjacent toSalviathickets.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1976.tb11802.x

出版商:Wiley    

年代:1976

数据来源: WILEY

摘要:

WholeCymbidiumSw. (Orchidaceae) flowers, ones with their labella, gynostemia or perianth removed as well as excised ovaries, lips and columns, were pollinated, emasculated and treated with NAA and maintained in media containing or lacking NAA. The results indicate that, 1) the rostellar‐stigmatic region seems to control many post‐pollination phenomena, 2) auxin from the medium apparently does not reach the rostellum and/or stigma, 3) there is a certain interdependence among floral segments which exhibit post‐pollination phenomena, and 4) once initiated, these phenomena may be subject to localized effects. These findings are taken as an indication that pollinated orchid flowers are a well‐integrated system despite the diversity and number of observable phenomena.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1976.tb11803.x

出版商:Wiley    

年代:1976

数据来源: WILEY