共查询到20条相似文献,搜索用时 15 毫秒
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- 1. The percentage of chrysanthemum pollen stained with Nitroblue tetrazolium ranged from 60 to 90 %, indicating the presenceof active succinate dehydrogenase in the pollen.
- 2. Exogenousapplication of oligosaccharides such as sucrose,lactose andraffinose at concentration of 20 to 35 % favoredgerminationof chrysanthemum pollen. However, the germinationrate was notelevated higher than 10 % in most of the chrysanthemumcultivars.
- 3. Sugar content of chrysanthemum pollen was less than 10%of the fresh weight. The sugar was composed of glucose, fructoseand sucrose, the amount of sucrose being about four times asmuch as that of glucose or fructose.
- 4. The ß-fructofuranosidaseactivity of chrysanthemumpollen was very high. These and relevantresults suggest thatthe poor germination of chrysanthemum pollenis due neitherto abortion nor to the deficiency of specialsugars in the pollen.
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Andrea Mathias Eva Kisdi 《Proceedings. Biological sciences / The Royal Society》2002,269(1487):151-155
Evolution of the germination rate (the proportion of newly produced and dormant seeds that germinates every year) of annual plants is investigated, when the environment is temporally stochastic and spatially heterogeneous. The environment consists of two habitats with synchronous stochastic variation in the annual yield and permanent difference in constant seed survival rates. Density dependence operates within the habitats, which are connected via restricted seed dispersal. We find that instead of a single common evolutionarily stable strategy the coexistence of several germination strategies is possible and that in an initially monomorphic population evolutionary branching may occur. During evolutionary branching the population undergoes disruptive selection and splits into two branches of different lineages that converge to the evolutionarily stable coalition of different germination strategies. It is shown that spatial heterogeneity and restricted dispersal are essential for evolutionary branching. Disruptive selection on the germination rate presents yet another possibility for parapatric speciation. 相似文献
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Seed dormancy and germination. 总被引:25,自引:0,他引:25
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Phytochrome and seed germination. V. Changes of phytochrome content during the germination of cucumber seeds 总被引:2,自引:2,他引:0 下载免费PDF全文
Cucumber seeds are light-sensitive, dark-germinating seeds. Inhibition of germination can be induced by prolonged exposure to continuous or intermittent FR. The dark germination process and the response to FR are phytochrome controlled. Phytochrome can be detected in these seeds by differential spectrophotometry in vivo. Spectrophotometrically measurable phytochrome increases during dark germination. The rate of increase is temperature dependent. Light treatments which are inhibitory for germination result in phytochrome contents lower than those of the seeds germinating in darkness. Treatments which restore germination also restore phytochrome formation. 相似文献
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Seed germination studies onTrichodesma amplexicaule were carried out. Seeds show abnormal behaviour of germination which is termed "Chalazal germination". This abnormal behaviour of germination is due to the presence of an obturator at the micropylar end. Seeds showed maximum (60 per cent) germination with 110 min concentrated H2SO4 treatment. 相似文献
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Triggering of germination in Bacillus megaterium QM B1551 spores with D-glucose was studied. First, the interaction of glucose with spores for less than 1 min resulted in triggering almost 90% of the spores after the glucose was removed by dilution. Therefore only a brief time is needed for glucose to trigger germination, and then the continuous presence of glucose is not necessary. Detectable uptake of glucose began 2 to 3 min after absorbance loss started, and a non-metabolizable glucose analog, methyl-alpha-D-glucopyranoside, triggered germination in the absence of detectable uptake. Several inhibitors that reduced or eliminated glucose uptake did not block triggering of germination. Therefore, glucose uptake may be a relatively late event and not a prerequisite for triggering of germination. 相似文献
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The role of the diamine putrescine during germination and outgrowth of ascospores of Saccharomyces cerevisiae was examined. Ornithine decarboxylase activity increased and declined rapidly during germination and outgrowth; peak activity was attained after the cells had proceeded through the G1 interval of the cell cycle, whereas minimal activity was present at the completion of the first cell division. alpha-Methylornithine inhibited both ornithine decarboxylase activity and the in vivo accumulation of putrescine. In the presence of alpha-methylornithireak dormancy and proceed through one cell division. Subsequent cellular growth, however, was retarded but not completely inhibited. The supplementation of Methylglyoxal bis(guanylhydrazone) to sporulation medium greatly inhibited this sexual process. These data suggest that the synthesis of putrescine is not required for the breaking of spore dormancy, but that polyamine biosynthesis may be essential for meiosis and sporulation. 相似文献
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Encystment and germination in Azotobacter vinelandii. 总被引:14,自引:0,他引:14
H L Sadoff 《Bacteriological reviews》1975,39(4):516-539
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H L Sadoff 《Microbiological reviews》1975,39(4):516-539
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Properties of Bacillus megaterium temperature-sensitive germination mutants. 总被引:3,自引:1,他引:2 下载免费PDF全文
J C Vary 《Journal of bacteriology》1975,121(1):197-203
Bacillus megaterium mutants JV-9 and JV-10 are temperature sensitive for initiation of spore germination. At 46 C, they did not lose heat resistance, dipicolinic acid, or absorbance, indicating that the temperature-sensitive blocks are very early in the sequence of initiation reactions. Strain JV-9 was temperature sensitive for initiation by glucose alone, and strain JV-10 was temperature sensitive for initiation by glucose, L-leucine, L-proline, KBr, or calcium dipicolinate. The kinetics of initiation were followed after two kinds of temperature change (shift-up and shift-down) experiments. Mutant spores incubated for different times at 46 C and then shifted down to 30 C showed no significant differences in the rates of absorbance decrease, i.e., no stimulation or inhibition. Conversely, when mutant spores were incubated for different times at 30 C, a fraction of the population initiated germination, and after shift-up to 46 C an additional fraction continued initiation while a third fraction stopped. This latter fraction did initiate germination when the temperature was lowered to 30 C. The kinetics of initiation after shift-up and shift-down in temperature suggest that the early events in initiation reagents, whereas the other four initiated sensitivity for all of the above initiation reagents, whereas the other four initiated very poorly. It was suggested that the lesion in strain JV-10 may result in the formation of one temperature-sensitive protein. Revertants of strain JV-9 could not be isolated. 相似文献
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Using several kinds of criteria for the germination of bacterial spores, germination-pH curves were drawn for Bacillus subtilis spores observed at different temperatures. The experiments revealed that optimum pH for spore germination was markedly changed by changing the incubation temperature; the optimum pH for germination was 7.4 at 37 degrees C and 5.4 at 10 degrees C. A possible mechanism involved in this phenomenon is discussed. 相似文献
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