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31.
Summary Pollen size and pistil length data have been collected for 93 species of Rhododendron (Ericaceae) belonging to a number of different subgeneric taxa. For a sample of eight species in section Vireya, pollen tube growth in the style after selfor interspecific pollination has been quantified. Pollen volume and the time taken for pollen tubes to reach the ovary were both related to pistil length. Pollen-tube growth rates were generally greater for species with longer pistils and larger pollen. Increasing temperature increased the rate of pollen-tube growth. There was no detectable effect of pollen tube density on tube growth rate in the style. After interspecific pollinations tube growth rates in foreign styles could be faster or slower than in self styles. A semisterile individual with two viable pollen grains per tetrad and a plant grafted as scion to a longer-styled stock both showed more rapid pollen-tube growth than expected on the basis of pistil size. Data collected for 26 species in section Vireya showed that where extreme disparity of pollen/pistil size causes failure of interspecific crosses, one or more bridging species with intermediate pollen/pistil size can generally be selected. 相似文献
32.
小麦—天兰偃麦草—黑麦三属杂种花粉植株诱导条件的研究 总被引:3,自引:1,他引:2
研究表明,三属杂种处于单核中晚期阶段的花粉最适于诱导形成愈伤组织。低温预处理对促进三属杂种花粉愈伤组织的诱导有一定的作用。利用以马铃薯提取物为基础物质的马铃薯-Ⅱ培养基作诱导培养基,其愈伤组织诱导与分化的频率比目前两个较好的合成培养基要高。同一个三属杂种F_1春、秋播种植株之间在形成愈伤组织的能力上有较大的差异,秋播材料形成愈伤组织的能力明显高于春播材料。F_(?)杂种植株诱导愈伤组织和分化植株的频率均比F_1杂种明显提高。 相似文献
33.
Transitions in the growth limiting factor from light (I) to nitrogen (N) and vice versa caused changes in geosmin production, protein and carbohydrate content, and the synthesis of pigments such as chlorophyll a (Chl a), phycobiliproteins (PBPs), and -carotene of the cyanobacterium Oscillatoria brevis. Following IN transition the first 150h, the decrease in protein content was compensated for by an increase of carbohydrates, and thereby, a constant biomass level was maintained in this period. Thereafter, biimass dropped to 15% of its initial level. A decrease in geosmin and pigment content was observed during transition from IN-limited growth. However, geosmin increased relative to phytol (Chl a) and -carotene which may indicate that a lowered demand for phytol and -carotene during N-limited growth allows isoprenoid precursors to be directed to geosmin rather than to pigment synthesis. Synthesis of Chl a and -carotene at the expense of geosmin was suggested for the observed start of increase in geosmin production only at the time that Chl a and -carotene had reached their I-limited steady state. Transition from nitrogen to light limited growth caused an acceleration of metabolism shown by a rapid decrease in carbohydrate content accompanied by an increase in protein content. The growth rate of the organisms temporarily exceeded the dilution rate of the culture and the biomass level increased 6-fold. Due to the only modest changes in geosmin production (2-fold) compared to changes in biomass level (6-fold) during I-or N-limited growth, environmental factors seem to have limited effect on geosmin production.Abbreviations Chl a
chlorophyll a
- dry wt
dry weight;
- I-limited
light-limited
- N-limited
nitrogen-limited
- PBP
phycobiliprotein
This research was performed at the Department of Microbiology, University of Amsterdam, with finacial support provided by the Royal Norwegian Ministry of Foreign Affairs and the Royal Norwegian Council for Scientific and Industrial Research 相似文献
34.
35.
Summary
Leucaena leucocephala generally produces pods with more than 7–9 seeds. This is regulated by the stigmatic inhibition of pollen grain germination when the pollen grains are less than a critical number in the stigma. This number-dependent inhibition of pollen grain germination is effected by a pH-dependent proteinaceous inhibitor active at the stigmatic pH. Only when the pollen grains in the stigma exceed the critical number, they inactivate the inhibitor by collectively raising the stigmatic pH and thus overcoming the inhibition. The adaptive significance of such pre-fertilization mechanism for the female in inciting mate competition among the pollen grains is discussed. The evolution of en masse pollen grain dispersal units is explained as a sexual selection strategy by males in response to such stigmatic inhibition by females. 相似文献
36.
A polyclonal antiserum and monoclonal antibodies have been prepared to purified pollen exines of Calocedrus decurrens Florin. The location of the antigen is in the exine, as shown by light-and electron-microscopic immunocytochemistry. The greatest reduction in antibody binding follows treatment of the exine with chemicals known to alter sporopollenin. These results provide evidence that sporopollenin is antigenic. Exines of ten species of gymnosperms and angiosperms also bound the polyclonal antiserum, indicating similarity of sporopollenin structure. 相似文献
37.
R. J. Bino J. Franken H. M. A. Witsenboer J. Hille J. J. M. Dons 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》1988,76(2):204-208
Summary Effects of the phytotoxic compounds (AAL-toxins) isolated from cell-free culture filtrates of Alternaria alternata f.sp. lycopersici on in vitro pollen development were studied. AAL-toxins inhibited both germination and tube growth of pollen from several Lycopersicon genotypes. Pollen from susceptible genotypes, however, was more sensitive for AAL-toxins than pollen from resistant plants, while pollen of species not belonging to the host range of the fungus was not significantly affected by the tested toxin concentrations. AAL-toxins elicit symptoms in detached leaf bioassays indistinguishable from those observed on leaves of fungal infected tomato plants, and toxins play a major role in the pathogenesis. Apparently, pathogenesis-related processes and mechanisms involved in disease resistance are expressed in both vegetative and generative tissues. This overlap in gene expression between the sporophytic and gametophytic level of a plant may be advantageously utilized in plant breeding programmes. Pollen may be used to distinguish susceptible and resistant plants and to select for resistances and tolerances against phytotoxins and other selective agents. 相似文献
38.
诱导小麦-天兰偃麦草-黑麦三属杂种花粉植株的研究 总被引:2,自引:2,他引:0
以法国六倍体小黑麦为母本,分别与普通小麦(Triticum aestivum)和天兰偃麦草(Elytrigia intermedia of Agropyron glaucum)的杂交后代中的中间类型3号和5号杂交。由此获得的三属杂种F_1性状介于亲本之间,兼有三属亲本类型的特征,呈中间类型。用马铃薯-Ⅱ培养基培养三属杂种F_1的花药,诱导花粉愈伤组织。将所获得的愈伤组织转入190-2培养基进行分化,已成功地诱导出一批三属间杂种花粉植株,并用Giemsa显带技术鉴定花粉植株的染色体组组成。 相似文献
39.
Summary An attempt was made to transfer two sorts of DNA into maize via pollen grains. Controls for both pollen quality and DNA behaviour during the transformation experiments were included. When genomic DNA was used, no transformants were observed among the 1805 seeds screened. With plasmid DNA (harbouring the gene expressing kanamycin resistance in plant cells), three plants with kanamycin resistance were observed among the 1723 seeds screened, although no molecular evidence of transformation was obtained. Experiments indicated that under the conditions used, DNA was being degraded by both pollen and stigma nucleases. Consequently, we attempted to determine protocols which would inhibit these nuclease activities in order to preserve DNA integrity during transformation experiments, thus allowing fertilization. We found that a classic germination medium supplemented by 300 or 600 mM KNO3, or 20% PEG1550 satisfied all these conditions.Abbreviations BK
Brewbaker and Kwack medium
- BKS15
Brewbaker and Kwack medium containing 15% (w/v) sucrose
- EDTA
ethyldiaminetetraacetic acid
- FCR
fluorochromatic reaction
- FP
fertilization percentage
- PEG
polyethylene-glycol 相似文献
40.
Summary A typical style of Hypericum calycinum is solid with a core of transmitting tissue traversing the whole length of the style. This transmitting tissue consists of loosely arranged cells and large intercellular spaces filled with a secretion product. The secretion product is rich in lipids, but poor in proteins and polysaccharides. The intercellular spaces of the transmitting tissue originate partly by a separation of cells as a result of the decomposition of the middle lamella and partly by degeneration of some of the cells of the transmitting tissue. H. calycinum is self-compatible. Both self- and cross-pollinations result in profuse pollen germination on the stigma and pollen tube growth through the style. The data on Hypericum is discussed in relation to information available on other solidstyled systems. 相似文献