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Jacques Padawer 《The Journal of cell biology》1966,29(1):176-180
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秋水仙素对小麦根尖细胞亚显微结构的影响 总被引:2,自引:0,他引:2
在不同浓度和处理时间下用秋水仙素处理小麦很尖,发现根尖分生区细胞的亚显微结构发生了程度不同的变化。表现在核占细胞体积的比例减小,形态变化多样;内质网由分散分布到形成聚集体;原质体减少而淀粉质体增加;微体减少;液泡增大;细胞壁不均匀地加厚且细胞间隙增大等方面。初步讨论了秋水仙素引起的微管解聚是内质同、质体、微体、核等所处的状态和细胞壁不均匀加厚的主要原因。探测了秋水仙素对小麦根尖细胞亚显微结构影响的一般临界浓度和处理时间。从结果看,秋水仙素处理小麦根尖分生区细胞后,其原有的状态发生了改变,导致了分生细胞从胚性转向分化。 相似文献
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We measured outcrossing rates of several North Carolina populations of the annual weed Datura stramonium including both natural populations and experimental populations in which we manipulated plant spatial arrangement. Because capsules of D. stramonium typically produce hundreds of seeds and we used an easily scored genetic marker for flower and hypocotyl color, we could measure outcrossing rates accurately for both individual plants and single flowers. The population-wide estimates of outcrossing rates were surprisingly low for a species with showy, entomophilous flowers and ranged from 1.9% in an experimental population with a “clumped” spatial arrangement to 8.5% in an experimental population with a “dispersed” arrangement. These low values were not produced by pollinator discrimination among flower color morphs, as determined by outcrossing measurements on test plants of different colors and by direct observations of pollinator behavior. For individual plants and single flowers in the experimental populations, variation in outcrossing rates was significantly affected by such population-wide characteristics as plant spatial arrangement and nightly fluctuations in total floral abundance. However, by far the most important factor was stigma position. Flowers with stigmas above the anthers had significantly higher outcrossing rates than did flowers with overlapping stigma and anthers. The strong effect of floral morphology suggests that the very low population-wide levels of outcrossing in D. stramonium may represent a persistent mixing mating system rather than a transition to complete selfing. 相似文献
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