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植物激素对棉属种间杂种胚乳细胞超微结构发育的影响 总被引：2，自引：0，他引：2
本文报道了陆地棉和亚洲棉杂交时，喷施植物激素（ＧＡ３，ＮＡＡ）后，对杂种胚乳细胞超微结构发育的影响。观察发现，（１）外源激素对原胚期的杂种胚乳细胞发育的影响不显著，但明显地促进了胚乳细胞中管状内质网的发育。（２）外源激素能明显促进杂种胚乳细胞中的内质网、质体和线粒体等细胞器的发育，使杂种胚乳细胞保持有一定的发育能力。（３）外源激素未能促进杂种胚乳细胞中核糖体和多聚核糖体的形成，也未能促进液泡和囊泡的发育，杂种胚乳细胞之间仍缺少胞间连丝，因此，喷施激素后的杂种胚乳细胞总是没有自交胚乳细胞那样旺盛地分裂与发育。 相似文献
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种子发育及其调控机制是发育生物学中重要的问题。在被子植物中,种子发育从双受精事件开始,继而形成二倍体胚和三倍体胚乳,种皮包裹着胚和胚乳,胚、胚乳和种皮协调生长和调控,从而确定种子的最终大小。种子生长主要由合子组织和母体的内部遗传信息控制。种子大小可通过调节胚乳生长来控制,即种子大小取决于合子组织的基因型。母体为胚胎和胚乳的生长提供空间,种皮发育决定种子大小的上限,说明母体组织的基因型也调控着种子的大小。目前已知控制种子大小的信号途径主要有:IKU(HAIKU)通路、泛素-蛋白酶体通路、G(Guanosine triphosphate)蛋白信号通路和丝裂原活化蛋白激酶(mitogen-activated protein kinase,MAPK)信号通路,植物激素和转录调节因子。本研究综述了拟南芥和水稻两种模式植物种子大小调控的研究进展,主要围绕调控因子的遗传和分子机制展开。 相似文献
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<正>基因组印记(genetic imprinting)是一种非常重要的表观遗传学现象之一。在配子或合子发育过程中,来自亲本的等位基因或染色体发生了差异的表观修饰,导致了亲本等位基因的差异表达(即印迹基因)。在植物中基因组印迹主要发生在被子植物的三倍体胚乳组织中,且在胚乳以及种子的发育过程中扮演着重要的作用,但由于拟南芥胚乳随着种子发育 相似文献
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大麦胚乳发育过程中贮藏蛋白的积累和蛋白体的形成 总被引：1，自引：1，他引：0
利用光学显微镜和电子显微镜技术观察了大麦胚乳发育过程中贮藏蛋白的积累和蛋白体的形成。抽穗后8 d的胚乳细胞,富含内质网和蛋白贮藏液泡(PSV),少量淀粉粒沿细胞核或细胞膜分布。贮藏蛋白颗粒在抽穗后10 d的胚乳细胞中开始出现,内质网的腔膨大,积累贮藏蛋白,后脱离内质网形成蛋白体。在胚乳细胞生长分化早期,蛋白体呈球状进入PSV;随着胚乳发育,贮藏蛋白体急剧增多,以亚糊粉层细胞为主。在胚乳细胞生长分化中期,PSV充满蛋白体,其周围有电子致密物质;新产生的蛋白体在细胞质基质中呈球状聚集在一起。在胚乳细胞生长分化后期,PSV中的部分蛋白体或者细胞质基质中的部分蛋白体开始相互融合,同时内质网衍生出许多小蛋白体分散在淀粉粒之间。在胚乳发育成熟期,蛋白体相互融合形成无定形的蛋白质基质分布在淀粉粒间的间隙中。结果表明,大麦胚乳发育过程中,内质网衍生出蛋白体,聚集于PSV或细胞质基质中,然后相互融合形成成熟籽粒的蛋白质基质。 相似文献
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<正>玉米胚乳发育包括两个过程,一是胚乳细胞进行分裂增殖和生长扩大,淀粉粒在胚乳细胞中形成,即籽粒库容的建成;二是淀粉不断合成、积累,胚乳细胞中的淀粉粒逐渐膨大,即籽粒库的充实。激素是一种重要的生理活性物质,任何器官的发育都依赖于激素平衡和有效同化物之间的相互作用。籽粒的生长发育是细胞分裂、分化、膨大和内含物不断充实的过程,研究结果认为:四大内源激素(CTK、ABA、IAA、GA)对籽粒的发育过程都有调控作用。 相似文献
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本文对普通小麦与六倍体小黑麦这一组远缘杂交的不亲和性,从胚胎学的角度进行了研究。以六倍体小黑麦作母本,杂种胚胎发育与亲本的差异较小;以普通小麦作母本,杂种胚发育逐渐表现出显著的异常,最终是胚败育,种子失去生活力。通过对胚的切片的解剖观察和胚离体培养的研究,表明在以普通小麦作母本的杂交种子中,胚乳的发育异常发生在胚败育之前,及时将胚取出作离体培养可以发育成苗,因而证明胚的败育是由胚乳的异常发育引起的。本文讨论了这些杂交种子中胚乳发育的不同情况对胚的不同影响。 相似文献
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玉米授粉后的10—12天是玉米籽粒发育的一个关键时期。这个时期决定着籽粒以后的生长和发育。决定着胚乳积累干物质的能力,并且影响着形成胚乳细胞和淀粉粒的数目,在玉米的生殖生长期间,外界温度经常比它所需要的最适温度高,在最适温度(25℃)以上,每增加1℃将导致籽粒产量降低3%—4%,因此研究高温胁迫对玉米籽粒发育的破坏和限制机制非常重要。 我们实验室的研究表明:在玉米胚乳细胞分裂和淀粉体生物合成期间,高温胁迫使胚乳细胞的分裂速率和持续时间降低。因此,导致细胞的数目和淀粉体的 相似文献
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Abscission or retention of ripening fruit is a major component of seed dispersal strategies and also has important implications
for horticultural production. Abscission-related traits have generally not been targeted in breeding efforts, and their genetic
bases remain mostly unknown. We evaluated 144 Malus accessions representing wild species, domestic cultivars, and hybrids for abscission-related traits. We found that seasonal
timing of fruit abscission in wild species and hybrids showed a broad distribution similar to that seen for domestic cultivars,
and that internal ethylene concentration at the time of abscission varied by over three orders of magnitude. Wild species,
domestic cultivars, and hybrids all included representatives that showed abscission of fruit prior to substantial production
of ethylene, as well as accessions that retained fruit for a significant period of time following ethylene production. For
all accessions that retained fruit, fruit removal resulted in abscission of the pedicel, and exogenous ethylene promoted abscission,
suggesting that the abscission zone was functional. Our results suggest important roles for mechanisms independent of fruit
ethylene production in abscission. 相似文献
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为方便资料用户准确地把握霍尔果斯站的气候资料信息,进而揭示真实的气候变化特征与规律,选取霍城和伊宁县作为参考站,利用霍尔果斯站和参考站1961—2014年的同期观测资料序列进行了完整性、区域一致性和均一性分析。发现,霍尔果斯站观测资料完整性好,但气温、降水、湿度和风速共4个要素的区域一致性均较差,并且均存在不连续点。同期对比观测资料分析结果表明,相对湿度、降水量和风速一致性较好,气温和风向一致性比较差。显著性检验结果表明,新址和旧址除年、月平均风速差异显著,不能连续使用外,其他5个要素基本通过了显著性检验,资料可以连续使用。而风速在资料服务中需要进行订正,方可连续使用。 相似文献
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Dimbab Ngidang 《Asia Pacific viewpoint》2002,43(2):157-180
Landowners and the private investors often have contradictory interests in joint ventures. Although development planners sometimes believe that government can harmonise these contradictions, state interests in development often lead them to support the interests of private capital. While joint ventures may be useful ways of pooling human, material and financial resources, this article draws on a case study of two pilot joint venture oil palm schemes in Sarawak, Malaysia, to show that the legal construction and administration of native customary land rights generate lower results for landowners than they do for the private sector. Information and power asymmetries constrain the ability of affected natives to realise fair benefits under a joint venture arrangement. When institutional constraints that give a measure of protection to native rights and interests are dismantled in the rush to establish commercial plantations for example, an unregulated market can be detrimental to landowners’ rights and long–term interests. 相似文献
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Nnadozie C. Oraguzie Madeleine E. Hofstee Lester R. Brewer Craig Howard 《Euphytica》2001,118(1):29-37
Combining ability was estimated for 8 tree and 11 agronomic traits in a multi-location apple genetics population to select
individuals for the next cycle of selections. Families more than three standard errors away from the general mean were identified
for each trait and extreme individuals (with regard to that trait) from those families were selected. On the whole, 148 individuals
were chosen based upon individual traits and, in a few cases a combination of traits, in a way that maintains the original
diversity within the population. Narrow-sense heritability estimated separately for each site for fruit ribbing, fruit russet,
fruit overcolour amount and fruit weight ranged from 0.0–0.13, 0.05–0.58, 0.34–0.40 and 0.27–0.90 respectively. Phenotypic
correlation and additive genetic correlation were small and from small to moderately high respectively, between pairs of traits.
The implication of these genetic parameter estimates in apple breeding is discussed.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
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Governing climate change in Hong Kong: Prospects for market mechanisms in the context of emissions trading in China 
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下载免费PDF全文 Hong Kong continues to struggle over which environmental governance approach is in its best interest while fulfilling its environmental obligations. With regard to climate change, Hong Kong's approach is characterised by a passive form of governance that is highly dependent on China's national policy directions. This is reflected, for example, in Hong Kong having not set its own mitigation targets. Market mechanisms have received little attention in developing a city‐wide climate change strategy. A transformative impulse, China's national emissions trading scheme, may provide momentum to a market‐based approach. However, the necessary conditions for such a market mechanism to be successfully implemented in China remain relatively undeveloped. This raises question about early participation by Hong Kong. Direct benefits are likely to be limited, due to Hong Kong's economic structure and weak demand for emissions reduction. Besides, there are regulatory barriers to enforcing emissions targets and/or recognising emissions allowances and credits from China. We therefore argue that nationwide emissions trading may, at this time, present more challenges than opportunities for Hong Kong to leverage its efforts on climate change mitigation. An alternative is to promote voluntary emissions trading that will require active involvement and leadership by businesses. 相似文献
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Data Mining can distill the connotative, unknown and potential value information or pattern from many data. It is a problem that must be settled during the developing of Decision Support System how to discover knowledge from Data Warehouse. In order to realize the continuous mathematical forecast that will be used in the Marketing Decision Support System for Industrial Enterprise, the authors use the method of regression to discuss how to design the algorithm for Data Mining, how to design the model for Data Mining, and so on. When the algorithm applied to the sales forecast, the result processing to simulation data indicates it can realize the expected effect. 相似文献
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Summary Substantial variation in tolerance to the triazine herbicide simazine was observed among a wide range of Brassica napus cultivars grown in a hydroponic screening system. None of these cultivars was as tolerant of are simazine treatment as the Canadian cultivar Triton which carries cytoplasmic gene(s) which confer a high level of resistance through their modification of chloroplast membranes to which triazine herbicides normally bind. A field study showed that the most tolerant cultivar Haya had a significantly higher yield than Triton in both handweeded plots and plots treated with 1000 ml/ha simazine. This finding supported other observations that the yield potential of cultivars such as Triton is substantially reduced because of the impairment of photosynthesis by cytoplasmic gene(s) for triazine resistance. A slight reduction in the yield of Haya with an increase in simazine concentration from 500 to 1000 ml/ha suggested that further increases in simazine concentration required for optimal weed control are likely to have a detrimental effect on the yield of Haya and other tolerant cultivars. Genetic analyses of variation in simazine tolerance in populations derived from crosses among cultivars representative of the range in tolerance indicated that the narrow-sense heritability of tolerance was of sufficient magnitude to allow for isolation of genotypes tolerant of higher simazine concentrations. These could be utilized in developing high yielding cultivars in areas of southern Australia where simazine treatment is necessary for effective weed control in Canola crops. 相似文献
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An extension of guarantees related to rainfall-related risks in the insurance of processing tomato crops has been accompanied with a large increase in claims in Western Spain, suggesting that damages may have been underestimated in previous years. A database was built by linking agricultural insurance records, meteorological data from local weather stations, and topographic data. The risk of rainfall-related damages in processing tomato in the Extremenian Guadiana river basin (W Spain) was studied using a logistic model. Risks during the growth of the crop and at harvesting were modelled separately. First, the risk related to rainfall was modelled as a function of meteorological, terrain and management variables. The resulting models were used to identify the variables responsible for rainfall-related damages, with a view to assess the potential impact of extending insurance coverage, and to develop an index to express the suitability of the cropping system for insurance. The analyses reveal that damages at different stages of crop development correspond to different hazards. The geographic dependence of the risk influences the scale at which the model might have validity, which together with the year dependency, the possibility of implementing index based insurances is questioned. 相似文献