Evolution of Pollen Development in Orchids

兰花花粉发育的演变

• 批准号: 9418015
• 负责人: Roy Brown
• 金额: $ 24万
• 依托单位: University of Louisiana at Lafayette
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 1995
• 资助国家: 美国
• 起止时间: 1995-03-15 至 1998-02-28
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9418015&HistoricalAwards=false
• 关键词: Evolution; Pollen; Development; Orchids

; R o o t E n t r y F t fB C o m p O b j b W o r d D o c u m e n t * O b j e c t P o o l t fB t fB F Microsoft Word 6.0 Document MSWordDoc Word.Document.6 ; Oh +' 0 D h @ d R:\WWUSER\TEMPLATE\NORMAL.DOT P:\CELL\ABSTRACT\9418015.ASC Una Solomon Una e = e / * / j j j j j j j M C / T F M j M j j j j ~ j j j j 7 9418015 Brown and Lemmon Pollen development in orchids is a promising new system for studying ontogenetic aspects of plant evolution. Precise nulcear and cytoplasmic divisions occur in both meiosis and pollen mitosis in the absence of a preprophase band of microtubules (PBB). In addition, microsporocytes differ in that karyokinesis and cytokinesis may be temporally uncoupled resulting in a brief coenocytic stage before simultaneous quadripartioning into a tetrad of microspores. In simulatneous cytokinesis, phragmoplasts develop between non-sister as well as siter nuclei providing additonal information on phragmoplast development and the determination of division plane. On the basis of recent comparative studies we have put forth the hypothesis that the direct control of division plane in cells lacking PPBs is a function of nuclear-based radial microtubule systems (RMS) that define domains of cytoplasm. The nuclear cytoplasmic domain model assumes that spindle alignment, and therefore placement of nuclei, stems from establishment of division polarity which, in turn may be subject to various levels of contol. We propose comparative, developmental and experimental studies of the organization and functional interactions among cytoskeletal elements (microtubules and F actin), organelles, and endomembranes in pollen development. Since the cytokinetic apparatus in microsporogenesis is much more variable than histogenesis, we will use comparative studies to identify commonalities that underlie events of pollen development. Both the microsprorocytes and pollen of orchids are amenable to modern methods of immunocytochemstry and electron microscopy. The generative pole microtubule system (GPMS), which we recently discovered in the exineless pollen of moth orchids, provides a targetable structural marker for drug perturbation sutdies aimed at understanding the establishment of polarity and organization of microtubles of the unequal first division in pollen that is critical to development of the male gametophyte. %%% This is a proposal by highly regarded senior investigators working on cytoskeletal involvement in establishing planes of cell division and on the formation of cytoplasmic domains which may orient division. The system they have selected, pollen formation in orchids, is chosen because underlying mechanisms are often revealed by thematic variation. The orchid family offers much variety in mode of meiotic and mitotic cytokinesis and in the availability of complex hybrids which undergo faulty meiosis during pollen formation. Pollen division is particularly interesting because the structure which determines the future site of cell division, the pre prophase band of microtubules, is missing. The goa ls of the proposal are to 1) investigate the establishment of division polarity in meiosis and pollen mitosis, 2) investigate the relationship of the radial microtubule system associated with the cell nucleus to the organization of the microtubules involved in laying down the daughter cell wall during division , 3) establish if cytoplasmic domains defined by co-extensive microtubules control the division plane during meiosis and pollen mitosis, and 4) relate the data on pollen development to the evolution of the diverse pollen types found in the Orchidaceae. With regard to objectives (2) and (3), this work has the potential to reveal the importance of nuclearassociated microtubules in microtubule growth and initiation in plants in general. Its identification as a microtubule organizing center (MTOC)cell biology. The microtubules of plants have been shown to have a dramatic influence on plant cell shape and size. The cortical array associated with the plasma membrane helps determines the axis of cell extension, while the array associated with the cell division plane helps determine the morphogenesis of plant tissues. These phenomena are the bases for the production of potent, selective herbicides which take advantage of the differences between plant, animal, and fungal cytoskeletal assembly. Work proposed here will offer additional insight into those mechanisms unique to plants which control cytoskeletal assembly. In addition, insights gained by this analysis of cytoskeletal involvement inthe nature of pollen formation in plants will contribute fundamentally to our knowledge about plant reproduction. *** ;

; 根条目 Ft fB Comp O b j b Word 文档 * 对象池 fB t fB F Microsoft Word 6.0 文档 MSWordDoc Word.Document.6； Oh +' 0 D h @ d R:\WWUSER\TEMPLATE\NORMAL.DOT P:\CELL\ABSTRACT\9418015.ASC Una Solomon Una e = e / * / j j j j j j j M C / T F M j M j j j j ~ j j j j 7 9418015 兰花中棕色和柠檬花粉的发育是研究兰花个体发育方面的一个有前途的新系统植物 进化。 在没有前期微管带 (PBB) 的情况下，减数分裂和花粉有丝分裂中都会发生精确的核核和细胞质分裂。 此外，小孢子母细胞的不同之处在于核分裂和胞质分裂可能暂时分离，导致在同时四分成小孢子四分体之前短暂的共生细胞阶段。在同时胞质分裂中，成膜体在非姐妹核和位点核之间发育，提供有关成膜体发育和分裂平面确定的附加信息。 在最近的比较研究的基础上，我们提出了这样的假设：缺乏 PPB 的细胞中分裂平面的直接控制是定义细胞质域的基于核的径向微管系统 (RMS) 的功能。 核细胞质结构域模型假设纺锤体排列以及细胞核的位置源于分裂极性的建立，而分裂极性又可能受到不同水平的控制。 我们提出对花粉发育中细胞骨架元件（微管和肌动蛋白）、细胞器和内膜之间的组织和功能相互作用进行比较、发育和实验研究。 由于小孢子发生中的细胞分裂装置比组织发生中的变化更大，我们将使用比较研究来确定花粉发育事件背后的共性。 兰花的小孢子细胞和花粉都适合现代免疫细胞化学和电子显微镜方法。 我们最近在蝴蝶兰的无外质花粉中发现了生殖极微管系统（GPMS），它为药物扰动研究提供了一个有针对性的结构标记，旨在了解花粉中不等第一分裂的微管的极性和组织的建立，这对于雄配子体的发育至关重要。 %%% 这是由备受推崇的高级研究人员提出的建议，他们致力于细胞骨架参与建立细胞分裂平面以及可能定向分裂的细胞质结构域的形成。 他们选择兰花花粉形成的系统，是因为主题变化往往揭示了潜在的机制。兰科植物在减数分裂和有丝分裂胞质分裂模式以及在花粉形成过程中经历错误减数分裂的复杂杂种的可用性方面提供了多种多样性。花粉分裂特别有趣，因为决定细胞分裂未来部位的结构（微管的前期带）缺失了。该提案的目标是 1) 研究减数分裂和花粉有丝分裂中分裂极性的建立，2) 研究与细胞核相关的放射状微管系统与分裂过程中参与铺设子细胞壁的微管组织的关系，3) 确定由共同延伸的微管定义的细胞质域是否控制减数分裂和花粉有丝分裂期间的分裂平面，4) 将花粉发育的数据与兰科植物中发现的多种花粉类型的进化联系起来。关于目标（2）和（3），这项工作有可能揭示核相关微管在植物微管生长和起始中的重要性。 其鉴定为微管组织中心（MTOC）细胞生物学。植物的微管已被证明对植物细胞的形状和大小有巨大的影响。与质膜相关的皮质阵列有助于确定细胞延伸的轴，而与细胞分裂平面相关的阵列有助于确定植物组织的形态发生。这些现象是利用植物、动物和真菌细胞骨架组装之间的差异生产有效的选择性除草剂的基础。这里提出的工作将为控制细胞骨架组装的植物特有的机制提供更多的见解。 此外，通过对细胞骨架参与植物花粉形成性质的分析获得的见解将从根本上有助于我们对植物繁殖的了解。 ***;