Dissertation Research: Endosperm Development, Embryology, and Gametic Fusion in Basal Angiosperms

9701210弗里德曼研究生桑德拉·弗洛伊德在科罗拉多大学威廉·弗里德曼博士的指导下，对几种可能是原始开花植物的植物胚胎的解剖学和发育进行了深入研究，以记录导致双受精和这些古代被子植物样本中胚乳形成(通常是三倍体)的细胞学事件。开花植物或被子植物与其他维管植物和种子植物的区别在于一系列看似独特的受精事件，导致植物胚胎与周围称为胚乳的营养组织形成。弗里德曼博士的开创性显微研究使用了强大的显微荧光分光光度测量细胞中的DNA含量，也证明了Gnetales目特殊裸子植物在种子发育过程中发生了类似的事件。弗洛伊德正在将研究项目扩展到被子植物的基本谱系，以探索早期被子植物胚胎进化所涉及的解剖学和发育的细胞细节。被子植物原始类群胚胎发育的精细形态或超微结构特征有望帮助解决开花植物早期谱系之间的系统发育关系，鉴于许多此类植物积累的DNA序列数据，这个问题仍未得到回答。获得这类研究所需的专门设备和技能是这项博士论文改进拨款的重要属性。

9701210 Friedman Graduate student Sandra Floyd, under the direction of advisor Dr. William Friedman at the University of Colorado, is conducting intensive studies of the anatomy and development of plant embryos in several species of putatively primitive flowering plants, to document cellular events leading to double fertilization and the formation of (usually triploid) endosperm in these exemplars of ancient angiosperms. Flowering plants, or angiosperms, are distinguished from other vascular and seed plants by a series of seemingly unique fertilization events, leading to the formation of the plant embryo with surrounding nutrient tissue called endosperm. Pioneering microscopic research by Dr. Friedman, using powerful microspectrofluorometric measurements of DNA content in cells, has demonstrated similar events in seed development in the peculiar gymnosperms of the order Gnetales. Ms. Floyd is extending the research program to basal lineages of angiosperms, to explore the cellular details of anatomy and development involved in the evolution of early angiosperm embryos. Fine-scale morphological or ultrastructural characters of embryo development in primitive groups of angiosperms hold promise of helping to resolve the phylogenetic relationships among early lineages of flowering plants, a question still unanswered in light of DNA sequence data accumulating for many of these plants. Access to the specialized equipment and skills needed for this kind of research are significant attributes of this doctoral dissertation improvement grant.