The Occurrence and Role of Substrate Adhesion Molecules (SAMs) in Plants

底物粘附分子（sam）是一类存在于多种生物细胞外基质（ECM）中的粘附糖蛋白。玻璃体连接蛋白（VN）是一种与细胞粘附和迁移有关的SAM。PI已经确定，在植物的原代细胞壁中存在与VN的同源物，并有证据表明其在花柱中促进花粉管延伸的作用。本研究旨在从多个角度了解植物生长发育过程中玻璃体连接蛋白样分子的表达、定位和功能。提出的实验将专门测试VN样分子在授粉过程中的作用。免疫细胞化学和荧光染色技术将用于检查花粉管伸长和芽形成过程中细胞骨架成分、VN样分子和VN受体（整合素）之间的关系。已知介导VN与其整合素粘附的合成肽将用于确定其在体内和体外对花粉管伸长的影响。编码vn样蛋白的cDNA克隆将被分离和表征。在植物发育过程中，VN RNA的水平将通过RNA印迹和原位杂交来检测。VN样蛋白在植物发育过程中的作用将通过在转基因植物中使用嵌合基因构建过表达和低表达VN rna来测试。

Substrate adhesion molecules (SAMs) belong to a family of adhesive glycoproteins which occur in the extracellular matrix (ECM) of a variety of organisms. Vitronectin (VN) is a SAM that has been implicated in cell adhesion and migration. The PI's have established that a homolog to VN occurs in the primary cell wall of plants, and have evidence for its role in facilitating pollen tube extension in the style. The proposed research is a multi- faceted approach to understanding the expression, localization, and function of vitronectin-like molecules during plant development. The experiments proposed will specifically test the role of VN- like molecules during pollination. Immunocytochemical and fluorescence staining techniques will be used to examine the relationship between components of the cytoskeleton, VN-like molecules, and VN receptors (integrins) during pollen tube elongation and during shoot ontogeny. Synthetic peptides that are known to mediate adhesion of VN to its integrin will be used to determine their effect on pollen tube elongation in vivo and in vitro. cDNA clones that encode VN-like proteins will be isolated and characterized. The levels of VN RNA during plant development will be examined by RNA blot and in situ hybridizations. The role of VN-like proteins during plant development will be tested by overexpressing and underexpressing VN RNAs using chimeric gene constructs in transgenic plants.