关键词：
Eumagnoliid
Saururaceae
Saururus cernuus
Self-incompatibility
摘要：
Mechanisms of self-incompatibility (SI) are quite diverse across flowering plant families, but little is known about SI in extant basal angiosperm groups regarding the site, timing and mechanistic aspects of self rejection. This dissertation examines the spatial and temporal features of SI, the cell biology of SI and the role of SI in natural populations of Saururus cernuus L. (“Lizard's Tail”), an herbaceous eumagnoliid belonging to the Saururaceae, a family that exhibits high rates of self-sterility due to SI in three of five taxa. Self rejection in S. cernuus occurs on a dry type stigma and prevents the proper adhesion and hydration of incompatible pollen grains. With the use of cryofixation/freeze-substitution electron microscopy, stereological cell quantification methods and immunolocalization studies with various antibody probes for vesicle trafficking within the endomembrane system, it was demonstrated that self pollination results in the rapid stimulation of clathrin-mediated endocytotis (CME) and vesicle trafficking within endomembrane compartments important in intracellular sorting of molecular information along the endocytotic pathway. Concurrently, self pollination induces the expansion of a dynamic and heterogeneous microtubule-associated endomembrane network consisting of cisternal, branched tubular membranes and budding clathrin-coated pits/vesicles that are posited to be the plant-equivalent of an early endosome complex. Antibodies to Arabidopsis Ara6, a protein exhibiting homology of a mammalian Rab5-GTPase involved in homotypic early endosome fusion, colocalized to this heterogeneous endomembrane system, as did clathrin network machinery proteins (clathrin heavy chain, AtSH3P1 and auxilin-like protein) and the Arabidopsis t-SNARE, AtPEP12p. The functional significance of stimulated CME and endomembrane modifications of stigmatic cells during the SI response is unknown until the identity and sorting fate of the internalized cargo has been establishe
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