Following the Time-Course of Post-pollination Events by Transmission Electron Microscopy (TEM): Buildup of Exosome-Like Structures with Compatible Pollinations.

In the Brassicaceae, the dry stigma is an initial barrier to pollen acceptance as the stigmatic papillae lack surface secretions, and consequently rapid cellular responses are required to accept compatible pollen. Regulated secretion with secretory vesicles or multivesicular bodies is initiated in the stigmatic papillae towards the compatible pollen grain. In self-incompatible species, this basal compatible pollen response is superseded by the self-incompatibility signaling pathway where the secretory organelles are found in autophagosomes and vacuole for destruction. In this chapter, we describe a detailed protocol using the Transmission Electron Microscope to document the rapid cellular changes that occur in the stigmatic papillae in response to compatible versus self-incompatible pollen, at the pollen-stigma interface.