Time-lapse imaging of the initiation of pollen embryogenesis in barley (Hordeum vulgare L.)

Pollen embryogenesis provides exciting opportunities in the areas of breeding and biotechnology as well as representing a convenient model for studying the process of plant cell proliferation in general and embryogenesis in particular. A cell culture system was devised in which immature barley pollen could be cultured as a monolayer trapped between the bottom glass-cover slip of a live-cell chamber and a diaphanous PTFE membrane within a liquid medium over a period of up to 28 d, allowing the process of embryogenesis to be tracked in individual pollen. Z-stacks of images were automatically captured every 3min, starting from the unicellular pollen stage up to the development of multicellular, embryogenic structures. The method should prove useful for the elucidation of ultrastructural features and molecular processes associated with pollen embryogenesis.