The evolutionary origin of pollen formation (ePOLL)

ePOLL challenges the hypothesis that tapetum-dependent pollen formation in seed plants represents a heritage from the sporulation process in ancestral land plants habitating earth some 500 million years ago.

This hypothesis will be addressed through functional studies of a model moss representing a living relic of ancestral land plants by exhibiting sporulation seemingly dependent on tapetal-like somatic cells.

During the four year project period we will use methods with the highest possible spatiotemporal resolution to map the mechanisms for cell specification, function and communication underlying the nursing of sporogenous cells by tapetal-like cells in this moss.

Key methods include cell type-specific knockouts and transcriptomics, phenotypic analysis by transmission electron microscopy, and advanced fluorescence microscopy to demonstrate the intercellular movement of small regulatory RNAs and to reveal expression patterns in various reporter lines. ePOLL will generate fundamental knowledge about sporulation in mosses and ancestral land plants. ePOLL will also shed light on the evolutionary origin of the mechanisms underlying tapetum-dependent pollen formation in seed plants.

Finally, ePOLL may reveal novel mechanisms for somatic cell-nursing of pre- and post-meiotic cells of relevance for all land plants, including important crop and tree species.