Flowers and mycorrhizal roots – closer than we think?

• Surprising overlaps between root symbiosis and pollen development.
• Genetic and transcriptomic overlaps between arbuscular mycorrhiza and pollen development.
• Lipid polyester pathway is involved in arbuscular mycorrhiza and pollen development.

Roots and flowers are formed at the extreme ends of plants and they differ in almost every aspect of their development and function; even so, they exhibit surprising molecular commonalities. For example, the calcium and calmodulin-dependent protein kinase (CCaMK) plays a central role in root symbioses with fungi and bacteria, but is also highly expressed in developing anthers. Moreover, independent evidence from transcriptomics, phylogenomics, and genetics reveals common developmental elements in root symbioses and reproductive development. We discuss the significance of these overlaps, and we argue that an integrated comparative view of the two phenomena will stimulate research and provide new insight, not only into shared components, but also into the specific aspects of anther development and root symbioses.