Growing with the flow: how auxin transport helps to shape the growth and development of liverworts

Tom Fisher, Eduardo Flores-Sandoval, John Bowman

All land plants rely on the hormone auxin to control their development. All of these plants also rely on the auxin transport protein PIN-FORMED (PIN) to control the flow of auxin and thereby shape their growth. In flowering plants PINs have been intensively studied and are known to be important for many processes such as root gravitropism, shoot phototropism, the spiral arrangement of leaves and the initiation of flowers. In contrast, liverworts don’t have flowers, or leaves, or even roots, and yet in these distantly related plants the PIN protein remains highly conserved. So what is the role of PIN in liverworts? Using evidence from pin mutants, chemical treatments and fluorescently tagged PIN proteins we explored the function of MpPIN1 in the liverwort Marchantia polymorpha. Key findings: MpPIN1 is required to establish gemmae polarity and also to provide tropic growth in gametophore stalks, but, much like in flowering plants, MpPIN1 is dynamic and influences development in numerous ways across the life cycle of Marchantia polymorpha. On an evolutionary scale these findings reinforce that auxin flow from PINs is fundamental to plant development as a flexible mechanism to pattern growth.

Presenting Author:  Tom Fisher

Author Affiliation: Monash University