Abstract

The huge diversity of multicellular land plants we see on earth today evolved from a single, relatively simple, ancestor around 450 million years ago. Early-evolving land plants had to face specific challenges including desiccation and gravitational forces, and becoming multicellular was key for land plants to overcome these challenges and ultimately become such a successful lineage. To understand the molecular mechanisms enabling the transition to multicellularity in the plant lineage, the Coates lab uses molecular genetics to define the function of conserved proteins known to be involved in promoting multicellularity in animals, fungi and amoebae (unikonts). One example of such proteins is the Armadillo protein family, which plays fundamental roles in both cell differentiation and cell architecture/adhesion in unikonts. We have characterised Armadillo protein function both in a complex flowering plant, Arabidopsis thaliana, and in an early-evolving land plant, the moss Physcomitrella patens. We suggest that plant Armadillo proteins have conserved fundamental function(s) common to all land plants, including during responses to a hormone, Abscisic Acid (ABA), found in many kingdoms. In addition, plant Armadillo proteins have also acquired novel, ABA -independent developmental functions during the evolution of more complex body plans.