Kužela seminar series

Fri 9 Mar. 2012, 14:00
CH1-222

Title: A key step in land plant evolution and function: Genetic control of the development of 3D body plan in higher plants
Speaker: Odd-Arne Olsen, Norwegian University of Life Sciences, Ås & Hedmark University College, Hamar, Norway

Land plants evolved during the last billions years or so from single celled
green algae, a transition that required the ability to regulate
growth in three, rather than two dimensions. Our project focuses
on the evolution and function of the DEK1 protein encoding a membrane
anchored calpain proteinase that functions in higher plants to orient
and direct three dimensional growth. We trace the origin of DEK1 to a fusion
between genes encoding a membrane protein and a calpain 1.5 billion years ago.
Unlike other organisms, plants only have one calpain gene that is highly
conserved from Mesostigma viridis, a single celled green algae,
to Arabidopsis thaliana, a modern dicot plant. Our working hypothesis
is that DEK1, in interaction with other proteins, enabled the evolution
of meristems, and thereby higher plants, by defining the epidermal cell (L1)
position. In addition to meristems, DEK1 is essential for epidermal cell
development, and thus proper differentiation of embryos, endosperm and leaves.
Support for the function of DEK1 in meristems comes from the moss
Physcomitrella patens, in which a deletion of the DEK1 gene permits two
dimensional growth of protonemal cells, but arrest gametophore development
already after the first division of bud apical cell. This project focuses
on the evolution of the DEK1 in the plant lineage, including the mechanism
for interpreting positional information, mechanisms of DEK1 activation,
substrate recognition and processing. A special emphasis will be placed
on understanding the evolution of the network of interactors that enabled
mersitem functionality.