Edinburgh, Scotland, United Kingdom - TAIR

Evolution of patterning genes in land plants L06
Wednesday 12:00 - 12:30
Development
As more plant genome sequences become available, researchers are
increasingly using comparative genomics to address some of the major
questions in plant biology. Such questions include the evolution of
photosynthesis and multicellularity, and the developmental genetic changes
responsible for changes in body plan and the origin of important plant innovations
such as roots, leaves, and vascular tissue. We have focused on tracing the
evolutionary history of genes involved in pattern formation. In particular, we have
investigated the history of genes involved in establishing leaf polarity in
Arabidopsis. We find that some genes are evolutionarily recent, evolving
coincident with the evolution of leaves in seed plants. However, other genes
predate the evolution of leaves, implying a co-option from a more ancestral role.
Expression and functional studies in early diverging lineages of land plants
provide clues as to ancestral functions, and thus to the evolution of land plant
morphology. For example, Class III HD-Zip genes act to promote meristem
development, adaxial leaf development and vascular development in
Arabidopsis. Since the latter two tissues do not exist in early diverging land plant
lineages, apical growth and meristem development may represent an ancestral
function. Expression analyses in moss and liverworts support this hypothesis, but
also suggest a more direct role in response to light, an environmental parameter
that is key in molding the plastic development of plants, and establishing polarity
in liverworts in particular. Thus, ancestral roles of patterning genes may lie in
interactions with environmental parameters critical in the transition from an
aquatic algal ancestor to a land plant.
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John Bowman1,2
Sandra Floyd1
Keiko Sakakibara1
Karen Yip2
Chris Zalewski2
Eduardo Flores1
Pia Sappl1
John Alvarez1
Dyani Lewis1
1Monash University,
Melbourne
Victoria
Australia
2UC Davis
Davis
CA
USA