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Abstract

Determining the mechanisms that establish shape and identity in organs has
long been a goal for developmental biology. In plants, while many gains have
been made uncovering the genetic pathways that specify organ identity, little
is known about the downstream processes that actually regulate morphology
and cell type. Work focusing on the development of the Arabidopsis
fruit, however, has begun to elucidate some of these processes. The fruit is
composed of three domains, the valves, or seed pod walls, the replum which
develops in between the two valves, and the valve margin which develops
at the valve/replum border. Seed dispersal is promoted by the valve margin,
which undergoes a process of cell-cell separation that facilitates the detachment
of the valves from the replum. Valve margin formation is dependent
on the activation of the valve margin identity genes, SHATTERPROOF1,2,
ALCATRAZ and INDEHISCENT. In addition, the restricted activation of these
identity genes to the valve margin is controlled by the repressive activities
of FRUITFULL in the valves and REPLUMLESS in the replum. (See poster
by Roeder et al.) While much work has been done defining the regulatory
network that controls the definition of the valve margin, very little is known
about the mechanisms which establish this network. We will present work
that uncovers new layers of regulation controlling the development of the fruit
which unites genetic pathways that control lateral organ shape and polarity
with those that control valve margin identity.