News aus der Fakultät

29.11.2011

Kiyotaka Okada, National Institute for Basic Biology, Okazaki, Japan

Monday, 5 December 13:00, Hörsaal N11, Auf der Morgenstelle 3

How to make up leaf faces:

The adaxial-abaxial polarity-dependent development of leaves

Kiyotaka Okada (National Institute for Basic Biology, Okazaki, Japan)

Abstract

Leaves develop tissue layers with cells of unique form and function along the adaxial-abaxial axis. In order to examine molecular process which establishes the ad-ab axis in leaf primordia and differentiates region-specific cells, we isolated and characterized mutants with altered formation of the abaxial and adaxial domains. One mutant, enf1 (enlarged FIL-expression domain) forms leaves with enlarged and reduced abaxial domain, and sometimes leaves of filamentous structure. ENF1 gene encodes SUCCINIC SEMIALDEHYDE DEHYDROGENASE (SSADH), which catalyzes the conversion of succinic semialdehyde (SSA) to succinate. Exogenous application of SSA induced additional adaxial characters on the newly developed leaves. Further analyses of gene expression pattern and suppressor lines strongly suggested that SSA or its close derivatives provides adaxial nature to leaf primordia.

After established the ad-ab axis, leaf primordia develop leaf blade along the medial-lateral axis, and form margin-specific cells. Our recent examination of a double mutant lacking two WUSCHEL-RELATED HOMEOBOX (WOX) genes, PRS and WOX1, encoding homeobox transcription factors, proposed presence and role of the third domain between the adaxial and the abaxial domains. Formation of the “middle domain” is required for blade growth and margin development.

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Gerd Jürgens

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