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Plant early embryogenesis

Gerd Jürgens

Gerd Jürgens

  • PhD in Zoology, University of Freiburg, 1977
  • Postdoctoral training at the EMBL, Heidelberg, 1980-81
  • Professor of Developmental Genetics, University of Tübingen since 1994
  • Director at the MPI since 2008

Research Interest

Our research addresses molecular mechanisms of plant development, focusing on apical-basal patterning in early embryogenesis of Arabidopsis. Mutant screens have identified key regulators of apical-basal patterning, such as proteins involved in transport of the signaling molecule auxin or in the gene-regulatory response to auxin. We are currently analyzing how the identified players mediate apical-basal patterning. The auxin-response transcription factor MP (= ARF5) is inhibited by the Aux/IAA protein BDL (= IAA12) until BDL is degraded in response to an elevated auxin level. Both proteins are only expressed and act in the apical lineage, but indirectly bring about auxin accumulation in the uppermost cell of the basal lineage, the prospective hypophysis, by influencing localization of the auxin-efflux regulator PIN1. 

However, auxin alone does not seem to be sufficient. A differential screen for additional targets of MP and BDL by genome-wide expression profiling has identified transcription factors that act downstream of MP in early embryogenesis. A cis-regulatory element that mediates BDL gene expression has been used to search for trans-regulatory factors. Surprisingly, MP activates the expression of BDL as well as its own, whereas BDL provides a negative feedback loop, thus creating a molecular switch triggered by rising auxin levels during embryogenesis. 

Selected Reading

1) Takada S, Jürgens G. (2007) Transcriptional regulation of epidermal cell fate in the Arabidopsis embryo. Development 134, 1141-50.

2) Schlereth A, Möller B, Liu W, Kientz M, Flipse J, et al. (2010) MONOPTEROS controls embryonic root initiation by regulating a mobile transcription factor. Nature 464, 913-6.

3) Lau S, De Smet I, Kolb M, Meinhardt H, Jürgens G. (2011). Auxin triggers a genetic switch. Nature Cell Biol 13, 611-5.
(click to enlarge)
Fluorescent nuclear markers highlighting (A) the basal cell lineage, (B) the apical cell lineage and (C) the entire young embryo plus suspensor. The arrowheads mark the boundary between the apical (embryonic) lineage and the basal (extra-embryonic) lineage.
(click to enlarge)
Diagram depicting the changing spatial distribution of the signaling molecule auxin as visualised by the DR5 auxin-response GFP reporter (green), the localisation of auxin-efflux transporters (PIN1, orange; PIN7, red) and the expression of auxin response regulators (MP, BDL; nuclei indicated). (A-E) Stages of embryogenesis: (A) one-cell, (B) eight-cell, (C) dermatogen, (D) early-globular, (E) mid-globular.