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Research

 
 
 
 
 
In our research group, we are using the model organism Arabidopsis thaliana to study molecular signaling pathways
that guide the early embryonic patterning process.
 
 

After fertilization, the zygote elongates about 3-fold before it divides asymmetrically giving rise to a smaller apical and a larger basal cell. The smaller apical cell will form the embryo while the basal daughter cell gives rise to a filamentous, mainly extra-embryonic structure - the suspensor.

Our main research questions

 
 

- How does the egg cell recognize that fertilization occurred and how is embryogenesis initiated on the molecular level?
 
 
 
- What intrinsic or external signals polarize the zygote and lead to the first asymmetric cell division?
 
 
 
- How are embryonic and extra-embryonic differentiation regulated in the daughter cells of the first division?
 
 
 
- What gene expression determines suspensor cell-identity, physiology, and function

The embryonic YODA pathway

Zygote elongation and suspensor development are influenced by a MAP kinase signaling pathway including the MAPKKK YODA (YDA). This pathway appears to be a potent regulator of suspensor formation, since yda loss-of-function mutants lack a recognizable suspensor structure while constitutively-active versions of YDA can transform the whole embryo into suspensor-like cells.
 
Little is known about this embryonic YODA signaling pathway on the molecular level.
Recently, we described a gene for the sperm-specific receptor-like cytoplasmic kinase SHORT SUSPENSOR (SSP) that controls the elongation of the zygote and suspensor formation through an unusual parent-of-origin effect. Our data suggests that SSP mRNA is accumulating specifically in sperm-cells of mature pollen and is delivered to the zygote during fertilization. Translation of these inherited transcripts leads to transient accumulation of SSP protein in the zygote where it participates in YODA activation.
 
 

Simplified model of the embryonic YODA signaling pathway