Biological Sciences

Events and seminars

Monday Seminar Series - "Making a flat leaf: Pre-patterning, morphogenic small RNAs, and Turing dynamics"

Prof Dr Marja Timmermans - Center for Plant Molecular Biology, University of Tuebingen

18th March 2024 at 12:00pm [Download iCalendar / .ics file]

Daniel Rutherford, G.27, LT1

Emanuele Scacchi1, Gael Paszkiewicz1, Agata Burian2, Khoa Nguyen1, Shreyas Meda1, and Marja Timmermans1

 

1) Center for Plant Molecular Biology, University of Tuebingen, Auf der Morgenstelle 32, 72076 Tuebingen, Germany

2) University of Silesia in Katowice, Jagiellonska 28, 40-032 Katowice, Poland

 

As the principal photosynthetic organ, a leaf commonly develops as a thin, flat lamina optimized for light capture and gas exchange. The flat geometry appears deceptively simple. In reality, its production poses an unusual and mechanistically challenging problem; namely, how to create a stable adaxial-abaxial (top-bottom) boundary within the plane of a long and wide, but shallow, structure that grows orders of magnitude in size. By combining time-lapse confocal imaging, cell lineage tracing and molecular genetic analyses, we have shown that adaxial-abaxial polarity is specified by a pre-pattern at the shoot stem cell niche. This pre-pattern converts a uniform signaling input from the organogenic hormone auxin into a ARF-dependent binary response output to distinguish adaxial from abaxial identity. As the leaf primordium emerges from the pre-patterned niche environment, polarity is regulated by an intricate network of transcription factor and small RNA interactions. The latter provide positional information, and like classical morphogens generate sharply defined domains of target gene expression through an intrinsic threshold-based readout of their mobility gradients. Finally, our most recent findings show that this gene regulatory network follows the organizing principles of a Turing system. Adaxial-abaxial polarity is thus propagated by a self-organizing system of small RNA - transcription factor interactions. This system dynamically adapts to internal and external perturbations to sustain a robust polarity boundary in planar leaves, but at the same time provides flexibility to support morphological diversity.

Host Catherine Kidner, IMPS

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