IBIP seminar

Thursday, November 8, 2018
Room 106 at 2:00 pm

Dehiscence zone as a developmental timer for explosive seed dispersal in Cardamine hirsuta

Galstyan Anahit
Max Planck Institute for Plant Breeding Research, Cologne, Nordrhein-Westfalen, Germany

Adaptations for dispersal are ubiquitous in nature and fruits play an important role in the seed dispersal of flowering plants. Seed dispersal occurs via a process called pod shatter in both explosive fruit of Cardamine hirsute and the non-explosive fruit of Arabidopsis thaliana, and relies on the precise patterning of fruit tissues during development. The dehiscence takes place by physical separation of specialized tissues at the valve margin in both species. In A. thaliana, this occurs as the fruit dries out, separating the valve from the replum and exposing seeds for dispersal. In contrast to this, seed dispersal by explosive pod shatter occurs before the fruit dries out in C. hirsute where established pretension and accumulation of elastic energy drive the explosive coiling of the vales.
This raises the hypothesis that the developmental control of dehiscence zone formation may trigger the process of explosive seed dispersal in C. hirsute. To test this hypothesis, we have performed comprehensive genetic analysis of fruit patterning genetic network in C. hirsute. Mutation in valve margin regulator INDEHISCENT (IND) abolishes dehiscence zone formation. In chind mutants, the energy required for explosion is trapped due to inability of valve tissue physically separate from the replum. We also found that in C.hirsuta the function of FRUITFULL (FUL) is conserved. FUL specified valve tissue by repression of valve margin genetic network and ful mutants exhibit homeotic conversion of valve into valve margin. However, unlike A. thaliana ful, where the ectopic valve margin identity consists mostly of lignified cells, the ectopic valve margin identity in C. hirsuta ful consists mostly of separation layer cells. Collectively, these results suggest that the genetic network controlling valve margin identity in C. hirsuta shows conservation with A. thaliana but has been re-wired to set separation layer as predominant valve margin fate.

Contact : Gabriel Krouk

Contacts IBIP :
Sabine Zimmermann
Alexandre Martinière
Florent Pantin
Chantal Baracco
Véronique Rafin