Jérémy Gruel (Sainsbury Laboratory Cambridge University) is giving a common LJC-CBP seminar Wednesday 28th May at 11 am, in the big CBP room (LR6) :

Differentiation control in the Shoot Apical Meristem, an inside out model

The Shoot Apical Meristem (SAM) is a dome structure of a few thousand cells at the origin of all above ground plant organs. In the SAM, plant hormones, such as cytokinin, control a complex gene expression network tightly regulating the amount of stem cells as well as the differentiation of their descendants.

Even though the interactions between the various gene expression domains are getting better understood, they are not sufficient to maintain them correctly positioned in a three dimensional tissue. As of today, models have had to rely on hypothetical positional cues to help gene expression to the correct locations. Based on recent evidence, we show that a single positional cue, the external cell layer of the SAM, is enough to pattern the ensemble of the SAM domains.

The proposed model, in which tissue shape controls gene expression, is robust to cell division, growth and tissue deformation. It also offers a possible explanation to the emergence of new stem cell niches in growing primordia.