Polarity proteins shape efficient 'breathing' pores in grasses

For the current study, Prof. Dr. Michael Raissig, Dr. Heike Lindner and co-author Roxane Spiegelhalder from the Institute of Plant Sciences (IPS) at the University of Bern investigated the development of helper in the Brachypodium distachyon. They discovered two proteins that accumulate on opposite sides of a cell, acting like a "compass" to ensure the correct development of helper cells in grasses. The research results were published in the journal eLife.

A cell compass for the development of helper cells

Helper cells are formed by unequal, . In this process, a cell divides into a small cell, the helper cell, and a larger neighboring cell. For this division to occur in the correct ratio and orientation, the cell needs landmarks. These landmarks act as points of orientation and are given by so-called polarity proteins, which accumulate on opposite sides of the cell and can thus define, for example, left and right or top and bottom.

One of the two “compass proteins” (POLAR, in pink) orients the future cell division. In gray are cell outlines on the developing leaf. Credit: Michael T. Raissig

A grass “breathing pore” consists of two central, dumbbell-shaped guard cells and two lateral helper cells. Credit: Michael T. Raissig

The wild model grass Brachypodium distachyon. Credit: Michael T. Raissig