Proc. Natl Acad. Sci. USA http://doi.org/bmjn (2016)

Soon after plants colonized the land half a billion years ago, they developed stomata to facilitate gas exchange with their new environment. Much later, grasses branched out and successfully adapted to different environments. Grass stomata are unique: linearly aligned, with dumbbell-shaped guard cells, and more efficient. Raissig, Abrash and colleagues from Stanford University, USA, focused on the transcription factors involved in stomatal development in the model grass Brachypodium distachyon, and compared them with their better-known Arabidopsis orthologues.

Using an unbiased forward genetic screen to identify mutants lacking stomata, and reverse genetics with CRISPR-induced mutations, the authors identify and characterize a series of transcription factors involved in stomatal development in Brachypodium. Curiously, Arabidopsis and Brachypodium use orthologues in the same general developmental processes, but they are differently ‘wired’, with distinct functions and post-translational regulation.

Stomatal development has become a model for studying postembryonic lineage, asymmetric divisions and cell fate in plants. The accumulated knowledge of this gene regulatory network, central to the evolutionary success of grasses, could now be used for targeted approaches to increase crop productivity through more efficient stomata.