Mechanical control of germ cell specification in Arabidopsis anthers

A central question in developmental biology is how the germline is established. We have studied the specification of the male germ cells (GCs) within the anther ^1–3 . Hereby, we have focused on the potential role of mechanics, an aspect of anther development which has been very poorly characterized ^2,4 . Using a combination of live imaging and mechanical measurements, we provide evidence that GCs originate in a special micro-mechanical niche, where inner tissues exert ‘push’ on outer cell layers, placing them under compression. Mechanical perturbations significantly disrupted the GC specification and patterning. Moreover, we found that the master genetic regulator SPOROCYTELESS/NOZZLE (SPL/NZZ) ^5,6 is central in establishing this micro-mechanical environment by softening the cell wall. The mechanical cues, in turn, stabilize the transcription of SPL/NZZ . We propose here an intrinsic growth-derived mechano-chemical feedback loop that drives germ-cell fate acquisition.