Abstract text: The plant cell wall integrity (CWI) monitoring system must balance growth with defence by tuning the plant’s response to wall perturbation. Our research focuses on two transcription factors – ZINC FINGER OF ARABIDOPSIS THALIANA 11 (ZAT11) and ZAT18 – which belong to the ZAT gene cluster and are among the fastest, most specific responders to CWI disruption.

We tested how ZAT11 and ZAT18 perturbations affect THE1 transcriptional responses in a CWI-relevant treatment series, including cell wall stress induced by isoxaben (ISX) and/or sorbitol. We then investigated whether these transcriptional differences are accompanied by measurable changes in the wall. Functional analyses show that ISX leads to shifts in cell wall composition of ZAT mutants, accompanied by changes in wall stiffness. These mechanical phenotypes differ across ZAT genotypes, linking ZAT function to biophysical wall properties.

Our results indicate that ZAT11 and ZAT18 act together in the control of THE1 inducibility, positioning them as key fine-tuners of early CWI activation. This leads to a key question: since CWI is “always on” and constantly sensing the wall, how does the plant avoid overreacting, while still distinguishing mild stress – where growth should continue – from more severe wall damage that requires a stronger response?