The dynamics of touch-responsive gene expression in cereals.

Wind, rain, herbivores, obstacles, neighbouring plants, etc. provide important mechanical cues to steer plant growth and survival. Mechanostimulation to stimulate yield and stress resistance of crops is of significant research interest, yet a molecular understanding of transcriptional responses to touch is largely absent in cereals. To address this, we performed whole-genome transcriptomics following mechano-stimulation of wheat, barley and the recently genome-sequenced oat. The largest transcriptome changes occurred ±25 min after touching, with the majority of genes being upregulated. While most genes returned to basal expression level by 1-2h in oat, many genes retained high expression even 4 h post-treatment in barley and wheat. Functional categories like transcription factors, kinases, phytohormones and Ca 2+ -regulation were affected. Also cell wall-related genes involved in (hemi)cellulose, lignin, suberin and callose biosynthesis were touch-responsive, providing molecular insight into mechanically-induced changes in cell wall composition. Furthermore, several cereal-specific transcriptomic footprints were identified that were not observed in Arabidopsis. In oat and barley, we found evidence for systemic spreading of touch-induced signalling. Finally, we provide evidence that both jasmonic acid (JA)-dependent and JA-independent pathways underlie touch-signalling in cereals, providing a detailed framework and marker genes for further study of (a)biotic stress responses in cereals.