How can plants perceive mechanical stress such as touch? Calcium and several proteins are known to be involved, but it is still unclear how they interact. VIP1 of the model plant Arabidopsis thaliana is a bZIP (basic Leucine Zipper Domain) transcription factor and one of such proteins. When cells perceive mechanical stress, VIP1 moves from the cytosol to the nucleus, changes gene expression patterns, and regulates root bending, which helps roots avoid obstacles.
Tsugama et al. report that VIP1 binds to the calcium-binding calmodulin proteins, and that its nuclear-cytoplasmic shuttling requires calcium. This study can help find novel regulators of mechanical stress responses and fully answer the above question.
Tsugama, D., Liu, S., Fujino, K., & Takano, T. (2018). Calcium signalling regulates the functions of the bZIP protein VIP1 in touch responses in Arabidopsis thaliana. Annals of Botany, 122(7), 1219–1229. https://doi.org/10.1093/aob/mcy125