**Early Cellular Responses Induced by Sedimentary Calcite-Processed Particles in Bright Yellow 2 Tobacco Cultured Cells**

**Daniel Tran 1,2,\*, Tingting Zhao 2, Delphine Arbelet-Bonnin 2,3, Takashi Kadono 2,4, Patrice Meimoun 2, Sylvie Cangémi 2, Tomonori Kawano 4,5,6,7, Rafik Errakhi 8 and François Bouteau 2,3,5,6**


Received: 24 April 2020; Accepted: 12 June 2020; Published: 16 June 2020

**Abstract:** Calcite processed particles (CaPPs, Megagreen®) elaborated from sedimentary limestone rock, and finned by tribomecanic process were found to increase photosynthetic CO2 fixation grapevines and stimulate growth of various cultured plants. Due to their processing, the CaPPs present a jagged shape with some invaginations below the micrometer size. We hypothesised that CaPPs could have a nanoparticle (NP)-like effects on plants. Our data show that CaPPs spontaneously induced reactive oxygen species (ROS) in liquid medium. These ROS could in turn induce well-known cellular events such as increase in cytosolic Ca2+, biotic ROS generation and activation of anion channels indicating that these CaPPs could activate various signalling pathways in a NP-like manner.

**Keywords:** tobacco; calcium; calcite; reactive oxygen species; ion channels; cellular signalization
