Electrical network activity in plant roots under gravity-changing conditions.

The MEA (multi-electrode array) system was used on maize roots during an ESA parabolic flight campaign in order to examine synchronized electrical activities under temporary changes of gravity conditions. As no previous data on the use of MEA system in microgravity conditions have been ever reported in literature, one of the main goals was to check the capability of the system to optimally perform continuous monitoring of root electrical activity. Results showed a clear overall root electrical activity, with differences in rates observed both during the same flight and among different ones. Moreover, the electrical activity (namely spike rate) tended to be significant lower in microgravity in comparison with the normal conditions, while hyper-gravity conditions seemed to be less effective in decreasing the spike rate. Hypergravity confirmed to cause an increase in the spike rate respect to both micro- and normogravity, which gave the lower spike rate. As a conclusion, the trial was successful, with gravity changes proving to affect spike rate generated by maize root tips.