Effects of high-intensity static magnetic fields on a root-based bioreactor system for space applications

Static magnetic fields created by superconducting magnets have been proposed as an effective solution to protect spacecrafts and planetary stations from cosmic radiations. This shield can deflect high-energy particles exerting injurious effects on living organisms, including plants. In fact, plant systems are becoming increasingly interesting for space adaptation studies, being useful not only as food source but also as sink of bioactive molecules in future bioregenerative life-support systems (BLSS). However, the application of protective magnetic shields would generate inside space habitats residual magnetic fields, of the order of few hundreds milli Tesla, whose effect on plant systems is poorly known. To simulate the exposure conditions of these residual magnetic fields in shielded environment, devices generating high-intensity static magnetic field (SMF) were comparatively evaluated in blind exposure experiments (250 mT, 500 mT and sham -no SMF-). The effects of these SMFs were assayed on tomato cultures (hairy roots) previously engineered to produce anthocyanins, known for their anti-oxidant properties and possibly useful in the setting of BLSS. Hairy roots exposed for periods ranging from 24 h to 11 days were morphometrically analyzed to measure their growth and corresponding molecular changes were assessed by a differential proteomic approach. After disclosing blind exposure protocol, a stringent statistical elaboration revealed the absence of significant differences in the soluble proteome, perfectly matching phenotypic results. These experimental evidences demonstrate that the identified plant system well tolerates the exposure to these magnetic fields. Results hereby described reinforce the notion of using this plant organ culture as a tool in ground-based experiments simulating space and planetary environments, in a perspective of using tomato 'hairy root' cultures as bioreactor of ready-to-use bioactive molecules during future long-term space missions.