No abstract

Microgravity is one of the most important abiotic stresses in space. In the case of plant exposure to short term microgravity, plants establish strategies to response to these stresses and promote growth and survival. We hypothesized that the simulated microgravity can promote the antioxidant capacity and the formation of secondary metabolites such as tropane alkaloids in the Hyoscyamus niger. Callus induction was conducted by putting hypocotyl segments of H. niger seedlings in solid MS medium supplemented with 1 mg L−1 2,4-D and 1 mg L−1 BAP growth regulators. Then, the sub-cultured calli were placed on a clinostat for 3, 7 and 10 days. We performed Atropine and Scopolamine determination through HPLC. PAL (Phenyle alanine amonalyase) and antioxidant activity were also determined. Gene expression analysis of jasmonic acid (JA), Hyoscyamine 6-beta Hydroxylase (H6H), Putrescine N-methyltransferase (PMT), mitogen-activated protein kinase (MAPK) and ethylene responsive element binding (EREB) was performed using quantitative real time PCR. Findings showed that microgravity had a positive effect on the antioxidant capacity, Atropine and Scopolamine production in the H. niger calli. However, microgravity had a negative effect on the PAL activity. Furthermore, gene expression analysis indicated that microgravity significantly induced gene expression of the H6H, PMT and JA. It was also revealed that callus growth, carbohydrate and protein content increased in response to microgravity treatment. We conclude that microgravity can be considered as a potent factor to induce plant antioxidant activity and tropane alkaloids formation to be applicable in the pharmaceutical and medicinal industries.