Silicon-mediated genotoxic alterations in Brassica juncea under arsenic stress: A comparative study of biochemical and molecular markers

Arsenic(As),one of the most harmful toxicant at the global level,severely affects plant metabolism when taken up.Interestingly,the presence of silicon(Si)as a fertilizer in As-contaminated soil is an effective strategy to decrease As accumulation in plants.Brassica juncea(var.Varuna)were grown hydroponically to investigate the role of Si at biochemical and molecular levels under arsenite(As3+)stress.Seedlings of B.juncea were exposed to As3+,Si,and a combination of both elements.Our data demonstrated that seedlings exposed to As3+showed an inhibition in shoot length,chlorophyll,carotenoid,and protein,while co-application of Si improved these growth parameters.Silicon supplementation reduced As accumulation in shoot.Increase/decrease was observed in stress-related parameters(cysteine and proline),antioxidant enzymes(superoxide dismutase,ascorbate peroxidase,and catalase),and oxidative stress markers(malondialdehyde and H2O2),which were improved upon co-application of Si as compared to As3+alone treatment.Random amplified polymorphic DNA(RAPD)is a suitable biomarker assay for plants for assessing the genotoxicity.Seven RAPD primers produced a total of 39 and 48 bands in the leaves of the untreated and treated seedlings,respectively.The RAPD band-profiles and genomic template stability were consistent with other growth and physiological parameters.In conclusion,the genotoxic alterations along with the biochemical parameters indicate that the exposure to Si mitigates As3+-induced oxidative stress by improving the stress-related parameters and antioxidant system in B.juncea.