Silicon-induced antioxidant defense, methylglyoxal detoxification and metal chelation works coordinately in alleviating nickel toxicity in Oryza sativa L.

Mohsin SM1,2, Hasanuzzaman M3, Alam MM4, Nahar K5, Bhuyan MHMB1,6, Parvin K1,7 and Fujita M1

  1. Laboratory of Plant Stress Responses, Department of Applied Biological Sciences, Faculty of Agriculture, Kagawa University, Miki-Cho, Kita-Gun, Kagawa 761-0795, Japan.
  2. Department of Plant Pathology, Faculty of Agriculture, Sher-e-Bangla Agricultural University, Sher-e-Bangla Nagar, Dhaka-1207, Bangladesh.
  3. Department of Agronomy, Faculty of Agriculture, Sher-e-Bangla Agricultural University, Sher-e-Bangla Nagar, Dhaka-1207, Bangladesh.
  4. Department of Agriculture, Faculty of Science, Noakhali Science and Technology University, Noakhali-3814, Bangladesh.
  5. Department of Agricultural Botany, Faculty of Agriculture, Sher-e-Bangla Agricultural University, Sher-e-Bangla Nagar, Dhaka-1207, Bangladesh.
  6. Bangladesh Agricultural Research Institute, Joydebpur, Gazipur-1701, Bangladesh.
  7. Department of Horticulture, Faculty of Agriculture, Sher-e-Bangla Agricultural University, Sher-e-Bangla Nagar, Dhaka-1207, Bangladesh.

Nickel (Ni) is an essential plant nutrient but very toxic to plant at supra-optimal concentration and causes inhibition of seed germination, growth, and development of plants. The present study investigates the possible mechanisms of Ni tolerance in rice seedlings by exogenous application of silicon (Si). Hydroponically grown 13-day-old rice (Oryza sativa L. cv. BRRI dhan54) seedlings were exposed to 0.25 mM and 0.5 mM NiSO4 alone and combined with 0.50 mM Na2SiO3 for 3 days to investigate the effect of Ni toxicity as well as the role of Si revoking the stress. Nickel toxicity caused oxidative stress by overproduction of reactive oxygen species (ROS) and methylglyoxal (MG) in seedlings of rice that created higher lipid peroxidation and membrane damage. Nickel stress also reduced growth and biomass, leaf relative water content (RWC), and chlorophyll (chl) content of seedlings. However, non-protein thiol (NPT) content, phytochelatin (PC) and proline (Pro) content increased in Ni-stress. In contrast, the Ni-stressed seedlings supplemented with exogenous Si recovered from water loss, chlorosis, growth inhibition, and oxidative stress. Silicon up-regulated most of the antioxidant defense components as well as glyoxalase systems, which helped to improve ROS and MG detoxification respectively. Hence, these findings suggest that the exogenous application of Si can improve the tolerance of rice seedlings to Ni-toxicity.