Exploring the physiological and biochemical changes in tomato (Lycopersicon esculentum Mill.) under salt stress and recovery: role of antioxidant defense and glyoxalase system for attuning salinity tolerance

Parvin K1,2, Bhuyan MHMB1,3, Hasanuzzaman M4, Nahar K5, Mohsin SM1,6, Hossain MS1 and Fujita M1

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

Both stress and consequent episodes are highly sensitive to plant growth, physiological and biochemical processes. Hereafter, we investigated the plant responses to salinity and recovery process to find out the salt tolerance mechanism in tomato focusing the antioxidant defense mechanism and glyoxalase system. Hydroponically grown 16-d-old tomato seedlings (Lycopersicon esculentum Mill. cv. Pusa ruby) were treated with 150 and 250 mM NaCl for 4 days, and subsequently grown 2 days in salt free condition in order to observe post stress revival. Under saline condition, plants suffered from acute osmotic stress associated with lower relative water content (RWC) of leaf tissues, destruction of photosynthetic pigments, and higher proline content in a dose dependent manner. Henceforth, salinity induced oxidative stress through overproduction of reactive oxygen species (H2O2 and O2•–), and methylglyoxal (MG); eventually damage the membranes (higher electrolyte leakage), and lipids (elevated malondialdehyde). Salinity also impaired the non enzymatic and enzymatic components of antioxidant defense system and disrupted redox balance. As a result the growth and development of tomato seedlings stagnated. But when the seedlings were allowed to grow in the saline free condition; a dramatic change was visible in the seedlings, and within 2-day of recovery, improved plant growth, water balance and chlorophyll synthesis was observed followed by restoration of the activity of antioxidant defense as well as glyoxalase systems, which scavenge the toxic ROS and lowered the lipid peroxidation and membrane damage. Thus, our result suggested that tomato plant can tolerate salinity, and can undergo a quick post stress recovery by enhancing antioxidant defense mechanism and glyoxalase pathway.