Seed priming with malic acid confers low pH stress tolerance to wheat (Triticum aestivum L.) seedlings by upregulating antioxidant defense and methylglyoxal detoxification system

Bhuyan MHMB1,2, Hasanuzzaman M3, Mahmud JA4, Hossain MS1, Hossen MS1,3, Masud AAC1,3 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. Bangladesh Agricultural Research Institute, Joydebpur, Gazipur-1701, Bangladesh.
  3. Department of Agronomy, Sher-e-Bangla Agricultural University, Sher-e-Bangla Nagar, Dhaka-1207, Bangladesh.
  4. Department of Agroforestry and Environmental Sciences, Sher-e-Bangla Agricultural University, Sher-e-Bangla Nagar, Dhaka-1207, Bangladesh.

Low soil pH causes from H+ rhizotoxicity, inhibits plant growth, development and reduces crop yields. Hence, the present study was carried out to reveal the possible mechanisms of acidity stress tolerance in wheat after seed priming with malic acid (MA). Hydroponically grown 8-day-old wheat seedlings (Triticum aestivum L. cv. BARI Gom-25) were exposed to acidic growing media (pH 4.0), alone and combined with 0.5 mM and 1.0 mM MA for 3 and 6 days in order to investigate the effect of acidity stress as well as role of MA counteracting the stress. Acidity (pH 4.0) created oxidative stress by the overproduction of reactive oxygen species (ROS) and methylglyoxal (MG) in wheat leaf tissue, which is clearly supported by higher lipid peroxidation and membrane damage. It also disturbed the water status and chlorophyll biosynthesis in wheat seedlings. The component of antioxidant defense and glyoxalase system also disrupted owing to acidity stress. Acidity induced damages with growth inhibition increased in a day dependent manner. On the other hand, MA upregulated the majority of the antioxidants, which helps to scavenge toxic ROS and MG in studied seedlings; thus finally improve the water status, photosynthetic pigments as well as the growth of the plant. The performance of MA was prominent after 6 days of stress. Therefore, our results suggested that the seed priming with MA rendered wheat more tolerance to acidity-induced oxidative damage at the early seedling stage.