Mitigation of nickel and lead stress in wheat (Triticum aestivum L.) by Arthrospira platensis and zinc–boron: effects on metal bioaccumulation, plant growth, antioxidants, and gene expression

Crop productivity and food safety are seriously threatened by heavy metal contamination, especially with nickel (Ni) and lead (Pb). The purpose of this study was to assess how well zinc–boron (Zn–B) foliar application and irrigation with Arthrospira platensis extract (APE) reduced Ni and Pb stress in wheat (Triticum aestivum L.). After being treated with 10% APE or Zn–B, wheat plants were exposed to 100 μM Ni or Pb. Gene expression, heavy metal accumulation, antioxidant enzyme activities, photosynthetic efficiency, and plant growth parameters were evaluated. Growth, photosynthetic pigments, and antioxidant defenses were all markedly hampered by both metals, but Ni’s effects were more pronounced. These effects were successfully lessened by APE treatment, which restored shoot and root length, leaf area, and photosynthetic efficiency (Fv/Fm) better than Zn–B. Additionally, APE increased antioxidant activity (SOD, CAT, APX), and their corresponding genes were upregulated. Furthermore, APE enhanced yield characteristics, such as spike length and grain weight, and dramatically decreased Ni and Pb accumulation by 57.4% and 50.9%, respectively. Potential in phycoremediation is suggested by increased bioconcentration and transfer factors for Zn and B under APE treatment. According to these results, APE is a viable, environmentally friendly method for improving plant resistance to heavy metal stress, increasing wheat yield, and lowering possible health hazards.