Maize plant development and antioxidant defense influenced by selenium-enriched Cyanobacteria species

Abstract

Supplementing plants with selenium promotes their growth, production, and antioxidant activity. Se-enriched cyanobacteria can be utilized for biofertilization of food crops to boost their nutritional and health value. This study aimed to examine the impact of Se-enriched cyanobacteria on Maize's growth and antioxidant response (Zea mays L.). The present investigation examined how distinct Trichormus variabilis, Nostoc oryzae, Anabaena sp., and Oscillatoria sancta responded to selenium at different doses. The results showed that all cyanobacterial isolates failed to grow when exposed to Se > 0.125 mM. Anabaena sp. and Trichormus variabilis were the only isolates to exhibit enhanced antioxidant properties when supplemented with 0.125 mM Se. The two isolates had the highest DPPH scavenging and total antioxidant activity at 0.125 mM Se, with IC₅₀ values of 235.613 and 319.567 µg mL^⁻¹, respectively, and 353.161 and 317.467 mg AAE g^⁻¹, respectively. Furthermore, they showed the maximum activities of superoxide dismutase (11.14, 11.33 U/g, respectively), catalase (25.36, 33.29 U/g, respectively), and glutathione peroxidase (48.69, 51.55 U/g, respectively). Likewise, these two isolates revealed the best phenolic (35.51, 35.84 mg GAE g^⁻¹, respectively) and phycobiliproteins contents (590.47, 1229.32 µg mL^⁻¹, respectively), which led to their application on maize plants as biofertilizers to boost growth, and antioxidant response during the vegetative stage. The results show that maize shoots treated with Anabaena sp.-rich in selenium (T₅) exhibited the highest peroxidase (3.83 U/g), polyphenol oxidase (8.213 U/g), and catalase (132.703 U/g) activities. The highest DPPH scavenging activity (IC₅₀ 251.33 µg mL⁻¹) and total phenolic content (2.507 mg GAE g⁻¹) were observed in maize shoots following treatment with T₅. This study highlights the advantages of cyanobacteria, particularly Anabaena sp. supplemented with selenium, as a biofertilizer that could be a long-term, eco-friendly solution to biofortifying food crops with selenium.