Cyanobacteria Increase the Activity of Enzymes Involved in the Lignin Biosynthesis Pathway in Thymus vulgaris L.

The effects of plant inoculation with plant growth-promoting cyanobacteria on the activity of phenylalanine ammonia-lyase (PAL), peroxidase (POD) and cell wall POD enzymes in T. vulgaris L. were investigated. PAL activity was determined by measuring the production of cinnamic acid when the enzymatic extract reacted with phenylalanine. POD activity was evaluated by measuring the levels of guaiacol generated from the breakdown of hydrogen peroxide using a spectrophotometer. A greenhouse experiment with five replications was carried out using inoculation of five cyanobacteria suspensions (۲.۵%) including Anabaena torulosa ISB۲۱۳, Nostoc calcicola ISB۲۱۵, Nostoc ellipsosporum ISB۲۱۷, Trichormus doliolum ISB۲۱۴ and Oscillatoria sp. ISB۲۱۱۶ on T. vulgaris L. plants during four months. on T. vulgaris L. plants. After four months, the plants were harvested, and the enzyme levels were measured. The statistical analysis revealed that the treatment with Nostoc ellipsosporum ISB۲۱۷ had the most significant impact on PAL enzyme activity in the treated plants. Compared to the control group (۰.۱۳ ± ۰.۰۰۲), the plants treated with T. doliolum ISB۲۱۴ exhibited the highest activity of POD (۰.۶۹ ± ۰.۰۳) enzyme and cell wall POD (۰.۵۳ ± ۰.۰۵). Also, the amount of lignin in the treated plants had a significant increase compared to the control. Considering the valuable medicinal properties of the secondary metabolites found in thyme plants and the crucial role of nutritional management in enhancing the production and quality of this medicinal plant. The usage of appropriate growth stimulants has the potential to enhance the biosynthesis of these compounds. This study demonstrated the successful application of microalgae extract as a completely natural and eco-friendly substance for increasing the yield of T. vulgaris L. plants.