The effect of strigolactone on the morphophysiological and biochemical characteristics of Thymus daenensis Celak.

In the present study, the effect of foliar spraying of strigolactone (۰, ۵, and ۱۰ μM) on the physiological and biochemical responses of Thymus daenensis Celak plant under drought stress (۹۰, ۶۰ and ۳۰% of field capacity (FC)) was examined in a factorial experiment based on a completely randomized design with three replications in the Agriculture and Resources Campus Natural Sciences of Tehran University, Karaj. This study provided compelling evidence of increased drought stress tolerance in the Thymus daenensis Celak plant when treated with exogenous strigolactone at the flowering stage. Plants exposed to drought stress exhibited a significant decline in growth and development, as evidenced by shoot growth characteristics, photosynthetic pigments, and antioxidant enzyme activities. Drought stress led to a strong increase in hydrogen peroxide (۲۱۲%) and malondialdehyde (۱۵۱%), and these changes were strongly linked to growth retardation. The highest value of total phenol (۵۶.۴۹ mg GA.g-۱ DW), flavonoid (۹۶.۲۴ mg Q.g-۱ DW), proline (۴.۱۴۷ μmol g-۱), superoxide dismutase (۲۴.۲۶-unit mg-۱ protein), catalase (۴۴.۵-unit mg-۱ protein), and peroxidase (۲۶.۹ unit mg-۱ protein) enzymes activity as well as the highest amount of essential oil (۰.۴۸% by volume/weight) and the highest amount of thymol (۱.۹۳%) in Foliar spraying of ۱۰ micromolar strigolactones under irrigation conditions of ۳۰% of the agricultural capacity of Thymus daenensis Celak were obtained with Foliar spraying of ۱۰ micromolar strigolactones under deficit irrigation ۳۰% EFTc. In conclusion, strigolactone reduced the negative effects of deficit irrigation on Thymus daenensis Celak by improving water relations, increasing photosynthetic pigments, increasing secondary metabolites, osmotic adjustment, and enhancing antioxidant enzymes activities that regulated the homeostasis of reactive oxygen species. To our knowledge, this is the first study on the role of strigolactone in the mechanism of tolerance to drought stress in Thymus daenensis Celak. Also, based on the results of this research, strigolactone can be used as an efficient biological elicitor to improve quantitative and qualitative yield in thyme. It is recommended that these compounds be used as the best option for achieving sustainable agricultural goals and reducing environmental risks.