Analysis efficiency of Iranian Ajowan ecotypes on hairy root production mediated by different Agrobacterium rhizogenesis strains

Ajowan (Trachyspermum Ammi L.) is one of the most important medicinal plants native to the Middle East and Iran. The antibiotic properties of its essential oils are related to the relatively high content of thymol. In this study, the possibility of hairy root production was investigated in a pre-experimental study considering many factors affecting transgenic efficiency, including explant type, immersion time, and the type of culture medium. Optimal conditions for the pre-experiment were set up based on the completely randomized design with seven Agrobacterium rhizogenes strains (A3, A6, A7, 4404, AATCC15834, R1000, A4) and six selected Ajowan ecotypes (Ardebil, Shiraz, Arak, Sarbishe, Qom, and Rafsanjan). The root-related morphological characteristics were measured to study the effect of main factors on the hairy root production and the bacterial strains in terms of hairy root induction. Based on the results, the highest percentage of hairy roots in Ardebil ecotype was induced by ATCC15834 strain (50%) and the lowest percentage was related to Rafsanjan ecotype induced by A6 (10%). The highest positive and significant correlation was observed in dry and wet weights (r=0.95), root frequency percentage and root length (r=0.80). The highest amount of phenolic compounds in hairy roots (240 mg/g dry weight matter) was associated with the Ardebil ecotype induced by strain ATCC15834. In this study, Shiraz and Ardebil ecotypes were identified as the best ecotypes, A4 and ATCC15834 strains as the most suitable strains, and suggested for future studies.