Shirin Yousefian - Department of Plant Bioproducts, National Institude of Genetic Engineering and Biotechnology (NIGEB), Tehran, Iran
Fatemeh Ahmadi Nik - Department of Plant Bioproducts, National Institude of Genetic Engineering and Biotechnology (NIGEB), Tehran, Iran
Tahmineh Lohrasebi - Department of Plant Bioproducts, National Institude of Genetic Engineering and Biotechnology (NIGEB), Tehran, Iran
Sharareh Mirshahvalad - Department of Plant Bioproducts, National Institude of Genetic Engineering and Biotechnology (NIGEB), Tehran, Iran
Shahrokh Gharanjik - Department of Agricultural Biotechnology, Shahrood University of Technology, Shahrood, Iran
Kasra Esfahani - Department of Plant Bioproducts, National Institude of Genetic Engineering and Biotechnology (NIGEB), Tehran, Iran

Mentha aquatica L. as an important medicinal plant is known for its phenolic acids with pharmaceutical properties, especially rosmarinic acid. In order to obtain high amounts of secondary metabolites, the establishment of hairy root cultures through Agrobacterium rhizogenes infection is considered as a suitable alternative. In order to compare the abilities of A.rhizogenes strains to induce hairy roots, the leaf and shoot explants of M.aquatica were used for hairy root induction by five different bacterial strains (ATCC ۱۵۸۳۴, A۱۳, R۳۱۸, A۴, ۹۵۳۴). Furthermore, the effect of phosphate, nitrogen, and reducing environmental acidity on growth and rosmarinic acid content of hairy roots were studied. The results indicated that the percentage of rooting in stem explants (۵۰%) was higher than the leaves (۴۲.۶%). Among the bacterial strains, the strain A۴ showed the highest rooting efficiency. It was also demonstrated that phosphate deficiency and increased phosphate levels significantly increased the rosmarinic acid content of hairy roots. Various effects on hairy root biomass were observed in response to different phosphate levels. However, increasing the amount of nitrogen did not affect the studied factors. It was concluded that different types of explants have different potentials of hairy root formation in interaction with bacterial strains.

Hairy roots, Mentha Aquatic, Phosphate, nitrogen, rosmarinic acid