An Efficient Protocol for Direct Somatic Embryogenesis in Medicinal Tree Murraya Koenigii (L.)

Murraya koenigii (L.) Spreng, popularly known as curry leaf plant, is a small aromatic tree belonging to the family Rutaceae that grows widely in Southeast Asia. Its leaves are slightly pungent, bitter, and acidulous in taste. Fresh and dried leaves are used extensively as a flavoring agent in many Indian culinary practices. The fresh leaves of this tree possess antimicrobial, topoisomerases, and mosquitocidal inhibition and antioxidant properties. A reproducible protocol for direct somatic embryogenesis was established in Murraya koenigii. The hypocotyle, cotyledons and root segments were excised from 60 days old in vitro grown seedlings.  Globular somatic embryos were induced on MS medium supplemented with 2.0 mg/l 6-benzyladenine (BA), 0.5 mg/l α-naphthaleneacetic acid (NAA) and 1.0 mg/l thidiazuron (TDZ). The best result obtained for the average frequency of somatic embryos was from hypocotyle explants, which was significantly higher than cotyledons and root explant. The highest frequency of somatic embryos was recorded from hypocotyle segments in 6 weeks. The age and type of explant and concentration of TDZ played an important role in the development of somatic embryos. The heart and torpid stages of all the somatic embryos were also recorded. Over 95% of the somatic embryos, irrespective of their origin, germinated after 4 weeks in 1/2 MS basal media. Well-rooted plantlets were successfully acclimatized.