Stimulation of naphthoquinone production in Impatiens balsamina root cultures by methyl jasmonate

Lawsone (1), lawsone methyl ether (2) and methylene-3,3′-bilawsone (3) are pharmacological active naphthoquinones (NQs) found in Impatiens balsamina L. (Balsaminaceae) [1,2]. I. balsamina root cultures have been established from the young leaf explants in liquid B5 medium supplied with 0.1mg/l α-naphthalene acetic acid, 1.0mg/l Kinetin, 2.0mg/l and 6-benzyladenine [3]. However, these root cultures produced very low levels of (2). The main aims of this study were therefore to increase NQ production in I. balsamina root cultures using methyl jasmonate (MJ) as an elicitor.

Fig.1: Naphthoquinones found in I. balsamina

Treatment with MJ on day 21 of the root cultures was capable of increasing production of (1) and (2), but not (3). The content of (1) and (2) were increased by MJ treatment in a dose-dependent manner. However, treatment with MJ at 600µM markedly diminished growth of the root cultures, as well as production of (1) and (2). MJ treatment at the concentration of 200µM or higher resulted in the root cultures secreting NQs into the liquid media. An investigation of the optimum concentration of MJ, period of elicitor contact and age of the root cultures for elicitation revealed that the treatment of 21 day old root cultures with 300µM MJ for 36 hr resulted in an increased production of (1), (2) and (3). The production levels were 10.0, 0.78 and 0.23mg/g DW, which were 10.4-, 26.0- and 1.3-fold higher than the levels for the controls.

Acknowledgements: Prince of Songkla University, Thailand Research Fund through the Royal Golden Jubilee Ph.D. Program (Grant No. PHD/0161/2548).

References: 1. Yang, X. et al. (2001) Phytother. Res. 15:676–680.

2. Oku, H. et al. (2002) Biol. Pharm. Bull. 25:658–660.

3. Sakunphueak et al, (2010) Plant Cell Tiss. Organ Cult. In press.