Effect of medium composition on production of Striga hermonthica (Del.) Benth germination stimulant(s) by Menispermum dauricum (DC.) root cultures

Germination of Striga hermonthica (Del.) Benth, a noxious parasitic weed on cereals, requires an exogenous stimulant produced by the roots of host and some nonhost plant species. Root cultures of Menispermum dauricum (DC.), a nonhost broad-leaved herbaceous plant, produced a group of substances that induce the parasite germination. This paper reports the establishment of a high-stimulant-producing M. dauricum root culture by manipulation of culture composition. A modified B5 medium (MB5) containing 35.7 mM nitrogen at a NO3-/NH4+ ratio of 1:42, 0.1 mM Fe2+, 1.0 mM Ca2+, 0.55 mM inorganic phosphorus, 0.28 mM inositol, 4.1 mu M nicotinic acid, 3.7 mu M I pyridoxine hydrochloride, 14.8 mu M thiamin hydrochloride, 1 mu M 1-naphthaleneacetic acid (NAA), and 4% sucrose sustained root growth for a longer period and increased root biomass by >30% and stimulant production by 5-fold, in comparison to the standard B5 medium supplemented with 3% sucrose and 1 mu M NAA.