Striga hermonthica (Del.) Benth Germination Stimulant(s) from Menispermum dauricum (DC.) Root Culture

Abstract

Germination of Striga hermonthica, an important root parasitic weed on cereals, is induced by stimulants exuded by roots of host and some nonhost plants. Efforts to isolate active compounds have focused on root exudates from intact plants. In this paper, a much easier and less laborious novel approach, based on root cultures, is described. Menispermum dauricum roots cultured in a modified B5 medium produced and exuded into the medium compounds with activity comparable to that of the synthetic strigol analogue GR24. The active components stimulate germination by induction of ethylene biosynthesis. Their accumulation in roots and culture medium, as indicated by activity, was at a maximum 6−8 weeks after subculturing and was positively correlated with root growth (r = 0.76−0.92). HPLC and TLC of the culture filtrate revealed at least two or three compounds, none of which had chromatographic properties consistent with those of strigol. The results indicate the potentials of root cultures as a possible source of novel Striga germination stimulants. Keywords: Germination stimulant; root culture; Striga hermonthica