Differences in glucosinolate patterns and arbuscular mycorrhizal status ofglucosinolate-containing plant species

Under defined laboratory conditions it was shown that two glucosinolate-con taining plant species, Tropaeolum majus and Carica papaya, were colonized b y arbuscular mycorrhizal (AM) fungi, whereas it was not possible to detect AM fungal structures in other glucosinolate-containing plants (including se veral Brassicaceae). Benzylglucosinolate was present in all of the T. majus cultivars and in C. papaya it was the major glucosinolate. 2-Phenylethylgl ucosinolate was found in most of the non-host plants tested. Its absence in the AM host plants indicates a possible role for the isothiocyanate produc ed from its myrosinase-catalysed hydrolysis as a general AM inhibitory fact or in non-host plants. The results suggest that some of the indole glucosin olates might also be involved in preventing AM formation in some of the spe cies. In all plants tested, both AM hosts and non-hosts, the glucosinolate pattern was altered after inoculation with one of three different AM fungi (Glomus mosseae, Glomus intraradices and Gigaspora rosea), indicating signa ls between AM fungi and plants even before root colonization. The glucosino late induction was not specifically dependent on the AM fungus. A time-cour se study in T. majus showed that glucosinolate induction was present during all stages of mycorrhizal colonization.