A cultivation method was developed to enable exposure of ectomycorrhizal plants with intact extramatrical mycelium to solutions containing different concentrations of aluminium or heavy metals. Pinus sylvestris seedlings colonized by Suillus variegatus (two isolates), Rhizopogon roseolus or Paxillus involutus (two isolates) were used. Seedlings were transferred to Petri dishes containing glass beads and exposed to elevated concentrations of Al, Cd, Cu, or Ni in two ways: immediately following transfer; and after allowing mycorrhizal seedlings to develop an extraradical mycelium that colonized the interface between the upper surface of the beads and the metal- containing solution. Production of organic acids in mycorrhizal and non-mycorrhizal systems was measured by withdrawing samples from the solution and analyzing by HPLC. In most experiments, levels of oxalic acid were significantly higher in mycorrhizal treatments than in non-mycorrhizal controls. The measured levels of organic acids were variable, but the results obtained suggest that production of oxalic acid is stimulated by exposure to elevated Al in mycorrhizal seedlings colonized by S. variegatus and R. roseolus. Elevated Al concentrations also increased oxalic acid production by non-mycorrhizal seedlings significantly in two of four Al experiments performed, but the measured concentrations were significantly lower than in corresponding mycorrhizal treatments in both cases. Malonic acid was found in the culture solution of non-mycorrhizal and P. involutus- colonized seedlings, but only trace amounts were found in S. variegatus or R. roseolus-infected seedlings. Citric, shikimic, lactic, acetic, propionic, fumaric, formic, iso-butyric and butyric acid were found in variable concentrations. Production of oxalic acid by seedlings colonized by S. variegatus BL or P. involutus was not stimulated by exposure to 0.44 μM Cd or 17 μM Ni. Exposure to 0.157 mM Cu in two separate experiments using P. involutus 87.017 and two strains of S. variegatus (BL and I59) appeared to stimulate production of oxalic acid irrespective of mycorrhizal status or species.

New Phytologist144 (1999), 283–294

In the November 1999 issue of New Phytologist, we published the research paper entitled ‘Nitrogen-fixing legumes and silvigenesis in a rain forest in French Guiana: a taxonomic and ecological approach’ by J. C. Roggy and M. F. Prévost. Since its publication, it has come to our attention that an important error was introduced into Table 4 during production. The four species Cassia spruceana, Dialium guianense, Dicorynia guianensis and Senna quinquangulata appear erroneously under the heading Mimosaceae, replacing the correct entries of Inga marginata, I. nouragensis, I. paraensis, and I. pezizifera.

We apologize to the authors and to our readers for this mistake.

Under defined laboratory conditions it was shown that two glucosinolate-containing plant species, Tropaeolum majus and Carica papaya, were colonized by arbuscular mycorrhizal (AM) fungi, whereas it was not possible to detect AM fungal structures in other glucosinolate-containing plants (including several Brassicaceae). Benzylglucosinolate was present in all of the T. majus cultivars and in C. papaya it was the major glucosinolate. 2-Phenylethylglucosinolate was found in most of the non-host plants tested. Its absence in the AM host plants indicates a possible role for the isothiocyanate produced from its myrosinase-catalysed hydrolysis as a general AM inhibitory factor in non-host plants. The results suggest that some of the indole glucosinolates might also be involved in preventing AM formation in some of the species. 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 signals between AM fungi and plants even before root colonization. The glucosinolate induction was not specifically dependent on the AM fungus. A time-course study in T. majus showed that glucosinolate induction was present during all stages of mycorrhizal colonization.

New Phytologist145 (2000), 1–3

In the January 2000 issue of New Phytologist, we published the forum article entitled ‘Cadmium for all meals – plants with an unusual appetite’ by U. Krämer. Since its publication, it has been brought to our attention that an error was introduced during typesetting. In the text several instances of concentrations are erroneously presented as mg−1: these should be kg mg−1.

New Phytologist145 (2000), 367–421

In the March 2000 issue of New Phytologist, we published the Tansley review entitled ‘Numerical and physical properties of orchid seeds and their biological implications’ by J. Arditti and A. K. A. Ghani. Since its publication, it has been brought to our attention that an error was introduced during typesetting. On p. 391, Eqn 5, the horizontal line above the right side of the equation should form a square root sign.

We apologize to the authors and to our readers for these mistakes.