The effect of jasmonic acid (JA), in a wide range of concentrations (0.01-100 ~M), on the development of potato plantlets (Solanum tuberosum L.cv. Vesna) was investigated in order to discriminate between physiological and supraoptimal effects of this growth regulator in vitro. Concentrations from 0.I-I I~M significantly increased the length of developed plants. Application of JA in these concentrations resulted in a very well differentiated root system with many lateral branches. With increasing JA concentrations, the main roots shortened and thickened. Concentrations higher than 10 v~M led to the compaction of the stem, roots, and root hairs, giving a stunted appearance to the plants. The effect of JA on cell wall regeneration and callus formation was observed in potato leaf protoplast culture. JA at concentrations from 0.01-1 ixM stimulated cell division and microcaUi development.

No abstract

SUMMARYIn experiments on spruce we have shown that jasmonic acid (JA), a cyclopentanone fatty acid, influences the ectomycorrhizal formation: we therefore also applied it to an endomycorrhizal symbiosis.Garlic {Allium sativum (L.)) bulbs were potted into substrates inoculated or not with arbuscular mycorrhizal fungi (AMF), and one half of the plants was foliar-treated with 5 /tM JA. A synergistic effect of JA treatment and AMF inoculation on shoot length was found. Root growth of inoculated plants was accelerated especially when JA was applied. Either JA or AMF inoculation significantly enhanced bulb development. Mycorrhizal colonization was promoted and the development of arbuscules and vesicles was enhanced upon JA application.

No abstract

sulphur and phosphorus. As a result of reduced uptake, nega-Hydroponically grown Picea abies (L.) Karst. seedlings were exposed to lead (5 mM Pb) and zeatin-riboside (ZR) treat-tive effects of Pb on root elongation were largely ameliorated by ZR. In addition, ZR alleviated the Pb-induced decrease in ments (1 mM, periodically) in a factorial experiment. Exposure of the roots to cytokinin reduced the total Pb content in photosynthetic pigments, although it stimulated Pb translocathe spruce seedlings by ca. 50%. X-ray microanalysis revealed tion to the shoot. The results demonstrate that Pb translocation to the shoot is not a simple uncontrolled process in which that this was mainly due to decreased Pb concentrations in a fixed proportion of Pb taken up by the roots is delivered to stelar tissues of the root, a major part of which was located in the shoots. granules of parenchymatic cells containing high amounts of Von Schwartzenberg et al.