HETEROTROPHIC PLANT-CELL SUSPENSION-CULTURES FOR MONITORING BIOLOGICAL-ACTIVITY IN AGROCHEMICAL RESEARCH - COMPARISON WITH SCREENS USING ALGAE, GERMINATING-SEEDS AND WHOLE PLANTS

Heterotrophically cultured cell suspensions are used increasingly in agrochemical research for screening plant-growth retardants and herbicides which influence plant meristems. For this purpose, a large-scale microscreen has been devised, which permits the objective monitoring of cell division by measuring the conductivity in cell suspensions cultured in test tubes. Comparing the effects of a wide spectrum of growth retardants and herbicides with different primary modes of action, the test was most sensitive to nitrogen-heterocyclic retardants in wheat-cell suspensions and to sulfonylurea > imidazolinone > cyclohexanedione, oxyphenoxypropionic acid, nitrile > glufosinate, phenoxy acid, bipyridylium and diphenyl ether herbicides in maize and oilseed rape cell cultures. As had been expected, inhibitors of photosynthetic processes were only slightly active. The results of the tests were compared with the effects of the compounds on germinating seeds of cress (Lepidium sativum L.) and on photoautotrophic systems using algal cell suspensions (Scenedesmus acutus) and duckweeds (Lemna paucicostata). It is suggested that heterotrophic cell suspensions, in combination with the series of biotests mentioned above, are a valuable complement to the whole-plant screens used routinely in industrial laboratories. They are particularly useful for identifying compounds whose biological activity is masked by limited penetration or translocation behaviour in whole plants.