A RAPID VIABILITY ASSAY FOR PLANT SHOOT APICAL MERISTEMS

When plant regrowth in vitro is used as a test for assessing the viabi lity of cultured meristems, the final results are obtained only after 1.5-2.0 months. This hampers investigations, especially those involvin g many samples, for example, investigations of the effects of multiple stresses. A rapid viability assay suitable for both cultured apical m eristems and shoot apices in plants is a prerequisite for successful w ork. Tetrazolium chloride procedure and staining with various dyes (ph enosafranine, Evans blue, and fluorescein diacetate) were compared to assess the viability of shoot apical meristems of potato and strawberr y in vivo and in vitro. In some cases, tetrazolium chloride did not st ain living apices, because its reduction depended on the conditions of plant culturing and on meristem pretreatments with some chemicals. Ph enosafranine and Evans blue stained only damaged tissues of viable api ces. The most successful procedure was apex staining with 0.005% fluor escein diacetate. When treated apices were irradiated with blue-violet light, viable, but not dead, apices fluoresced. Greenish fluorescence appeared within 10 min after apex incubation in fluorescein diacetate and was noticeable for at least an hour.