Aniszewski, Tadeusz .
MB and CR Techniques and TZ and E Tests in Phaseolus lunatus Testa Research.
AS a seed covering, the testa employs different strategies in the highest stratum of plant life and its adaptation to different environments. To study these strategies, the testa was studied using vital and indicator dyes such as methylene blue (MB), Congo red (CR), tetrazolium (TZ) and enzyme (E) tests. These dyes and tests are commonly used in histo- and clinical chemistry. MB is a cationic dye which attracts acidic groups, such as pectines and lignins, and indicates praline synthesis and increased oxidative pentose pathway (OPPP) activity. CR attracts cell wall polysaccharides such as cellulose and some proteins. TZ (2,3,5-triphenyltetrazoliumchloride) is a chemical which, upon reduction, forms deeply coloured pigments, known as monoformazans, and is used for the histochemical detection of dehydrogenases in enzyme diagnosis. The E test detects succinic dehydrogenase (SDH) and acidic phosphase (AcP). These techniques and tests were applied in Phaseolus lunatus testa research and the results clearly prove that these techniques are very useful. MB and CR uptake occurred across the hilum and they flowed to xylem bundles. Both dyes were conducted from the hilum to the endotesta. The TZ and E tests clearly demonstrated the presence of enzymatic activity in the testa. The living parenchymal cells are capable of cell division and exhibit dehydrogenase activity. Dehydrogenases transform colourless tetrazolium into coloured non-diffused formazan. AcP and other hydrolytic enzymes are also important for cytolysis and cell wall degradation. The generally accepted view in the literature is that water is unable to enter the seed unless the testa is broken. Results have explicitly shown that dye is able to penetrate the testa protection system without necessarily breaking the testa. The exo, endo and mesotesta and hilum seem to be regulators in this process.
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1 - University of Joensuu, Department of Biology, Research and Teaching Laboratory of Applied Botany, Joensuu, 80101, Finland
Presentation Type: Oral Paper:Papers for Sections
Date: Tuesday, August 1st, 2006
Time: 2:15 PM