THE INFLUENCE OF THE PROTEINASE INHIBITOR EP475 ON SOME MORPHOLOGICAL CHARACTERISTICS OF POTATO PLANTS (Solanum tuberosum L. cv. Desiree)

Maruša Pompe¹, Borut Štrukelj², Maja Ravnikar^{1 1}National Institute of Biology, Veèna pot 111, Ljubljana, Slovenia ²Jožef Stefan Institute, Jamova 39, Ljubljana, Slovenia

Abstract EP475 is a synthetic cysteine proteinase inhibitor. The potato plants Solanum tuberosum L. cv. Desir
e grew in node culture in controlled conditions. We added 10mM or 50mM of EP475 to the media to investigate its influence on some morphological and biochemical characteristics. The medium without EP475 was used as a control. The number of nodes of the major shoot increased significantly under the influence of 10mM EP475, but the plants shortened under the influence of 50mM EP475. With the increase of EP475 concentration in the media the primary roots shortened. The number of secondary roots on a single primary root decreased significantly by 50mM EP475. Application of EP475 also resulted in an increased number of lateral shoots and in a significant decrease of leaf areas. The ratio between dry and fresh weights significantly increased in roots, stems and leaves under the influence of EP475. Thus, EP475 decreased the amount of water in plants. Decreased growth and biosynthesis due to EP475 were probably a consequence of decreased activity of endogenous proteinases.