AROMATIC METABOLISM IN PLANTS: II. ENZYMES OF THE SHIKIMATE PATHWAY IN SUSPENSION CULTURES OF PLANT CELLS

Abstract

Liquid suspension cultures were established from tissues of soybean root, wax-bean root, rose stem, reseda stem, horseradish petiole, potato tuber, buckwheat hypocotyl, and of cotyledon, root, and hypocotyl from mung bean. The rose and the reseda cultures required no external supply of growth regulators. Methods of culture and preparation of cell-free extracts are described. Extracts from the cells were assayed for isocitrate dehydrogenase (EC 1.1.1.42), malate dehydrogenase (EC 1.1.1.37), quinate dehydrogenase (EC 1.1.1.24), dehydroquinate dehydratase (EC 4.2.1.10), shikimate dehydrogenase (EC 1.1.1.25), prephenate dehydrogenase (EC 1.1.1.), phenylalanine transaminase (EC 2.6.1.), and phenylalanine ammonia-lyase (EC 4.3.1.5). All of the enzymes were detected in the cultures from mung bean. The isocitrate and shikimate dehydrogenases, dehydroquinate dehydratase, and phenylalanine ammonia-lyase were present in all the cultures. The prephenate dehydrogenase was detected in the mung-bean cultures and the root cultures of soybean and wax bean. Quinate deltydrogenase was detected only in the mung-bean cultures but this represents the first time this enzyme has been found in a plant.