INFLUENCE OF GROWTH-RETARDANTS AND ETHYLENE-GENERATING COMPOUNDS ON CULTURE RESPONSE OF LEAF EXPLANTS FROM WHEAT (TRITICUM-AESTIVUM L)

The influence of the growth retardants LAB 150978, tetcyclacis, and chlormequat chloride (CCC), as well as the ethylene-forming compounds 2-chloroethyl-phosphonic acid (ethephon) and 1-amino-cyclopropane-1-carboxylic acid (ACC, on leaf development and culture response of basal leaf explants has been studied after in vivo treatment of donor seedlings of wheat (Triticum aestivum L. cv. Kolibri). Both classes of compounds gradually reduced shoot growth at 10−6 to 10−4 mol × L−1. However, the growth retardants delayed leaf development, e.g. the tissue zone of callus initiation of the youngest, 3rd leaf was decreased while the low competence of the 2nd leaf base was concomitantly intensified. In contrast, the ethylene-generators promoted development of an additional leaf compared to untreated plants. Since the older leaf retained its culture response and the new leaf exhibited additional callus formation (with enhanced root outgrowth), the responding tissue area and overall callus production per plant were increased by about 50 %. In contrast to the growth retardants LAB 150978 and tetcyclacis, callus proliferation was also substantially stimulated by in vitro treatment of leaf explants with ethephon. Thus, the ethylene-enhanced responsiveness of wheat leaf tissue provided more genetically identical plant material capable of cell division for in vitro culture and genetic manipulation. © 1990, Gustav Fischer Verlag, Stuttgart. All rights reserved.