EFFECTS OF ABSCISIC-ACID AND (-CATECHIN ON GROWTH AND LEACHING PROPERTIES OF CALLUS FROM 4 FRUIT TREE SPECIES())

Shoot explants from four tree fruit species were grown under in vitro culture conditions for studying physiological aspects of growth regula tion as influenced by (+)-catechin and abscisic acid (ABA). Applicatio n of 20 resp. 40 mu M abscisic acid to the standard medium reduced cal lus growth of three fruit species (P. avium, P. cerasus, and P. domest ica). Adding (+)-catechin (68 mu M) in conjunction with ABA to the med ia strongly counteracted the inhibitory effect of ABA alone. By contra st, callus growth of Malus domestica was promot ed about 3-fold by ABA compared to control and that of the combined treatment with (+)-catec hin plus ABA exceeded control by 7-fold. Membrane permeability of the calli was estimated by leakage of both electrolytes and organic compou nds. Application of ABA increased exodiffusion in all four tree specie s as compared to controls, which was reversed by combined treatment wi th (+)-catechin and ABA.