Thidiazuron Stimulation of Apple Shoot Proliferation in Vitro

Abstract

Thidiazuron stimulated shoot proliferation on shoot tip explants of ‘Gala’ apple ( Malus domestica Borkh.) when incorporated in Linsmaier-Skoog medium at concentrations of 10, 1, and 0.1 μ m . Shoot numbers with thidiazuron were equivalent to, or greater than, the number produced when using 4.4 μ m BA in the medium, but the shoots were shorter than with BA. At 10 and 1 μ m thidiazuron, shoot leaves were narrow, had pointed laminae, and were somewhat distorted. Shoot proliferation continued when explants from the 2 highest thidiazuron concentrations were transferred to cytokinin-free medium. Shoots from cultures grown at all 3 concentrations of thidiazuron rooted after 1 to 2 subcultures on cytokinin-free medium. Chemical names used: N -(phenylmethyl)-l H -purin-6-amine (BA) and N -phenyl- N ′-l,2,3-thiadiazol-5-ylurea (thidiazuron).