Uptake, distribution, and metabolism of 1-naphthaleneacetic acid and indole-3-acetic acid during callus initiation from Actinidia deliciosa tissues

1-Naphthaleneacetic acid (NAA) and 6-benzyladenine (BA) were required for i n vitro callus formation at the basal edge of kiwifruit (Actinidia delicios a [A. Chev] Liang and Ferguson, cv. Hayward) petioles. The uptake, metaboli sm, and concentration of NAA and indole-3-acetic acid (IAA) content were ex amined in the explants during the callus initiation period. After 1, 6, 12, 24, 48, and 96 h of culture in the presence of [H-3]NAA, petioles were div ided into apical, middle, and basal portions and analyzed. Except for a hig h IAA level measured at 12 h, IAA content decreased in tissues during a cul ture period of 96 h. NAA uptake was higher in petiolar edges than in the mi ddle portion, and NAA was rapidly conjugated with sugars and aspartic acid inside the tissues. The amide conjugation was triggered in apical and basal portions from 12 h and in the middle part from 48 h, with alpha-naphthylac etylaspartic acid being the major metabolite. Free-NAA concentration in cul tured petioles achieved an equilibrium with the exogenously applied NAA (0. 27 mu M) from 12 h, and it remained constant thereafter. The relationships between the role attributed to NAA and BA in the initiation and the mainten ance of disorganized growth of callus in kiwifruit cultures are discussed.