Relationship between endogenous auxin and cytokinin levels and morphogenic responses inActinidia deliciosa tissue cultures.

Thein vitro culture ofActinidia deliciosa petioles results in a decline of cytokinin content and an increase of auxin levels. The addition of plant growth regulators (PGRs) to the medium lead to recovery of the initial auxin content, and callus induction occurs at the basal end of the explants. Endogenous auxin/cytokinin ratio was higher at this side than in the apical one, due to unequal distribution of endogenous PGRs in the cultured petioles. Some of the induced calluses showed shoot formation when they were transferred to proliferation medium. Most important differences found in hormonal content between organogenic and non-organogenic callus concerned benzyladenine levels. In this paper the relationships between explant behaviour and their hormonal content is discussed.