Endogenous auxin and cytokinin contents associated with shoot formation in leaves of pineapple cultured in vitro

the in vitro culture of pineapple leaves on a shoot induction medium (sim) results in the formation of protuberances and further development in shoots, and plantlets. the contents of endogenous indoleacetic acid (iaa) and five cytokinins (cks), n6(2-isopentenyl)adenine (ip), n6(2-isopentenyl)adenosine (ipr), zeatin (z), zeatin riboside (zr) and n6-benzyladenine (ba), present in the basal portion of those leaves, were correlated to the organogenic response that occurs over 15 days of culture. the endogenous auxin/cytokinins ratio was lowest on the 3rd day, mainly due to a strong increase in the ip level. it seems that endogenous ip concentration triggered the induction signal for an organogenic response in pineapple leaf bases. the rise in ip content required the presence of ba and a-naphthaleneacetic acid (naa) in the medium, suggesting that endogenous ip production is regulated in response to these growth regulator uptakes.