Interaction between jasmonic and gibberellic acids on in vitro tuberization of potato plantlets

A reverse of the delaying effect of gibberellic acid (GA(3)) was observed i n in vitro tuberization of potato plantlets when the medium contained 0.8 x 10(-5) M jasmonic acid (JA). The promoting effect of JA seemed to be corre lated with the initial absence of growing roots, probably through direct ac tivity of JA in microtuber-producing buds in the stoloniferous shoots. This is based on the fact that JA did not inhibit root growth a posteriori. End ogenous gibberellins (GAs) synthesized by roots did not interfere with the previous activity of YA in tuberization. The absence of a JA promoting-effe ct on tuberization of previously-rooted plantlets could be related to the c apacity of potato roots to synthesize endogenous GAs which might antagonize the JA effect on buds of stoloniferous shoots.