Relationship between the Balance of Endogenous Growth Substances and Tuberization of Potato (Solanum tuberosum L.) Grown in vitro

Under different photoperiods the changes in contents of some endogenous growth substances, such as so called `tuberization inhibitor' gibberellic acid (GA(3)) and 'tuberization promoter' indole-3-acetic acid (IAA), abscisic acid (ABA) and jasmonic acid (JA), of the plantlets of potato cultivar E-potatol growth in vitro were investigated. The results show that all the growth substances assay varied during tuberization, which illustrate that both 'inhibitor' and 'promoter' involve in tuber formation. A dynamic change of individual substances seem not to be direct factor that influences number of tubers formed although more tubers harvested under a lower GA(3) and higher JA and ABA concentrations in earlier stage of tuber initiation. Interestingly, a very significant relationship between the number of tubers per plantlet and the concentration ratio of GA(3) to JA or ABA was obtained. The relationship fit well to a negative power curve represented by y=ax-b (where, y is number of tubers per plantlet, x is the ratio of GA(3)/JA or GA(3)/ABA), suggesting that the balance between GA(3) and its counteractants may play important role in regulating tuberization. (Abstract)