Abstract
The number of root nodule is regulated by some control mechanisms. The effects of the phytohormone ethylene and abscisic acid (ABA) on root nodule formation were analyzed in white clover. Nodule number decreased by treatment of ACC, which is a precursor for ethylene. On the contrary, nodule number increased by the treatment of STS, which is a specific inhibitor for ethylene. Exogenous ABA also inhibited root nodule formation after inoculation with rhizobia. And the number of nodules of white clover treated by abamine, which is inhibitor for synthesis of ABA increased dramatically.
Moreover, increase of nodule number by treatment of STS suppressed by the additional treatment of ABA and that by treatment of abamine suppressed by ACC treatment. We hypothesize that control mechanism of the number of root nodules by ethylene and that by ABA is independent.
