The increase in diffusible auxin in the dwarf pea following treatment with gibherellin has been shown not to involve the inhibition of IAA oxidase, the rate of basipetal auxin transport, decrease in growth inhibitor, the formation of a complex between gibberellin and auxin, or the enzymatic conversion of tryptophan to ether-soluble auxin. The tryptophan conversion system from plants treated with gibberellin formed four times more water-soluble auxin than did the enzyme preparation from control plants. Thus the increase in water-soluble auxin appears to be the major cause of the higher auxin level in plants treated with gibberellin.
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