Abscisic acid and gibberellic acid as factors in the translocation of auxin

The effects of abscisic acid (ABA) and gibberellic acid (GA) on the translocation of 2,4,5-trichlorophenoxyacetic acid (2,4,5-T) in beans (Phaseolus vulgaris L. cv. Stringless Greenpd) seedlings were determined. 14C-labeled 2,4,5-T was injected in the stem tissue at the cotyledonary node in 1-μl amounts along with the AB or GA. ABA caused an enhancement of 2,4,5-T translocation to the lower hypocotyl and roots and promoted a decrease in the accumulation of 2,4,5-T in the young expanding shoots and primary leaves. GA promoted the accumulation of 2,4,5-T in young shoots. The enhanced basipetal translocation of 2,4,5-T was measurable after a few hours of treatment and was partially effective even in the presence of the protein synthesis inhibitor cychloheximide. The GA effects on 2,4,5-T translocation were nullified by cycloheximide and were also noted after only a few hours of treatment.