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The transport and metabolism of gibberellins A 1 and A 5 in excised segments from internodes of Phaseolus coccineus
Author(s) -
Jacobs William P.,
Beall Frederick D.,
Pharis Richard P.
Publication year - 1988
Publication title -
physiologia plantarum
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.351
H-Index - 146
eISSN - 1399-3054
pISSN - 0031-9317
DOI - 10.1111/j.1399-3054.1988.tb09161.x
Subject(s) - plant stem , phaseolus , gibberellin , agar , shoot , botany , biology , metabolism , chromatography , incubation , chemistry , biochemistry , bacteria , genetics
Jacobs, W. P., Beall, F. D. and Pharis, R. P. 1988. The transport and metabolism of gibberellins A 1 and A 5 in excised segments from internodes of Phaseolus coccineus . ‐Physiol. Plant. 72: 529–534. The transport and metabolism of gibberellins (GAs) ([ 3 H]‐GA, and [ 3 H]‐GA 5 ) of high specific radioactivity were investigated in excised segments from young internodes of Phaseolus coccineus L. Both GA 1 and GA 5 are native to this species and present in shoot tissue. The segments, 5.1 mm long, were incubated for 6 h in the horizontal position with agar donor blocks containing the [ 3 H]‐GA on the morphological apical or basal ends and with plain agar receiver blocks on the opposite end. At the end of incubation, the individual agar blocks were analyzed immediately for total radioactivity, or both blocks and intervening tissue were frozen and freeze‐dried for later chromatographic analysis. The movement of both [ 3 H]‐GA, and [ 3 H]‐GA 5 was found to be consistently without polarity. However, approximately 5‐fold more [ 3 H]‐GA, than [ 3 H]‐GA 5 was transported through the Phaseolus segments into receivers when equal amounts were in the donors. The extractable radioactivity from receiver blocks was primarily that of the donor GA. No putative GA conjugates were found in any class of receivers, but more GA metabolites were found in the free acid fraction from acropetal than basipetal receivers. Chromatographic analysis by reversed phase C 18 high performance liquid chromatography of the tissue segments showed that [ 3 H]‐GA, was metabolized more than [ 3 H]‐GA 5 . Tissue adjacent to receiver blocks contained not only the precursor GA from the donor, but also polar ‘free GA metabolites’ and putative GA glucosyl conjugates. These results provide evidence that GA., which is the known ‘effector’ GA for elongation in shoot tissue of several species, is more effectively transported than GA 5 (a known precursor of GA 1 ) or than GA 1 s more polar metabolites.