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POLAR TRANSPORT OF GROWTH‐REGULATORS IN PITH AND VASCULAR TISSUES OF COLEUS STEMS
Author(s) -
Jacobs W. P.,
McCready C. C.
Publication year - 1967
Publication title -
american journal of botany
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.218
H-Index - 151
eISSN - 1537-2197
pISSN - 0002-9122
DOI - 10.1002/j.1537-2197.1967.tb10730.x
Subject(s) - pith , coleus , auxin , elongation , biology , polar auxin transport , anatomy , parenchyma , botany , epidermis (zoology) , biophysics , vascular tissue , materials science , biochemistry , composite material , ultimate tensile strength , arabidopsis , mutant , gene
Movement of IAA‐C 14 and 2,4‐D‐C 14 through cylinders of known size and histology was compared using liquid scintillation counting. Both auxins showed strongly polar movement, even through pith parenchyma cut from Coleus internode #5, the youngest internode to have ceased elongation. The polar movement was correlated with sizable elongation of the excised cylinders. Velocities of basipetal movement for a given auxin, as determined by the intercept method, showed small or negligible differences between pith and “corner” cylinders. (Corner cylinders comprised mostly vascular tissue, plus some cortical, pith, and epidermal cells.) For IAA, basipetal velocities ranged from 2.1 to 3.3 mm per hr; for 2,4‐D, they were 0.6–0.8. For both auxins there was much more net loss into corner than into pith cylinders, a difference associated with the fact that corner cylinders showed 10 times as many cells in transection. More 2,4‐D moved basipetally through corner than through pith cylinders and the reverse was true of IAA. By chromatographic evidence, all the radioactivity in the basal receiving blocks was still associated with the auxin molecules.