Section 5
Chapter 4,893

Cell length light and carbon 14 labeled iaa transport in pisum sativum cultivar meteor and phaseolus vulgaris cultivar mexican black

Eliezer, J.; Morris, D.A.

Planta (Heidelberg) 149(4): 327-331


ISSN/ISBN: 0032-0935
Accession: 004892468

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The putative auxin-transporting cells of the intact herbaceous dicotyledon are the young, differentiating vascular elements. The length of these cells was considerably greater in dwarf ('Meteor') than in tall ('Alderman') varieties of P. sativum L., and in etiolated than in light-grown plants of P. sativum cv. Meteor and P. vulgaris L. cv. Mexican Black. Under given light conditions during transport these large differences in cell length did not influence the shapes of the transport profiles or the velocity of transport of 14C-labeled IAA applied to the apical bud. However, in both etiolated and light-grown bean and dwarf pea plants the velocity of transport in darkness was .apprx. 25% lower than that in light. Under the same conditions of transport velocities in bean were about twice those observed in the dwarf pea. Exposure to light during transport increased the rate of export of 14C from the labeled shoot apex in green dwarf pea plants but not in etiolated plants. The light conditions to which the plants were exposed during growth and transport had little effect on the rates of uptake of IAA from the applied solutions. The velocity of auxin transport is independent of the frequency of cell-to-cell interfaces along the transport pathway, and in intact plants auxin transport is probably entirely symplastic.

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