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Reversal of the Direction of Photosynthate Allocation in Urtica dioica L. Plants by Increasing Cytokinin Import into the Shoot
Author(s) -
Fetene M.,
Beck E.
Publication year - 1993
Publication title -
botanica acta
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.871
H-Index - 87
eISSN - 1438-8677
pISSN - 0932-8629
DOI - 10.1111/j.1438-8677.1993.tb00746.x
Subject(s) - shoot , urtica dioica , botany , cytokinin , apex (geometry) , biology , horticulture , auxin , biochemistry , gene
The natural cytokinin import from the root into the shoot of Urtica dioica plants was enhanced by supplying zeatin riboside (ZR) solutions of various concentrations to a portion less than 10 % of the root system after removal of their tips. After 6 h ZR pretreatment of the plants, 14 CO 2 was supplied for 3 h to a mature (source) leaf or to an expanding leaf and the 14 C‐distribution in the whole plant was determined after a subsequent dark period of 14 h. ZR substantially increased 14 C fixation by the expanding leaves and also enhanced export of carbon and transport to the shoot apex. The effect of the hormone treatment was, however, more pronounced when the 14 CO 2 was supplied to a mature leaf. In the control plants these leaves exported carbon only to the roots: When the amount of the natural daily ZR input from the roots to the shoot was enhanced by 20%, the bulk of the 14 C exported from a mature leaf moved to the shoot apex and only a minor portion of 14 C was still detected in the root fraction. A several‐fold increase of the natural daily ZR input into the shoot resulted in a flow of 14 C only to the growing parts of the shoot. The results suggest control of the sink strength of the shoot apex by ZR in Urtica diocia .