AUXIN-CYTOKININ INTERACTIONS IN WILD-TYPE AND TRANSGENIC TOBACCO

Citation
S. Eklof et al., AUXIN-CYTOKININ INTERACTIONS IN WILD-TYPE AND TRANSGENIC TOBACCO, Plant and Cell Physiology, 38(3), 1997, pp. 225-235
Citations number
59
Categorie Soggetti
Plant Sciences
Journal title
ISSN journal
00320781
Volume
38
Issue
3
Year of publication
1997
Pages
225 - 235
Database
ISI
SICI code
0032-0781(1997)38:3<225:AIIWAT>2.0.ZU;2-S
Abstract
Cytokinins and auxins are important regulators of plant growth and dev elopment, but there is incomplete and conflicting evidence that auxins affect cytokinin metabolism and vice versa, We have investigated thes e interactions in Nicotiana tabacum L. by separate in planta manipulat ion of levels of the hormones followed by analysis of the induced chan ges in the metabolism of the other hormone, Cytokinin-overproducing pl ants (expressing the Agrobacterium tumefaciens ipt gene) had lower tha n wild-type levels of free IAA, and reduced rates of IAA synthesis and turnover, but there were no differences in the profiles of metabolite s they produced from fed IAA, Similarly, auxin-overproducing plants (e xpressing the A, tumefaciens iaaM and iaaH genes), had lower levels of the major cytokinins than wild-type plants and lower cytokinin oxidas e activity, but there were no differences in the profiles of metabolit es they produced from fed cytokinins, The data demonstrate that cytoki nin or auxin overproduction decreases the content of the other hormone , apparently by decreasing its rate of synthesis and/or transport, rat her than by increasing rates of turnover or conjugation. Implications for the importance of cytokinin:auxin ratios in plant development are considered.