The Agrobacterium tumefaciens C58-6b gene confers resistance to N6-benzyladenine without modifying cytokinin metabolism in tobacco seedlings

Ivan Gális, Petr Šimek, Jiří Macas, Helena Zahradníčková, Josef Vlasák, Hiroetsu Wabiko, Walter Van Dongen, Henri A. Van Onckelen, Miloš Ondřej

Research output: Contribution to journalArticlepeer-review

13 Citations (Scopus)


The 6b gene of Agrobacterium tumefaciens has been demonstrated to modify the activity of the plant growth regulators, auxin and cytokinin. To study the possible mode of action of the gene, tobacco (Nicotiana tabacura L. cv. Samsun) plants were transformed with the A. tumefaciens C58-6b gene. Seeds obtained from morphologically normal transgenic as well as wild-type plants were germinated on media supplemented with growth-inhibitory levels of cytokinin, N6-benzyladenine (BA). The transgenic seedlings showed increased resistance to cytokinins, as reflected by continuous shoot development, whereas further growth of the wild-type plants beyond the cotyledonary stage was inhibited. Concurrently, the levels of 6b gene transcripts in transgenic seedlings increased greatly upon BA treatment. Since glucosylation of BA represents the main inactivation mechanism of the hormone, we analyzed BA glucoside formation during the early stages of seedling growth. Intracellular-levels of the major BA metabolite, N6-benzyladenine-7-glucoside (80-92%), as well as other BA-derived components were found to be comparable in transgenic and wild-type seedlings. Therefore, increased resistance of the C58-6b transgenic seedlings to cytokinins could not be directly attributed to enhanced BA glucosylation and subsequent hormone inactivation.

Original languageEnglish
Pages (from-to)453-461
Number of pages9
Issue number4
Publication statusPublished - Oct 1999
Externally publishedYes


  • 6b gene
  • Agrobacterium (6b gene)
  • Cytokinin resistance
  • Nicotiana (transformed)
  • Transgenic plant (tobacco)

ASJC Scopus subject areas

  • Genetics
  • Plant Science


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