Raspor M.*, Motyka V.*, Žižková E., Dobrev P.I., Trávníčková A., Zdravković-Korać S., Simonović A., Ninković S., Dragićević I.C. (*contributed equally)
JOURNAL OF PLANT GROWTH REGULATION
31:
460-470,
2012
Keywords:
Bioactive cytokinins, cytokinin oxidase/dehydrogenase (CKX), in vitro, potato, transgenic, tuberization
Abstract:
Genes encoding cytokinin oxidase/dehydrogenase (CKX) enzymes have been used lately to study
cytokinin homeostasis in a variety of plant species. In this
study AtCKX2-overexpressing potato plants were engineered and grown in vitro as a model system to investigate
the effects of altered cytokinin levels on tuber formation
and tuber size. Protein extracts from shoots and roots of
transformed potato plants exhibited higher CKX activity
compared to control plants. Total endogenous cytokinin
levels were generally not decreased in AtCKX2 overexpressors. However, levels of bioactive cytokinins were
markedly lowered, which was accompanied by increased
levels of O- and N-glucosides in some transgenic lines. The
AtCKX2-overexpressing plants displayed reduced shoot
growth but other symptoms of the ‘‘cytokinin deficiency
syndrome’’ were not recorded. The transgenic plants were
able to produce tubers in noninducing conditions. In
inducing conditions they developed larger tubers than
control. Tubers were also formed on a greater portion of
the analyzed AtCKX2 plants, but with a lower number of
tubers per plant compared to control. Taken together, our
data suggest that cytokinins cannot be regarded simply as
positive or negative regulators of tuberization, at least in
vitro. Interactions with other plant hormones that play an
important role in control of tuberization, such as gibberellins, should be further studied in detail.
Fulltext: contact IEB authors
IEB authors: Petre I. Dobrev,
Václav Motyka,
Alena Trávníčková,
Eva Žižková
Čeština
English