Ectopic over-expression of the maize beta-glucosidase Zm-p60.1 perturbs cytokinin homeostasis in transgenic tobacco

Kiran, N.S.; Polanská, Lenka; Fohlerová, Radka; Mazura, Pavel; Válková, M.; Šmeral, M.; Zouhar, Jan; Malbeck, Jiří; Dobrev, Petre; Macháčková, Ivana; Brzobohatý, Břetislav

Klíčová slova: beta-glucosidase; chloroplast; cytokinin metabolism
Abstrakt: Transgenic tobacco plants were constructed over-expressing Zm-p60.1, a maize beta-glucosidase capable of releasing active cytokinins from O-glucosides, to analyze its potential to perturb zeatin metabolism in planta. Zm-p60.1 in chloroplasts isolated from transgenic leaves has an apparent Km more than ten-fold lower than purified enzyme in vitro. Transgenic plants grown in the absence of exogenous zeatin were morphologically indistinguishable from wild-type although significant differences in phytohormone levels were observed. When grown on medium containing zeatin, the transgenic seedlings rapidly accumulated fresh weight between 14 and 21 days after sowing leading later to ectopic growths at the base of the hypocotyls. Cytokinin quantification showed that transgenic seedlings grown on medium containing zeatin accumulate active metabolites like zeatin riboside and zeatin riboside phosphate and this might lead to the observed changes.
Autoři z ÚEB: Petre I. Dobrev, Jiří Malbeck