The aim of this study was to determine the activity of cytokinin dehydrogenase (CKX) and to measure other biochemical components in the primary leaves and radicles of castor seedlings (BRS Energia) in the initial phase of growth. The crude protein extract obtained after a 1-h extraction from the root tissues of seedlings showed no detectable CKX enzymatic activity when incubated with the substrate isopentenyl adenine for 1 h. However, after precipitation with ammonium sulfate at 70% saturation, the pellet showed CKX activity. The peroxidase enzyme activity was higher in the leaves than in the radicles. The total and reducing sugar content was 1.5 times higher in the leaves than in the radicles. The amino acid and protein contents were 6.4 and 9.2 times higher in the leaves than in the radicles, respectively.

A mobilização das proteínas de sementes de Pisum arvense L. durante a germinação na ausência de luz foi estudada. As sementes foram completamente exauridas de suas reservas após 22 dias de germinação e as plântulas cresceram até o 18° dia de germinação. Experimentos de eletroforese em gel de poliacrilamida em presença de SDS indicaram que as principais bandas protéicas, correspondendo às proteínas de reserva de alta massa molecular, foram detectadas apenas até o 7° dia após a germinação. Entretanto, as bandas protéicas correspondentes às lectinas da semente puderam ser detectadas ao longo de todo o processo germinativo, sugerindo que essas proteínas são fortemente resistentes à ação das proteases da semente e devem, de alguma forma, ser importantes para o estabelecimento das plântulas. A atividade hemaglutinante nos cotilédones foi detectada até o 22° dia de germinação, indicando que as lectinas também permaneceram ativas quando os cotilédones estavam bastante exauridos de suas reservas.

ABSTRACT - The mobilization of seed proteins from Pisum arvense L. during germination in the absence of light was studied. The seeds were found to be completely consumed 22 days after germination and seedlings ceased growth after the 18th day. SDS-PAGE indicated that the main protein bands correspond to high molecular mass storage proteins which undergo proteolysis in the initial stages of germination and are not detected after the 7th day of germination. However, the corresponding lectin profiles were detected during the entire germination process, suggesting that these proteins are strongly resistant to seed proteolytic enzymes and should be important for seedling establishment. Furthermore, haemagglutinating activity in cotyledons was detected until 22 days after germination, indicating that the lectins remain active even in senescent cotyledons.