RESUMO
The major purpose of these experiments were to investigate growth of potato storage organs and starch synthesis in minitubers at slow horizontal clinorotation (2 rpm), which partly mimics microgravity, and a secondary goal was to study the activity and localization of phosphorylase (EC 2.4.1.1) in storage parenchyma under these conditions. Miniplants of Solanum tuberosum L. (cv Adreta) were grown in culture for 30 days for both the vertical control and the horizontal clinorotation. During long-term clinorotation, an acceleration of minituber formation, and an increase of amyloplast number and size in storage parenchyma cells, as well as increased starch content, was observed in the minitubers. The differences among cytochemical reaction intensity, activity of phosphorylase, and carbohydrate content in storage parenchyma cells of minitubers grown in a horizontal clinostat were established by electron-cytochemical and biochemical methods. It is shown that high phosphorylase activity is correlated with increased starch content during extended clinorotation. The results demonstrate the increase in carbohydrate metabolism and possible accelerated growth of storage organs under the influence of microgravity, as mimicked by clinorotation; therefore, clinorotation can be used as a basis for future studies on mechanisms of starch synthesis under microgravity.
Assuntos
Metabolismo dos Carboidratos , Fosforilases/metabolismo , Tubérculos/crescimento & desenvolvimento , Rotação , Solanum tuberosum/crescimento & desenvolvimento , Aceleração , Dissacarídeos/metabolismo , Estudos de Avaliação como Assunto , Microscopia Eletrônica , Monossacarídeos/metabolismo , Tubérculos/enzimologia , Tubérculos/metabolismo , Tubérculos/ultraestrutura , Solanum tuberosum/enzimologia , Solanum tuberosum/metabolismo , Solanum tuberosum/ultraestrutura , Amido/metabolismo , Simulação de Ausência de PesoRESUMO
The effect of long-term clinorotation on potato minituber formation and the structural-functional organization of storage parenchyma cell in minitubers has been studied by using methods of organ culture in vitro, light- and electron microscopy, biochemistry as well as phenological observation. It was established some acceleration of growth, changes in the parenchyma cell ultrastructure and in the starch content as well as an intensification of phosphorylase activity in the storage tissue of minitubers under the influence of simulated microgravity.