Evolution of Carbohydrates in Tissue Culture Medium and Leaves of Guzmania 'Hilda'

Tissue culture is a commonly used technique for the propagation of bromeliads. As sucrose being a carbohydrate source and important for root development, it is mostly added to the culture medium. In this research Guzmania ‘Hilda' plantlets were grown in vitro for 8 weeks on a rooting medium with variable initial sucrose concentrations (0, 22.5, 25, 40 g/L). It was showed that already after 4 weeks almost all sucrose is gone from the media (except for the highest sucrose concentration 40 g/L), but in the meanwhile glucose and fructose (not present at the start) was formed. During the next 4 weeks also in the medium with 40 g/L all the sucrose was gone and more and more hexoses were measured. Knowing the plants had nothing of the transport sugar sucrose left in the media after 4 weeks, there should be other mechanisms that explain the growth of the plants for the last 4 weeks under in vitro conditions. It was seen that after 4 and 8 weeks the plants had a sucrose concentration dependent amount of starch in their leaves, so one possibility is that they use this stored carbohydrates to support growth at times when no sucrose was available in the medium. Actually in this research it was shown that the amount of starch in the leaves was lower after 8 than after 4 weeks of growth, suggesting the plants used the starch source.status: publishe