Sugar Accumulation Cycle in Sugar Cane. III. Physical & Metabolic Aspects of Cycle in Immature Storage Tissues

Abstract

PLANT PHYSIOLOGY rate of elongation of immnnature internodes were linearly related, both increasing with increasing temperature provided the plant had adequate water. Changes in the total sugar content of mature tissue were related to the neutral invertase activity of the tissue. The neutral invertase activity and sugar content of mature internodes increased as the temperature was decreased. The results are dliscussed in relation to the concept that invertases of sugar cane storage tissue contribute to the partitioning of available carbohydrate from photosynthesis between the processes of sugar storage and growth.

Sugar Accumulation in Sugarcane

“…Table I and indicate that free-space concentrations of sucrose can approach the same concentration as total sucrose in the tissue. These findings are in complete accord with a role for cell walls in sucrose transport as suggested previously (6,10). Evidence that the cell wall constitutes the major pathway for movement of sugars between sugarcane parenchyma cells and the conducting tissue is reviewed elsewhere (5).…”

“…Plastic capillary tubing was sealed into the ends of the holes and connected into a multichannel peristaltic pump which was used to flow solutions through the holes in a closed system at a flow rate of 2 ml min-'. Sugars in these solutions were assayed (8, 9) on 10-1d aliquots removed either during the course of, or at the end of, a run, and sugar in the tissue was assayed as previously described (10). RESULTS …”

Invertases of Lilium Pollen

“…The presence or absence of metabolizable carbohydrate in the growth media had no effect on development of invertase activity during pollen germination. The synthesis of inner space invertase of sugar cane is repressed by glucose and fructose (26), but this does not appear to occur in germinating lily pollen. Addition of cycloheximide (10 mg/l) caused complete cessation of pollen tube emergence but had no effect on the amount of invertase associated with the pollen wall, which implies that there is no detectable relationship between activity of this enzyme and wall synthesis of the pollen tube.…”

Carbon Partitioning during Sucrose Accumulation in Sugarcane Internodal Tissue

“…However, despite the apparent carbon cycling, only 10% of the total radioactivity of compounds soluble in 70% ethanol was lost during a 10-h incubation period of sugarcane culm tissue (Sacher et al, 1963). This suggests a relatively small allocation of carbon to respiration and cell wall synthesis.…”

“…Knowledge about carbon partitioning between different cellular constituents in sugarcane culm tissues is limited to partitioning within the sugar pool (Sacher et al, 1963;Batta and Singh, 1986;Lingle, 1989). In sugarcane cellsuspension cultures, increased carbon partitioning into SUC is at the expense of both respiration and structural material under nitrogen-limiting conditions (Veith and Komor, 1993).…”