Carbohydrate translocation in raspberry & soybean

Abstract

To test the hypothesis that sucrose is the form in which carbohydrate is translocated in phloem, experiments were performed on Canby variety raspberry and Hawkeye variety soybean using the approach of Swanson and El Shishiny with Carbon-14-labeled CO2. Glucose and fructose were found to be radio-chemically equal in phloem tissue and the ratio of radioactive sucrose to hexoses increased with translocation distance. These relationships support the proposal that sucrose is translocated and the glucose and fructose found in the phleom result from hydrolysis of sucrose. Explanations are proposed concerning differences in these findings as compared with earlier work with these species. The oligosaccharide raffinose was also found in the leaves and bark of soybean and raspberry and it is suggested that this compound may also be translocated in the phloem.