Coordinate and Noncoordinate Changes in Enzyme Activities in Pentose Phosphate Cycle in Poplar : A Control of Enzyme Activities in Differentiated Xylem

概要

論文の詳細を見る
Activities of glucose 6-phosphate and 6-phosphogluconate dehydrogenases, transketolase and transaldolase in twigs of Populus gelrica were measured throughout a year. In the living bark, activities of the four enzymes of the pentose phosphate cycle changed at about the same time in the life cycle of the plant. In the differentiating xylem cells there also occurred a simultaneous change in the four enzyme activities. After differentiation of cambium to xylem, the high levels of the four enzyme activities fell gradually and reached minimum levels by early September. In early September, the former two dehydrogenase activities began to rise again, while the latter two transferase activities continued to decrease. The elevated levels of the two dehydrogenases in the differentiated xylem remained unchanged in the non-growing period of the life cycle of the plant. Such a changing pattern of enzyme activities in the life cycle suggested that the pentose phosphate cycle in the differentiated xylem is interrupted in part at the step of transketolase reaction, which results in an increased supply of pentoses and NADPH. Moreover, these characteristic changes in the enzyme activities in the xylem are correlated with the changes in the fine structures of the cells.
日本植物生理学会の論文