Title: SEASONAL INTERNODE DEVELOPMENT AND SUGAR METABOLISM IN SUGARCANE
Submitted to: Crop Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: December 15, 1996
Publication Date: N/A
Interpretive Summary: Sugarcane cultivars reach harvestable juice quality at different times of the growing season. Plant breeders would like to be able to identify those plants that reach that quality early. Identifying differences in sugar metabolism between cultivars and during the growing season would help identify the genes that contribute to high quality in sugarcane. This study looked at sugars and some enzymes that metabolize sugar in the developing stem of sugarcane where sugar is stored. Two cultivars were used, but few differences between them were observed. Tissue that started developing late in the growing season matured faster; that is, it stopped growing and started storing sugar earlier than the tissue that started developing early in the growing season. However, the study was unable to identify changes in enzymes that would account for the changes in maturity.
The profile of sugar along the stalk of sugarcane (Saccharum sp. hybrids) varies during the growing season and between cultivars. Changes in sucrose accumulation and metabolism in storage tissue with development, changes in sucrose metabolism with time, and differences in sugar metabolism between an early cultivar, 'CP70-324,' and a late cultivar, 'TCP81-3058,' were determined. Elongating internodes of both cultivars were tagged at intervals from July to October during 1993 and 1994 in field plots near Mercedes, TX. These were periodically sampled during their development, and sugars and enzymes of sucrose metabolism, sucrose synthase (SS), acid invertase, and neutral invertase were assayed. Internodes which developed later in the growing season were shorter and accumulated less dry weight than those that developed earlier. Total sugar and sucrose concentrations in the late internodes approached those of early internodes. Water content tof all internodes decreased from about 90% to about 72% during development late internodes reached this low water content in less time than early internodes. Activities of SS and both invertases were highest in the youngest internodes, and decreased to a steady state in fully elongated internodes. The steady-state SS activity was greater than the other enzymes assayed. No significant differences were observed between the cultivars.