|Mcgrath, J Mitchell - Mitch|
Submitted to: American Society of Beet Sugar Technologists Proceedings
Publication Type: Proceedings
Publication Acceptance Date: 6/12/2003
Publication Date: 7/19/2003
Citation: Trebbi, D., McGrath, J.M. 2003. Sucrose accumulation during early sugar beet development. In: Proceedings of the American Society of Beet Sugar Technologists. Joint Meeting of the International Institute for Beet Research and the American Society of Beet Sugar Technolgists, February 26 - March 6, 2003, San Antonio, Texas. p. 267-271.
Technical Abstract: This study examined sucrose accumulation in different breeding lines during the first weeks after emergence in order to understand and identify early morphological and physiological differences correlated with final root sucrose content. Six germplasm lines (US H20, SR87, SR95, SR96, SR97, and Syngenta-Hilleshög E17, ranging in harvested sucrose contents from 15 to 18%) were planted with three replications. Samples were harvested weekly from the third to the tenth week post-emergence. Plants were grown in the greenhouse under controlled temperature (15 to 22 C) and photoperiod (16 hours of light per day). At each harvest, roots, leaves, and hypocotyls were weighed and freeze-dried, and hypocotyls diameters were measured. From freeze-dried roots, sucrose was extracted with 80% ethanol and then analyzed with high performance liquid chromatography (HPLC). Transverse sections of roots were also analyzed with the light microscope to detect anatomical differences between lines and during development. Sucrose concentration, expressed as fresh weight, increased from less than 0.5% at the third week (all germplasm) to over 10% by the tenth week, with measured sucrose levels proportional to those from field-harvested beets over the entire eight-week experiment. Incremental changes in sucrose levels were not constant during this period, but followed a step-wise trend of rapid sucrose accumulation alternating with low sucrose accumulation. Sucrose concentration expressed as dry weight reached 55% at the tenth week for all lines and showed the same trend seen as fresh weight. Differential gene expression analysis combined with examination of anatomical differences of root tissues during these alternate developmental stages may provide additional insight on the kinetics and molecular mechanisms of sucrose accumulation in sugar beet.