ARS | Publication request: Dehydration accelerates root respiration and impacts sugarbeet raffinose metabolism

Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: November 17, 2008
Publication Date: September 1, 2009
Citation: Lafta, A.M., Fugate, K.K. 2009. Dehydration Accelerates Root Respiration and Impacts Sugarbeet Raffinose Metabolism [abstract]. Journal of Sugar Beet Research. 46(1&2):80.

Technical Abstract: Sugarbeet roots lose water during storage and often become severely dehydrated after prolonged storage and at the outer portions of piles which have greater wind and sun exposure. Sucrose loss is known to be elevated in dehydrated roots, although the metabolic processes responsible for this loss are unknown. To identify processes that contribute to sucrose loss in dehydrated roots, respiration rate and raffinose oligosaccharides (raffinose and stachyose) and their precursors (myo-inositol and galactinol) were determined in sugarbeet roots during four weeks of 10oC storage at high (85%) and low (40%) relative humidities. Roots stored at 40% relative humidity dehydrated significantly and their respiration rate was accelerated during 28 days of storage. The increase in root respiration during storage at low relative humidity was closely associated with weight loss. Raffinose concentrations increased significantly during storage at high relative humidity but decreased in dehydrated roots. There was an increase in myo-inositol and a decrease in galactinol levels during storage at both high and low relative humidity. A slight decrease in stachyose level was found in stored roots. The observed decrease in raffinose levels in dehydrated roots could be due to its degradation to melibiose and myo-inositol, as they increased in dehydrated roots. The results suggest that low storage relative humidity can alter the postharvest physiology of sugarbeet roots by increasing weight loss, accelerating root respiration rate, and influencing raffinose metabolism. Roots also became soft and visibly wilted upon dehydration, which could affect root processing and sucrose yield.