Submitted to: American Society of Sugarbeet Technologists
Publication Type: Abstract Only
Publication Acceptance Date: November 16, 2006
Publication Date: July 2, 2007
Citation: Klotz, K.L., Suttle, J.C. 2007. Ethylene production and its effect on storage respiration rate in wounded and unwounded sugarbeet roots [abstract.] Journal of Sugarbeet Research. 44(3-4):139. Technical Abstract: Ethylene is produced by all seed plants and stimulates respiration in most plant tissues and organs. To understand how this plant hormone may affect postharvest sugarbeet root respiration, a series of experiments were conducted to determine (1) the rate of ethylene production in wounded and unwounded roots, (2) the effect of exogenous ethylene on root respiration rate, and (3) the effect of ethylene synthesis and response inhibitors on the storage respiration rate of wounded and unwounded roots. All experiments were conducted at 10oC. For the wound treatment, roots were severely bruised and abraded by tumbling in a tare lab beet washer for 30 min. This injury caused a two to three-fold increase in respiration rate in the 48 to 96 h after the injury. Ethylene production by unwounded roots averaged 0.11 nmol kg-1 h-1. In wounded roots, ethylene production averaged 1.30 nmol kg-1 h-1 during the first four days after injury, an eleven-fold increase over unwound roots. Treatment with exogenous ethylene at concentrations of 0.02, 0.1, 1.4 and 14 ppm increased respiration in a dose-dependent manner with respiratory increases ranging from 60% at 0.02 ppm ethylene to 130% at 14 ppm ethylene. At 0.02 and 0.1 ppm ethylene, the increase in respiration was transient, lasting only 48 h. At 1.4 and 14 ppm ethylene, the increase in respiration persisted for at least four days. The ethylene response inhibitor, silver thiosulfate, and the ethylene synthesis inhibitor, aminoethoxyvinylglycine, reduced wound-induced respiration rate by approximately 50%, but did not significantly lower respiration rate in unwounded roots. No consistent effect on sugarbeet root respiration was achieved with the ethylene response inhibitor, 1-methylcyclopropene. These results demonstrate that unwounded sugarbeet roots produce low levels of ethylene, that ethylene synthesis is induced by injury, and that ethylene has a role in the increase in respiration that occurs following injury.