|DE LOS REYES, BENILDO|
Submitted to: American Society of Beet Sugar Technologists Proceedings
Publication Type: Proceedings
Publication Acceptance Date: 3/1/2003
Publication Date: 6/30/2003
Citation: De Los Reyes, B., Mcgrath, J.M. 2003. Differential expression of glyoxylate cycle enzymes in sugar beet is related to genotypic variation under stress germination.. American Society of Beet Sugar Technologists Proceedings. p. 405-408.
Technical Abstract: One component of seedling vigor is the efficient utilization of the seed storage reserves to provide energy necessary for growth. This study examined the relationship between the genes of energy metabolism and differences in seedling vigor of sugar beet hybrids under different stress germination regimes. Analyses of 1,718 5' Expressed Sequence Tags (ESTs) from subtracted cDNA libraries, combined with gene expression profiling by northern blots and enzyme activity assays indicated that stress drastically reduces the expression of a beta-amylase in a poor-emerging sugarbeet cultivar. In contrast, a good emerging variety exhibited only a moderate reduction in beta-amylase gene expression. This pattern of gene expression indicates that mobilization of energy from stored carbohydrates can be limited to various extents by abiotic stresses. As a mechanism to cope with reduced carbohydrate catabolism, the good-emerging, but not the poor-emerging, variety appeared to catabolize lipids as a supplementary source of energy for respiration and biosynthetic processes. Induction of glyoxylate cycle activity, whose pathway bridges lipid and carbohydrate metabolism in germinating seeds, was indicated by high transcript levels and increased enzyme activity for the key glyoxylate cycle enzymes isocitrate lyase and malate synthase. This is the first report of differential activity of the glyoxylate cycle as a potential physiological marker to differentiate between high- and low-vigor sugarbeet cultivars.