|De Los Reyes, Benildo|
|Mcgrath, J Mitchell - Mitch|
Submitted to: American Society of Sugarbeet Technologists
Publication Type: Abstract Only
Publication Acceptance Date: 9/5/2002
Publication Date: N/A
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 alpha-amylase in a poor-emerging sugarbeet cultivar. In contrast, a good-emerging variety exhibited only a moderate reduction in alpha-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 supplement to reduced carbohydrate catabolism, the good-emerging, but not the poor-emerging, variety appeared to catabolize lipids for use in 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. The differential activity of the glyoxylate cycle is another potential physiological marker to differentiate between high- and low-vigor sugarbeet cultivars.