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ARS Home » Research » Publications at this Location » Publication #62770
Title: CHANGES IN SOLUBLE CARBOHYDRATES AND ENZYMATIC ACTIVITIES IN MATURING SOYBEAN SEED TISSUES

Author
item Kuo, Tsung Min
item LOWELL, CADANCE - CENTRAL STATE UNIV, OHIO
item SMITH, PATRICK - NIH, BETHESDA, MD

Submitted to: Plant Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/14/1997
Publication Date: N/A
Citation: N/A

Interpretive Summary: Soybean seed contains up to 6% by dry weight of anti-nutritional sugars. We identified physical traits of field-grown seeds that coincided with the formation and accumulation of these sugars. During seed maturation, we also measured the enzyme activities involved in the formation and breakdown of these sugars. As a result, we have determined the location and interactions of these enzymes in the seed as related to the accumulation o anti-nutritional sugars. This information will be useful for researchers to reduce anti-nutritional factors and subsequently improve both the nutritional and market value of soybeans.

Technical Abstract: Associated metabolic enzyme activities were compared with the accumulation of soluble carbohydrates and starch in seed coats, cotyledons and embryonic axes of field-grown soybean (Glycine max L. Merr. cv Williams 82) seeds to examine the function of each seed tissue in non-structural carbohydrate metabolism. The vascularized seed coat was comparatively high in monosaccharides (glucose, fructose) which corresponded to greater acid invertase activity per gram dry weight. The embryo (cotyledon + embryonic axis) was highest in oligosaccharide and starch content, and greater mean activity levels of sucrose synthase, alkaline invertase, galactinol synthase and a-galactosidase. There was little difference in the sucrose- phosphate synthase activity among these three tissues. Pinitol, previously uncharacterized in soybean seed tissues, was present as one of the major non-structural carbohydrates during seed development. The accumulation of raffinose saccharides (raffinose and stachyose) increased as starch content decreased in the embryo. Activities of alkaline invertase, sucrose synthase, galactinol synthase, a-galactosidase, fructose-1, 6-bisphosphate aldolase, malate dehydrogenase, and glucose-6-phospate dehydrogenase were highest in embryonic axes. Initial maturation of the developing soybean seed may be distinguished morphologically. These changes were found to coincide with increases in sucrose synthase and galactinol synthase activities, initial decreases in starch content and fresh weight, and initial accumulation of raffinose saccharides in the embryonic axis.