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Plant Physiology 76:301-306 (1984) © 1984 American Society of Plant Biologists Abscisic Acid and Its Relationship to Seed Filling in Soybeans 1Department of Horticultural Science and Landscape Architecture, University of Minnesota, St. Paul, Minnesota, 55108, Department of Agronomy and Plant Genetics, University of Minnesota, St. Paul, Minnesota, 55108
The effect of exogenous abscisic acid (ABA) on the rate of sucrose uptake by soybean (Glycine max L. Merr.) embryos was evaluated in an in vitro system. In addition, the concentrations of endogenous ABA in seeds of three soybean Plant Introduction (PI) lines, differing in seed size, were commpared to their seed growth rates. ABA (107 molar) stimulated in vitro sucrose uptake in soybean (cv `Clay') embryos removed from plants grown in a controlled environment chamber, but not in embryos removed from field-grown plants of the three PI lines. However, the concentration of ABA in seeds of the three field-grown PI lines correlated well with their in situ seed growth rates and in vitro [14C] sucrose uptake rates. Across genotypes, the concentration of ABA in seeds peaked at 8.5 micrograms per gram fresh weight, corresponding to the time of most rapid seed growth rate, and declined to 1.2 micrograms per gram at physiological maturity. Seeds of the large-seeded genotype maintained an ABA concentration at least 50% greater than that of the small-seeded genotype throughout the latter half of seed filling. A higher concentration of ABA was found in seed coats and cotyledons than in embryonic axes. Seed coats of the large-seeded genotype always had a higher concentration of ABA than seed coats of the small-seeded line. It is suggested that this higher concentration of ABA in seed coats of the large-seeded genotype stimulates sucrose unloading into the seed coat apoplast and that ABA in cotyledons may enhance sucrose uptake by the cotyledons.
1 Supported in part by the United States Department of Agriculture under grant 82-CRCR-1-1077 from the Competitive Research Grants Office. Also supported in part by a grant from the Minnesota Soybean Research and Promotion Council. Contribution from the University of Minnesota Agricultural Experiment Station, St. Paul, MN 55108. Paper No. 13764, Scientific Journal Series. This article has been cited by other articles:
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