Effect of Abscisic Acid on Amino Acid Uptake and Effiux in Developing Soybean Seeds1
- Steven J. Guldan and
- William A. Brun2
The role of abscisic acid (ABA) in regulating growth of developing soybean [Glycine max (L.) Merr.] seeds is not fully understood. The objectives of this study were to characterize the effect of ABA on the in vitro uptake of asparagine and glutamine by isolated immature cotyledons in three soybean plant introduction (PI) lines with genotypic differences in seed growth rate and final seed weight. Cotyledons were incubated in uptake buffer solutions plus 14C-asparagine or 14C-glutamine and treatment concentrations of ABA. The ABA levels in the uptake solutions were 0, 10-7, 10-6, and 10-5 M. The uptake rate of glutamine was approximately three times that of asparagine. Among PI lines, the heavy seeded line had a greater rate of asparagine uptake while the light seeded line had a greater rate of glutamine uptake. For asparagine, 10-6 M ABA depressed uptake compared to the control. For glutamine, ABA enhanced uptake compared to the control at both 10-6 and 10-5 M. In an additional experiment, we observed no effect of ABA and K+ on the release of labeled asparagine from excised soybean seed coats. These data indicate that amino acid uptake rates are genotypically dependent and may be influenced by ABA concentration.Please view the pdf by using the Full Text (PDF) link under 'View' to the left.
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