Soybean Seed Water Relations during in Situ and in Vitro Growth and Maturation
Open Access
- 1 February 1989
- journal article
- research article
- Published by Oxford University Press (OUP) in Plant Physiology
- Vol. 89 (2), 610-616
- https://doi.org/10.1104/pp.89.2.610
Abstract
Tracerkinetic experiments were performed using l-[guanidino-14C]arginine, l-[U-14C]arginine, l-[ureido-14C]citrulline, and l-[1-14C]ornithine to investigate arginine utilization in developing cotyledons of Glycine max (L.) Merrill. Excised cotyledons were injected with carrier-free 14C compounds and incubated in sealed vials containing a CO2 trap. The free and protein amino acids were analyzed using high performance liquid chromatography and arginine-specific enzyme-linked assays. After 4 hours, 75% and 90% of the 14C metabolized from [guanidino-14C]arginine and [U-14C]arginine, respectively, was in protein arginine. The net protein arginine accumulation rate, calculated from the depletion of nitrogenous solutes in the cotyledon during incubation, was 17 nanomoles per cotyledon per hour. The data indicated that arginine was also catabolized by the arginase-urease reactions at a rate of 5.5 nanomoles per cotyledon per hour. Between 2 and 4 hours 14CO2 was also evolved from carbons other than C-6 of arginine at a rate of 11.0 nanomoles per cotyledon per hour. It is suggested that this extra 14CO2 was evolved during the catabolism of ornithine-derived glutamate; 14C-ornithine was a product of the arginase reaction. A model for the estimated fluxes associated with arginine utilization in developing soybean cotyledons is presented.This publication has 8 references indexed in Scilit:
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