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Relationship Between Decarboxylation of Glutamic Acid and Vigor in Soybean Seed 1
Author(s) -
AbdulBaki Aref A.,
Anderson James D.
Publication year - 1973
Publication title -
crop science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.76
H-Index - 147
eISSN - 1435-0653
pISSN - 0011-183X
DOI - 10.2135/cropsci1973.0011183x001300020023x
Subject(s) - decarboxylation , glutamic acid , imbibition , glycine , glutamate decarboxylase , germination , biochemistry , biology , aspartic acid , amino acid , botany , horticulture , chemistry , enzyme , catalysis
The relationship between seed vigor and decarboxylation of glutamic acid in 16 lots of soybean ( Glycine max L. cv. Lee‐68) was determined (i) manometrically by incubating ground seeds in 75 m M solutions of glutamic acid at pH 5.2 and measuring CO 2 production, and (ii) isotopically by incubating excised embryonic axes in 1 m M glutamic acid‐1‐ 14 C (0.3 µCi/ml) and measuring 14 CO 2 . Both methods agree in that decarboxylation of glutamic acid, presumably by glutamic decarboxylase, was high in both the low‐ and high‐vigor lots. The high decarboxylation of glutamic acid in dry soybean seeds and the low content of glutamic acid in either the imbibed or nonimbibed seed suggest that glutamic acid concentration limits the decarboxylation rate during imbibition. Comparison of total CO 2 produced by whole seeds or seed parts (axes and cotyledons) during early germination with that estimated from glutamic acid decarboxylation suggests that CO 2 production by the tissues via glutamic acid decarboxylation accounts for only a small portion of the CO 2 produced by the seeds. Vigor of the soybean lots is highly correlated with the ability of the excised embryonic axes to incorporate glutamic acid into water‐soluble protein and maintain a relatively high rate of respiration. The decreased 02 uptake and CO 2 production by the low‐vigor lots, pronounced in the axes and negligible in cotyledons, suggests that a search for biochemical indices to measure seed vigor should be focused on embryonic axes rather than on whole seeds.