Effect of Short-Term Application of Nitrogen on the Accumulation of β-Subunit of β-Conglycinin in Nitrogen-Starved Soybean(Glycine max L.) Developing Seeds

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It has been reported that the accumulation of the β-subunit of β-conglycinin, a storage protein of soybean (Glycine max L.) seeds, was suppressed by nitrogen (N)-deficiency. In this report we attempted to determine which compound(s) may play a key role in regulating the accumulation of β-subunit mRNA and protein in intact seeds and in an in vitro cotyledon culture system. Non-nodulating soybean plants were cultivated under N-deficient (0.5 mM NO_3^-) conditions, and transferred to N-sufficient medium (5 mM NO_3^-) when the plants reached the pod filling stage. The β-subunit mRNA and the protein were detected in immature seeds within 2 d after transfer to 5 mM NO_3 medium. Among the free amino acids in the immature seeds, asparagine concentration increased rapidly within 2 d. In the in vitro cotyledon culture system, the application of glutamine induced the accumulation of n-sub-unit mRNA within 12 h, while asparagine did not induce the accumulation of β-subunit mRNA for 7 d. An inhibitor of transaminases, (aminooxy)acetic acid, enhanced β-subunit mRNA accumulation without Gln accumulation when asparagine was the sole nitrogen source. Although the asparagine concentration in the seed reflected the nitrogen statues in whole plant, the accumulation of β-subunit mRNA and continuous protein storage in immature seeds appeared to be regulated by glutamine, its metabolites or related compounds.
社団法人日本土壌肥料学会の論文