Formation and Degradation of Storage Proteins in the Embryo of Sinapis alba

Abstract

The synthesis and accumulation of storage proteins of Sinapis alba was shown in a continuous line of SDS gels during the development of embryos up to maturation. The synthesis for the large storage protein (13 s) starts at day 14 after pollination and stops 34 days after pollination. The small protein (1.7s) is synthesized up to the full maturation of the seeds. The phase of storage protein synthesis is not coordinated with the change in water status in the developing seeds or embryos. Freshly isolated embryos can germinate but are able to continue storage protein synthesis for at least 10 hours after isolation when they are younger than 35 days. This synthesis can be stimulated slightly by treatment with 1μM ABA. Embryos older than 40 days do not synthesize the large storage protein, and the synthesis can not be induced with 1μM ABA under the conditions of germination. This external ABA concentration, however, delays the degradation of storage proteins during germination by about 2 days in mature and 4 days in immature embryos. The appearance of the pattern of the newly formed «germination proteins» is retarded by the same time.