Regulation of Soybean Embryogenesis by Abscisic Acid

Abstract

Abscisic Acid (ABA) stimulates growth and protein accumulation in soybean (Glycine max. L. Merr.) embryos during the early phases of embryogenesis. Growth of mid-stage embryos is suppressed by ABA, but protein accumulation is not impaired. Metabolite distribution studies indicate that ABA alters partitioning of sucrose in older embryos such that protein accumulation is sustained at the expense of lipid accumulation. The responses of in vitro cultured embryos to ABA is consistent with the normal pattern of ABA accumulation and disappearance that occurs during embryogenesis in situ. A close correlation exists between ABA levels and embryo growth rates in situ in three cultivars of soybeans. Depending on the age or stage of the developing embryo, ABA either serves to promote or inhibit embryo growth.