Identification and characterization of storage proteins in zygotic and somatic embryos of geranium (Pelargonium x hortorum)

Abstract

Storage proteins in zygotic and somatic embryos of 'Scarlet Orbit Improved', zonal geranium (Pelargonium x hortorum L.H. Bail.) were identified and characterized using gel electrophoresis. The major seed storage proteins in zygotic embryos were an 11S globulin and two low molecular weight (LMW1.2) proteins. The 11S globulin consisted of four distinct subunits (53-74 ku), with each subunit being composed of an acidic polypeptide (A1-A4; 28-44 ku) linked via disulphide bonds to a basic polypeptide (B1-B4; 20-25 ku) and was named pelargin. The LMW (15.5 and 12,5 ku) albumins were not linked with disulphide bonds. Mature somatic embryos contained 80% of the proteins in zygotic embryos. Although protein profiles were more distinct in mature somatic embryos compared to nonmature, none of the zygotic embryo storage protein was present in the somatic embryos, indicating lack of complete maturity of somatic embryos. This study identified zygotic embryo proteins and demonstrated that maturation of somatic embryos improves protein content and types of proteins.