Immunocytochemical localization of the storage protein phaseolin in the embryo-suspensor of Phaseolus coccineus.

ABSTRACT

Antibodies against the bean storage protein, phaseolin, were induced in rabbits. Sections of bean embryos of various age were incubated with the antibodies, and exposed to fluorescein isocyanate (FITC) conjugated goat anti-rabbit immunoglobulin. Distinct positive signals were found in vacuoles of the suspensor giant cells. Immunofluorescent staining of protein bodies in cotyledon cells, histochemical staining reactions of the sections, as well as gel electrophoretic analysis of the proteins, isoelectric focusing and Western blotting confirmed the specificity and reliability of the immunochemical staining of the suspensor cells. The results give evidence for synthesis of storage proteins in the embryo-suspensor and indicate a function so far not detected of this embryonal nutritive organ.