Developmental gene expression in conifer embryogenesis and germination. II. Crystalloid protein synthesis in the developing embryo and megagametophyte of white spruce ( Picea glauca [Moench] Voss.)

Abstract

We have followed the synthesis and accumulation of soluble matrix and insoluble crystalloid proteins during development of the zygotic embryo of white spruce ( Picea glauca [Moench] Voss.). SDS-PAGE and immunoblot analysis demomstrated that crystalloids, the major proteins in the mature seeds, can be detected in the haploid megagametophyte as early as two to three days after fertilization, and accumulate to high levels during mid-and late stages of embryogenesis. In the diploid embryonic axes, crystalloid proteins could be detected in the early stages of development, when it was possible to physically separate the embryo from the megagametophyric tissue. Analysis of the protein extracts from each of the tissues by gel electrophoresis revealed differential accumulation of their component polypeptides. The 35 kD-range polypeptides made up a relatively higher proportion of total crystalloids at the early stages. Electrophoresis of the soluble matrix fraction showed that the major group of polypeptides appeared at the same stage of development as did the crystalloids. Also, there was a temporal variation in the accumulation of different polypeptides of the major storage proteins in the soluble fraction.