THE PLANT CELL, Vol 1, Issue 11 1095-1109, Copyright © 1989 by American Society of Plant Biologists
Soybean Seed Protein Genes Are Regulated Spatially during Embryogenesis
L. Perez-Grau and R. B. Goldberg
Department of Biology, University of California, Los Angeles, California 90024-1606
We used in situ hybridization to investigate Kunitz trypsin inhibitor gene
expression programs at the cell level in soybean embryos and in transformed
tobacco seeds. The major Kunitz trypsin inhibitor mRNA, designated as KTi3,
is first detectable in a specific globular stage embryo region, and then
becomes localized within the axis of heart, cotyledon, and maturation stage
embryos. By contrast, a related Kunitz trypsin inhibitor mRNA class,
designated as KTi1/2, is not detectable during early embryogenesis. Nor is
the KTi1/2 mRNA detectable in the axis at later developmental stages. Outer
perimeter cells of each cotyledon accumulate both KTi1/2 and KTi3 mRNAs
early in maturation. These mRNAs accumulate progressively from the outside
to inside of each cotyledon in a "wave-like" pattern as embryogenesis
proceeds. A similar KTi3 mRNA localization pattern is observed in soybean
somatic embryos and in transformed tobacco seeds. An unrelated mRNA,
encoding [beta]-conglycinin storage protein, also accumulates in a
wave-like pattern during soybean embryogenesis. Our results indicate that
cell-specific differences in seed protein gene expression programs are
established early in development, and that seed protein mRNAs accumulate in
a precise cellular pattern during seed maturation. We also show that seed
protein gene expression patterns are conserved at the cell level in embryos
of distantly related plants, and that these patterns are established in the
absence of non-embryonic tissues.
