THE PLANT CELL, Vol 1, Issue 11 1079-1093, Copyright © 1989 by American Society of Plant Biologists
Kunitz Trypsin Inhibitor Genes Are Differentially Expressed during the Soybean Life Cycle and in Transformed Tobacco Plants
K. D. Jofuku and R. B. Goldberg
Department of Biology, University of California, Los Angeles, California 90024-1606
We investigated the structure, organization, and developmental regulation
of soybean Kunitz trypsin inhibitor genes. The Kunitz trypsin inhibitor
gene family contains at least 10 members, many of which are closely linked
in tandem pairs. Three Kunitz trypsin inhibitor genes, designated as KTi1,
KTi2, and KTi3, do not contain intervening sequences, and are expressed
during embryogenesis and in the mature plant. The KTi1 and KTi2 genes have
nearly identical nucleotide sequences, are expressed at different levels
during embryogenesis, are represented in leaf, root, and stem mRNAs, and
probably do not encode proteins with trypsin inhibitor activity. By
contrast, the KTi3 gene has diverged 20% from the KTi1 and KTi2 genes, and
encodes the prominent Kunitz trypsin inhibitor found in soybean seeds. The
KTi3 gene has the highest expression level during embryogenesis, and is
also represented in leaf mRNA. All three Kunitz trypsin inhibitor genes are
regulated correctly in transformed tobacco plants. Our results suggest that
Kunitz trypsin inhibitor genes contain different combinations of
cis-control elements that program distinct qualitative and quantitative
expression patterns during the soybean life cycle.
