PLANT PHYSIOLOGY , Vol 113, Issue 2 403-409, Copyright © 1997 by American Society of Plant Biologists
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GENE REGULATION AND MOLECULAR GENETICS |
Characterization of a Maize [beta]-Amylase cDNA Clone and Its Expression during Seed Germination
S. M. Wang, W. L. Lue, S. Y. Wu, H. W. Huang and J. Chen
Department of Botany, National Taiwan University, Taipei, Taiwan (S.-M.W., S.-Y.W., H.-W.H.)
A maize (Zea mays L.) cDNA clone (pZMB2) encoding [beta]-amylase was
isolated from a cDNA library prepared from the aleurone RNA of germinating
kernels. The cDNA encodes a predicted product of 488 amino acids with
significant similarity to known [beta]-amylases from barley (Hordeum
vulgare), rye (Secale cereale), and rice (Oryza sativa). Glycine-rich
repeats found in the carboxyl terminus of the endosperm-specific
[beta]-amylase of barley and rye are absent from the maize gene product.
The N-terminal sequence of the first 20 amino acids of a [beta]-amylase
peptide derived from purified protein is identical to the 5th through 24th
amino acids of the predicted cDNA product, indicating the absence of a
conventional signal peptide in the maize protein. Recombinant inbred
mapping data indicate that the cDNA clone is single-copy gene that maps to
chromosome 7L at position 83 centimorgans. Northern blot analysis and in
vitro translation-immunoprecipitation data indicate that the maize
[beta]-amylase is synthesized de novo in the aleurone cells but not in the
scutellum during seed germination.
