PLANT PHYSIOLOGY , Vol 106, Issue 4 1471-1481, Copyright © 1994 by American Society of Plant Biologists
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MOLECULAR BIOLOGY AND GENE REGULATION |
Characterization and Expression of an Antifungal Zeamatin-like Protein (Zlp) Gene from Zea mays
D. E. Malehorn, J. R. Borgmeyer, C. E. Smith and D. M. Shah
The Agricultural Group, Monsanto Company, 700 Chesterfield Village Parkway, St. Louis, Missouri 63198
A cDNA clone encoding a basic thaumatin-like protein of Zea mays was
recovered from a mid-development seed cDNA library. The gene, Zlp, encoded
a protein that was nearly identical with maize zeamatin and
[alpha]-amylase/trypsin inhibitor. Expression of Zlp mRNA was highest in
the endosperm tissue of seed 4 weeks after pollination. Expression of
zeamatin-like (ZLP) protein correlated with mRNA; also, a low basal level
of ZLP expression in leaf was not appreciably induced by abiotic stresses.
ZLP was expressed with its own signal peptide in insect cells and in
transgenic Arabidopsis and tomato plants. ZLP was secreted in all three
systems, with correct processing of the signal peptide. ZLP expressed in
transgenic tomato was found to be partially subjected to a proteolytic
cleavage after residue 180, by an unknown mechanism, to give a "nicked"
isoform of ZLP. Purified ZLP from all three sources, as well as purified
"nicked" ZLP from tomato, demonstrated fungal inhibition against Candida
albicans and Trichoderma reesei, with marginal inhibition observed against
Alternaria solani and Neurospora crassa.
