A cDNA, MZm3-3, was isolated by differential screening of a cDNA library fr
om Zea mays meiotic stage anthers against cDNA of 3-week-old seedlings. Cha
racterization of this cDNA indicated that the MZm3-3 gene is expressed spec
ifically during male gametogenesis. Its expression is highly and preferenti
ally detected in the tapetum, from the pollen mother cell to uninucleated m
icrospore stages. It encodes a short alkaline protein of 10.6 kDa, with a c
onserved pattern of eight cysteine residues. Sequence analysis showed that
these features are shared with lipid transfer proteins and some male-flower
-specific proteins. The presence of a putative signal peptide indicates tha
t MZm3-3 enters into the secretory pathway to then be released into the ant
her loculus. Based on these features, the secretory activity of the tapetum
and the temporal expression pattern of MZm3-3, a contribution to pollen co
at formation is suggested. Southern blot analyses demonstrated the presence
of closely related genes, indicating that MZm3-3 belongs to a multigene fa
mily. (C) 2000 Elsevier Science Ireland Ltd. All rights reserved.