Characterization of MZm3-3, a Zea mays tapetum-specific transcript

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.