Silencing of an anther-specific zinc-finger gene, MEZ1, causes aberrant meiosis and pollen abortion in petunia

MEZ1 (M Eiosis-associated Zinc-finger protein 1) was first isolated as an anther-specific cDNA from Petunia hybrida. In the present study, we report its functional characterization, including its spatial and temporal expression profiles and phenotypes in MEZ1-silenced plants. MEZ1 transcripts were specifically localized in pollen mother cells during early stages of anther development, and were later distributed in vegetative tissues in anthers. Silencing of MEZ1 by cosuppression resulted in several anomalies during male meiosis that included inability of chromosomes to condense, loss of meiotic synchrony, and premature and apparently uncontrolled cytokinetic events. Consequently, by the end of meiosis 8-10 cells, instead of the normal 4, with varying DNA contents were formed in the MEZ1-silenced meiocytes. Most of these aborted prematurely, and those that matured had a distinctive morphology. MEZ1-silenced plants were female sterile when pollinated with wild-type pollen but they infrequently produced a few seeds upon self-pollination. Resulting T-1 plants had increased ploidy levels and exhibited severe anomalies during male meiosis, rendering them completely sterile. We discuss possible role of MEZ1 in the proper progression of plant meiosis.