Antisense inhibition of a tomato meiotic proteinase suggests functional redundancy of proteinases during microsporogenesis

Anther development in angiosperms culminates in the programmed cell death o f specific tissues to facilitate the release of pollen. Despite a wealth of morphological descriptions of this process, there have been few reports on the regulation of dehiscence or the coordination of events between tissues . We have cloned an anther-specific tomato gene encoding a serine proteinas e that is expressed during meiosis and late microsporogenesis. The conceptu alized tomato meiotic proteinase (TMP) is a member of a family of genes tha t exhibit characteristics of mammalian proprotein convertases. To examine t he role of TMP in microsporogenesis, we generated transgenic plants harbori ng an antisense construct of the gene. Some of these plants produced little or no detectable TMP, yet no phenotypic abnormalities were observed. Zymog ram analyses revealed that multiple proteinases are present in mature anthe rs and that proteinase activity increases as development proceeds. Taken to gether, these data indicate that the role of TMP during microsporogenesis, if any, may be compensated for by other proteinases.