Gene structure and molecular analysis of Arabidopsis thaliana ALWAYS EARLY homologs

Drosophila always early (aly) is essential for spermatogenesis, and is related to the LIN-9 protein of Caenorhabditis elegans; lin-9 is a class B Synthetic Multivulva gene (synMuvB) required for gonadal sheath development. Aly/LIN-9 have two conserved regions, called domains 1 and 2, which have been identified in homologous proteins from several multicellular eukaryotes, including the model plant Arabidopsis thaliana. We cloned and sequenced cDNAs of three different A. thaliana ALWAYS EARLY homologs (AtALY1, AtALY2 and AtALY3), analysed the expression pattern of these three genes and show that AtALY1, like Aly, is nuclear localised. We also demonstrate that the plant homologs of aly/lin-9 contain an additional N-terminal myb domain not present in the animal Aly/LIN-9 proteins, and that part of the ALY/LIN-9 conserved domain 1 in the predicted plant proteins is related to the TUDOR domain.