A TM3-like MADS-box gene from Eucalyptus expressed in both vegetative and reproductive tissues

MADS-box genes in plants are a diverse class of transcription factors that are involved in regulating developmental processes, particularly meristem a nd organ identity during floral development. They are characterized by a hi ghly conserved MADS-box domain of 59 amino acids that binds to specific DNA sequences. We report the characterization of a cDNA clone, ETL (Eucalyptus TM3 Like), from Eucalyptus globulus subspecies bicostata encoding a putati ve transcription factor of the MADS-box class that is strongly expressed in both vegetative and floral tissues, suggesting that it regulates processes other than floral development. The clone was isolated from a floral bud cDNA library with a probe generate d from Eucalyptus genomic DNA by PCR using degenerate primers to the MADS-b ox of the floral regulatory gene APETALA 1. The ETL cDNA clone encodes a pu tative protein of 206 amino acids that contains an N-terminal MADS-box and a helical domain of approx. 60 amino acids predicted to form a coiled-coil (K-box). These structural features are characteristic of plant MADS-box pro teins. The MADS-box domain contains all the signature residues of a class o f MADS-box genes typified by the tomato gene TM3 and overall, ETL shows 56% amino acid identity to TM3. Like TM3, the ETL gene is expressed in both ve getative and reproductive organs, predominantly in root and shoot meristems and organ primordia, as well as in developing male and female floral organ s. (C) 1999 Elsevier Science B.V. All rights reserved.