Sex Plant Reprod (2004) 17: 189–193 DOI 10.1007/s00497-004-0230-z ORIGINAL ARTICLE Sachihiro Matsunaga . Wakana Uchida . Eduard Kejnovsky . Erika Isono . Francoise Moneger . Boris Vyskot . Shigeyuki Kawano Characterization of two SEPALLATA MADS-box genes from the dioecious plant Silene latifolia Received: 30 March 2004 / Accepted: 4 August 2004 / Published online: 1 September 2004 # Springer-Verlag 2004 Abstract Two SEPALLATA orthologs, SlSEP1 and SlSEP3, were isolated from male flower buds of the dioecious plant Silene latifolia. Both genes are located on autosomes and not on the sex chromosomes. SlSEP1 and SlSEP3 transcripts were detected specifically in male and female flower buds. Quantitative RT-PCR and in situ hybridization revealed that both genes were expressed in young flower meristems, developing petals, male anthers, and female ovules. However, neither transcript was detected in suppressed gynoecia of male flower buds or suppressed anthers of female flower buds. The genes were differentially expressed during anther development, with the SlSEP1 transcript accumulating in anther walls and tapetal cells, and the SlSEP3 transcript accumulating in tetrads as well as anther walls and tapeta. Transcripts of both genes were also detected in flower buds of mutants with deletions of some parts of the Y chromosome, suggesting that neither gene is directly involved in sex determination. Keywords Dioecious plant . SEPALLATA . Petal . Ovule . Pollen grains Introduction The Arabidopsis thaliana genes SEPALLATA 1, 2, and 3 (SEP1, 2, and 3) were identified as AGAMOUS-like genes AGL 2, 4, and 9, which are preferentially expressed in floral organs (Mandel and Yanofsky 1998; Ma et al. 1991). Analysis of triple mutants of the SEP genes revealed that these genes are required for the development of petals, stamens, and carpels (Pelaz et al. 2000). According to the quartet model of floral organ specification, floral organs in A. thaliana, including sepals, petals, stamens, and carpels, are determined by four combinations of floral homeotic proteins, most of which are known as MADS-box proteins (Theissen and Saedler 2001). The expression of class B genes and a class C gene in combination with SEP genes specifies stamen identity, whereas the expression of a class C gene and SEP genes specifies carpel identity (Honma and Goto 2001). SEP genes are abundantly expressed in developing petals, stamens, and carpels, and even more highly in developing ovules (Flanagan and Ma 1994; Savidge et al. 1995; Mandel and Yanofsky 1998). It has recently been shown that SEP proteins are necessary for the formation of transcription factor complexes that control ovule development (Favaro et al. 2003). Electronic Supplementary Material Supplementary material is available in the online version of this article at http://dx.doi. org/10.1007/s00497-004-0230-z S. Matsunaga (*) . W. Uchida . S. Kawano Department of Integrated Biosciences, Graduate School of Frontier Sciences, University of Tokyo, 5–1–5 Kashiwanoha, Kashiwa, 277–8562 Chiba , Japan e-mail: sachi@bio.eng.osaka-u.ac.jp Fax: +81-6-68797441 E. Kejnovsky . B. Vyskot Institute of Biophysics, Academy of Sciences of the Czech Republic, 612 65 Brno, Czech Republic E. Isono Department of Biological Sciences, Graduate School of Science, University of Tokyo, Hongo, 113–0033 Tokyo , Japan F. Moneger Reproduction and Developmental Biology, Ecole Normale Superieure de Lyon, Lyon, France Present address: S. Matsunaga Department of Biotechnology, Graduate School of Engineering, Osaka University, 2–1 Yamadaoka, Suita, 565–0871 Osaka , Japan Present address: W. Uchida Molecular Membrane Biology Laboratory, RIKEN, 2–1 Hirosawa, Wako, 351–0198 Saitama , Japan