ARS | Publication request: GASA4, One of the 14-Member Arabidopsis GASA Family of Small Polypeptides, Regulates Flowering and Seed Development

Submitted to: Plant And Cell Physiology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: January 10, 2007
Publication Date: February 6, 2007
Repository URL: http://pcp.oxfordjournals.org/cgi/reprint/48/3/471
Citation: Roxrud, I., Lid, S., Fletcher, J.C., Opsahl-Sorteberg, H.-G., Schmidt, E. 2007. GASA4, One of the 14-Member Arabidopsis GASA Family of Small Polypeptides, Regulates Flowering and Seed Development. Plant And Cell Physiology. 48(3):471-483.

Interpretive Summary: The GASA gene family consists of a group of hormone-responsive, plant-specific small polypeptides. We identified 6 new Arabidopsis GASA genes and delineated the common structural features of the family members. We examined the expression of 6 GASA genes and found that they are produced in many tissues in the plant, in overlapping patterns. We determined that GASA4 activity promotes the formation of flowers instead of secondary stems, and increases seed size and weight. Our results demonstrate that members of the GASA gene family are important for regulating plant development, in addition to the structural roles indicated by previous studies.

Technical Abstract: Members of the plant-specific gibberellic acid-stimulated Arabidopsis (GASA) gene family play roles in hormone response, defense and development. We have identified six new Arabidopsis GASA genes, bringing the total number of family members to 14. Here we show that these genes all encode small polypeptides that share the common structural features of an N-terminal putative signal sequence, a highly divergent intermediate region and a conserved 60 amino acid C-terminal domain containing 12 conserved cysteine residues. Analysis of promoter::GUS (ß-glucuronidase) transgenic plants representing six different GASA loci reveals that the promoters are activated in a variety of stage- and tissue-specific patterns during development, indicating that the GASA genes are involved in diverse processes. Characterization of GASA4 shows that the promoter is active in the shoot apex region, developing flowers and developing embryos. Phenotypic analyses of GASA4 loss-of-function and gain-of-function lines indicate that GASA4 regulates floral meristem identity and also positively affects both seed size and total seed yield.