Plant reproductive development has been the subject of intensive investigation in recent years, and members of the MADS-box family of regulatory genes have been shown to control key aspects of this complex process. The carpels and resulting fruit are arguably the most complex plant organs, and the AGAMOUS (AG) clade of MADS-box genes is necessary for carpel and fruit development. There are four closely related genes within this monophyletic clade, including AG, SHATTERPROOF1 (SHP1), SHP2 and AGL11. The AG gene, which encodes the C function of the widely-recognized ABC model of flower organ identity, is necessary for carpel identity. The SHP genes act redundantly during fruit development to specify differentiation of the dehiscence zone, a process that is required for seed dispersal. Mutant alleles for AGL11, the final member of this important clade of genes have been isolated. The initial analyses of agl11 mutants demonstrate that AGL11 is required for normal ovule and seed development, and for the normal process of seed dispersal. Moreover, when mutations in AGL11 are combined with mutations in both SHP1 and SHP2, ovule development is completely abolished. These studies indicate that AGL11, SHP1 and SHP2 act redundantly to specify ovule identity. With agl11-mutant alleles in hand, the next step is not only to define the roles of AGL11 during ovule/carpel/seed/fruit development, but to fully dissect the individual and redundant activities of the AG clade of genes. These studies should have far-reaching implications for the study of similar developmental processes in diverse plant species. Initial studies will focus on a detailed description of the agl11 and agl11 shp1 shp2 mutant phenotypes. Unstable alleles of AG will be made in order to fully explore the individual and overlapping activities of AG with the other members of this gene clade. Interactions will be explored between AGL11 and the other AG-clade genes with the many known genes involved in ovule and carpel development. These studies will involve the introduction of mutant alleles for these ovule/carpel development genes into the agl11 and agl11 shp1 shp2 mutant backgrounds. In parallel with these genetic studies, the expression of AGL11 RNA will be monitored in each of these mutants and we will monitor the expression of each of the ovule/carpel development genes in the agl11 and agl11 shp1 shp2 backgrounds. Together these studies should provide a conceptual framework for understanding the genetic and molecular interactions that underlie ovule/carpel/seed/fruit development in Arabidopsis.
