About sisters and starlets : Bsister and MIKC* type MADS box genes in rice development I investigate the function and evolution of different rice MIKC type MADS box genes which due to their high variety and significance in plant development are excellent objects to study the outcome of gene duplications. Bsister MADS box genes are known for their predominant role in plant female organ development. The rice Bsister gene OsMADS29 confers the ‘canonical’ Bsister function in rice. With a detailed comparative meta analysis of all available Bsister gene expression patterns I underline the significance of OsMADS29 like genes within grass ovule and seed development. These genes are all very strongly and more or less exclusively expressed during ovule and or seed development thus resembling eudicot and gymnosperm Bsister gene expression patterns. I further performed a detailed analysis of the rice gene OsMADS30 showing that it is a non canonical Bsister gene: it has a comparatively weak and broad expression and T DNA insertion lines show no aberrant seed phenotype. I further demonstrated that OsMADS30 evolved under relaxed purifying selection and has a 3’ region that strongly deviates from other grass Bsister genes including closely related OsMADS30 orthologs from wild rice species. This is due to the recent insertion of a hitherto unknown transposable element. T DNA insertion lines of OsMADS30 show diminished vegetative growth which might be first evidence for a neo functionalization of OsMADS30. I also studied MIKC* type MADS domain proteins that function in pollen development: OsMADS62 OsMADS63 and OsMADS68. I demonstrate that they bind not as homodimers but only as heterodimers to DNA. This thesis contributes to a deeper understanding of the developmental and evolutionary significance of various rice MADS box genes. Eventually it shows how fundamentally different the results of gene duplications even within the same gene family can turn out.