Conservation of genes and regulatory networks governing carpel development

Abstract

Plants are not only at the basis of most food networks on earth, but are as well a central part of human cultures, as food, feed, medicinal and recreational drugs, and as building material. Flowers are of special interest in the breeding of new varieties, not only for their ornamental value but because fruit and seeds develop from their carpels. Nonetheless, the knowledge of the basis of carpel development is incomplete in many aspects. To broaden the understanding genetic basis of carpel development functional studies by VIGS were combined with phylogenetic calculations, protein-protein-interaction data, and analyses of potential regulating sequences. The experiments were carried out in Eschscholzia californica and the results compared with published data from Arabidopsis thaliana and further species. Aim of this work was to investigate species-spanning mechanisms. Experimental results point to an involvement of the previously unknown genes EcNGA2 and EcSPT2 in style and stigma development, as well as for their paralogues EcNGA1 and EcSPT1. Previously unknown interactions between proteins relevant for carpel development were observed, supporting the idea of different protein core complexes with changing additional interaction partners. Especially dimerizations be- tween MADS and non-MADS proteins are rarely reported in other plant species. Furthermore, a higher number of genes were found to be expressed in the younger carpel stages compared to older ones, resulting in a lower complexity of the protein interaction network in older stages. Based on data from the model plant A. thaliana related genes were identified in E. californica for further studies and analysis of transcription factor binding sites as a tool for examining gene regulation was tested. The examination of the potential regulatory sequences showed no two sequences containing the same binding motives and hence the possibility, that all examined genes are regulated in different ways. Thus it is necessary to know the transcription factors present in the respective tissue and their exact binding motives to identify their target genes. A transfer of binding motives between species seems not feasible. All in all, conserved as well as not-conserved portions where found in the gene regulatory networks between E. californica and A. thaliana. To further explore the similarities and differences further experiments can be conducted based on the foundations laid out here.