Phylotranscriptomics of the carpel developmental toolkit - an evo-devo study towards understanding the origin of flowering plants

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Carpels (female reproductive organs of flowering plants) are of major economic importance as most of our food is ultimately derived from carpel tissue and they are a defining innovation for flowering plants. The evolutionary origin of the carpel is a fundamental yet unresolved developmental innovation contributing to the origin of angiosperms. Amazingly, little is known about the origin and conservation of the developmental program of the carpel besides the knowledge generated by utilizing Arabidopsis thaliana. Our research would address critical questions about the origin and evolution of gene interaction network controlling carpel development in diverse angiosperm lineages. For example, we will determine whether genes contributing to carpel development originated with the angiosperms or predated the origin of angiosperms in the ancestral angiosperm. If the former, we will elucidate how angiosperm-specific carpel development genes originated and evolved over angiosperm history and how the carpel developmental gene network has diversified across major angiosperm lineages. We will deepen our fundamental understanding of carpel development and evolution through comparative analysis of transcriptomes from carpels and female cones of gymnosperms, the sister group to angiosperms across different developmental stages in a wide range of phylogenetically informative and economically important species including the angiosperms Amborella trichopoda (most basal angiosperm), Arabidopsis thaliana (thale cress, core eudicot model organism), Eschscholzia californica (basal eudicot), Oryza sativa (rice, monocot), Solanum lycopersicum (tomato, core eudicot), and the gymnosperms Picea abies (Norway spruce, conifer), and Welwitschia mirabilis (gnetales). In order to gain a precise understanding of the spatial and temporal dynamics of gene expression in carpel development, we will employ Laser Capture Microdissection. Non-standard comparative transcriptome analysis will be performed to identify a set of core genes utilized for carpel development in the majority of species in an unbiased way. We will compare in several dimensions: (i) across different carpel developmental stages, (ii) between leaf and carpel tissue, (iii) across angiosperms and two gymnosperms to extract our candidate genes specifically from non-model plant organisms. Functional analyses by observing knock-out and knock-down phenotypes will be performed on genes implicated as most important for carpel initiation and development. This work will reveal novel, highly conserved carpel development regulators that were the prerequisite for the carpel, and thus angiosperm origin and which might also prove useful for crop optimization in the long run.