Phylotranscriptomic profiling of the Arabidopsis life cycle, organogenesis, and the cell cycle

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The developmental hourglass model is one of the classic concepts in developmental biology. In animals, embryos from various taxa from a common phylum appear different in early stages, converge to a similar form during mid embryogenesis, and again diverge in later stages of embryo development. This morphogenetic series is known as the developmental hourglass and is based on observations by Karl Ernst von Baer from the early 19th century. Recent studies in several animal species showed that global gene expression profiles also followed an hourglass pattern, providing convincing molecular support for the developmental hourglass model. Although plants also evolved embryogenesis, the developmental hourglass concept had not been addressed in the plant kingdom. By combining phylogenetics and transcriptomics (phylotranscriptomics), we could recently demonstrate the existence of a phylotranscriptomic hourglass pattern for Arabidopsis embryogenesis, suggesting a fundamental mechanism controling global gene expression profiles across kingdoms.Based on fundamental differences in plant and animal development, we hypothesize that the developmental hourglass pattern might not be restricted to embryogenesis, but might be a general characteristic of developmental processes. Exploiting the predominantly post-embryonic nature of plant development (in contrast to most animals) offers experimental opportunities to assess the general existence of phylotranscriptomic patterns in several important developmental processes. In this interdisciplinary project, we seek to address this hypothesis on three different spatio-temporal levels. Using the Arabidopsis model system we plan to perform phylotranscriptomic studies of (i) the life cycle of complete plants, (ii) organogenesis from early meristematic activities to the mature differentiated organ, and (iii) the cell cycle. Based on the emerging phylotranscriptomic patterns, we aim to identify pattern-shaping genes and putative cis-regulatory modules controling their activities. Together, our objective is to generate data sets that are of general interest for the plant community and take a first step toward understanding the observed phylotranscriptomic patterns.