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Abstract

While the completed genomic sequences of many organisms foster gene discovery, our knowledge of gene functions and regulation is increasingly lagging. Like other eukaryotes, plants are composed of many specific cell types that make function-distinct tissues. How gene expression is precisely controlled and how epigenomic modifications add on the genomic information to regulate transcription locally has eluded analysis so far, mostly because of the poor accessibility of many plant tissues. For example the shoot apical meristem (SAM) that possesses a number of pluripotent stem cells located at the growing tip can produce organs throughout the entire life of plants. At the time of flowering, the SAM of Arabidopsis thaliana switches fate and starts producing flowers instead of leaves. Correct timing of flowering in part determines reproductive success, and is therefore under environmental and endogenous control. Here we report the temporal dynamics of the chromatin modifications H3K4me3 and H3K27me3 and their correlation with transcriptional changes at the SAM in response to photoperiod-induced flowering. Emphasizing the importance of tissue-specific epigenomic analyses we detect enrichments of chromatin states in the SAM that were not apparent in whole seedlings. Furthermore, our results suggest that regulation of translation might be involved in adjusting meristem function during the induction of flowering. In this presentation we also comment on the properties of computational tools that are necessary to uncover the meaningful biological interpretation of obtained high-throughput sequencing data.