Regulatory Circuits Linking Energy Status to Growth

Abstract

Plant growth and development critically depend on carbon nutrient status. Over the past years several core regulatory systems that link plant carbon status to growth have emerged. The core regulatory systems studied include the trehalose 6-phosphate (T6P) signaling system and the Target of Rapamycin (TOR) kinase pathway that both promote growth when activated by the presence of sugars while the SNF1-related Protein Kinase 1 (SnRK1) and the C/S1 bZIP transcription factor network are inhibitory to growth in the absence of sugars. In this research it is investigated how the core regulatory systems interact and how these are linked to the regulation of plant development in Arabidopsis thaliana. Gene regulatory networks are constructed for these systems, using available genomics information in public repositories and novel datasets produced with micro-array and RNA sequencing. Lastly, the connection is investigated between these signaling pathways to plant development. The phase transition from embryonic to vegetative growth is studied. A GWAS screen is done to pick up novel genes involved during this transition and the effects of the TOR and SnRK1 pathway are investigated. Concluding, the transcriptional analysis reveals crosstalk and antagonism between TOR and SnRK1 signaling networks. Specifically, the induction of SnRK1 target genes is repressed via the TOR signaling pathway. In relation to development, sugar-induced dark morphogenesis for the developmental transition between embryonic and vegetative growth in Arabidopsis thaliana is completely TOR dependent. The SnRK1 pathway with bZIP11 is a key repressor of sugar induced dark-morphogenesis via connections with the ABA signaling network.