Arabidopsis JAGGED links floral organ patterning to tissue growth by repressing Kip-related cell cycle inhibitors

• Published in: Proceedings of the National Academy of Sciences - PNAS 2014-02, Vol.111 (7), p.2830-2835
• Main Authors: Schiessl, Katharina, Muiño, Jose M., Sablowski, Robert
• Format: Article
• Language: English
• Subjects: Analysis of Variance; Arabidopsis; Arabidopsis - growth & development; Arabidopsis Proteins - metabolism; Base Sequence; Biological Sciences; Cell cycle; Cell Cycle - physiology; Cell Cycle Proteins - metabolism; Cell growth; Cell walls; Chromatin Immunoprecipitation; Cryoelectron Microscopy; Cyclin-Dependent Kinase Inhibitor Proteins - antagonists & inhibitors; Developmental biology; DNA Replication - genetics; DNA Replication - physiology; Epidermal cells; Flowers & plants; Flowers - growth & development; Flowers - ultrastructure; Gene Expression Profiling; Gene Expression Regulation, Plant - genetics; Genes; Genes, Regulator - genetics; Genes, Regulator - physiology; Meristems; Molecular Sequence Data; Morphogenesis - physiology; Morphology; Petals; Plant cells; Plants; Real-Time Polymerase Chain Reaction; Sequence Analysis, DNA; Tissues
• ISSN: 0027-8424; 1091-6490
• DOI: 10.1073/pnas.1320457111

Plant morphogenesis requires coordinated cytoplasmic growth, oriented cell wall extension, and cell cycle progression, but it is debated which of these processes are primary drivers for tissue growth and directly targeted by developmental genes. Here, we used ChIP high-throughput sequencing combined with transcriptome analysis to identify global target genes of the Arabidopsis transcription factor JAGGED (JAG), which promotes growth of the distal region of floral organs. Consistent with the roles of JAG during organ initiation and subsequent distal organ growth, we found that JAG directly repressed genes involved in meristem development, such as CLAVATA1 and HANABA TARANU , and genes involved in the development of the basal region of shoot organs, such as BLADE ON PETIOLE 2 and the GROWTH REGULATORY FACTOR pathway. At the same time, JAG regulated genes involved in tissue polarity, cell wall modification, and cell cycle progression. In particular, JAG directly repressed KIP RELATED PROTEIN 4 (KRP4) and KRP2, which control the transition to the DNA synthesis phase (S-phase) of the cell cycle. The krp2 and krp4 mutations suppressed jag defects in organ growth and in the morphology of petal epidermal cells, showing that the interaction between JAG and KRP genes is functionally relevant. Our work reveals that JAG is a direct mediator between genetic pathways involved in organ patterning and cellular functions required for tissue growth, and it shows that a regulatory gene shapes plant organs by releasing a constraint on S-phase entry.