The founder-cell transcriptome in the Arabidopsis apetala1 cauliflower inflorescence meristem

• Published in: BMC genomics Vol. 17; no. 1; p. 855
• Main Authors: Frerichs, Anneke, Thoma, Rahere, Abdallah, Ali Taleb, Frommolt, Peter, Werr, Wolfgang, Chandler, John William
• Format: Journal Article
• Language: English
• Published: England BioMed Central 03-11-2016
• Subjects: Brassica - genetics; Cluster Analysis; Computational Biology - methods; Epigenesis, Genetic; Gene Expression; Gene Expression Profiling; Gene Expression Regulation, Developmental; Gene Expression Regulation, Plant; Gene Ontology; Gene Regulatory Networks; Genes, Reporter; Genomics; Inflorescence - genetics; Meristem - genetics; Phenotype; Plant Cells - metabolism; RNA Processing, Post-Transcriptional; Transcriptome; Fluorescence-activated cell sorting; apetala1 cauliflower; RNA-seq; Bract; Transcriptome; Lateral organ founder cell; DORNRÖSCHEN-LIKE; Inflorescence meristem
• DOI: 10.1186/s12864-016-3189-x
• EISSN: 1471-2164

Although the pattern of lateral organ formation from apical meristems establishes species-specific plant architecture, the positional information that confers cell fate to cells as they transit to the meristem flanks where they differentiate, remains largely unknown. We have combined fluorescence-activated cell sorting and RNA-seq to characterise the cell-type-specific transcriptome at the earliest developmental time-point of lateral organ formation using DORNRÖSCHEN-LIKE::GFP to mark founder-cell populations at the periphery of the inflorescence meristem (IM) in apetala1 cauliflower double mutants, which overproliferate IMs.
Within the lateral organ founder-cell population at the inflorescence meristem, floral primordium identity genes are upregulated and stem-cell identity markers are downregulated. Additional differentially expressed transcripts are involved in polarity generation and boundary formation, and in epigenetic and post-translational changes. However, only subtle transcriptional reprogramming within the global auxin network was observed.
The transcriptional network of differentially expressed genes supports the hypothesis that lateral organ founder-cell specification involves the creation of polarity from the centre to the periphery of the IM and the establishment of a boundary from surrounding cells, consistent with bract initiation. However, contrary to the established paradigm that sites of auxin response maxima pre-pattern lateral organ initiation in the IM, auxin response might play a minor role in the earliest stages of lateral floral initiation.