Spatio‐temporal expression dynamics differ between homologues of flowering time genes in the allopolyploid Brassica napus

• Published in: The Plant journal : for cell and molecular biology Vol. 96; no. 1; pp. 103 - 118
• Main Authors: Jones, D. Marc, Wells, Rachel, Pullen, Nick, Trick, Martin, Irwin, Judith A., Morris, Richard J.
• Format: Journal Article
• Language: English
• Published: England Blackwell Publishing Ltd 01.10.2018; John Wiley and Sons Inc
• Subjects: Adaptive radiation; Angiosperms; Brassica; Brassica napus; Brassica napus - genetics; Brassica napus - growth & development; Case studies; Complexity; Divergence; Flowering; flowering time; Flowers - genetics; Gene duplication; Gene Duplication - genetics; Gene expression; Gene Expression Regulation, Developmental; Gene Expression Regulation, Plant; Genes; Genes, Plant - genetics; Genes, Plant - physiology; Genomes; Homology; Leaves; Original; Plant tissues; polyploid; Polyploidy; Radiation; Rape plants; Rapeseed; regulation; Regulatory sequences; Reproduction (copying); Speciation; time series; Brassica napus; polyploid; time series; regulation; flowering time; gene duplication
• ISSN: 0960-7412; 1365-313X
• DOI: 10.1111/tpj.14020

Summary Polyploidy is a recurrent feature of eukaryotic evolution and has been linked to increases in complexity, adaptive radiation and speciation. Within angiosperms such events have occurred repeatedly in many plant lineages. Here we investigate the retention and spatio‐temporal expression dynamics of duplicated genes predicted to regulate the floral transition in Brassica napus (oilseed rape, OSR). We show that flowering time genes are preferentially retained relative to other genes in the OSR genome. Using a transcriptome time series in two tissues (leaf and shoot apex) across development we show that 67% of these retained flowering time genes are expressed. Furthermore, between 64% (leaf) and 74% (shoot apex) of the retained gene homologues show diverged expression patterns relative to each other across development, suggesting neo‐ or subfunctionalization. A case study of homologues of the shoot meristem identity gene TFL1 reveals differences in cis‐regulatory elements that could explain this divergence. Such differences in the expression dynamics of duplicated genes highlight the challenges involved in translating gene regulatory networks from diploid model systems to more complex polyploid crop species. Significance Statement Many economically important crops exhibit extensive gene duplication due to recent or ancestral polyploidisation. This study demonstrates that flowering time genes have been preferentially retained in Brassica napus and that significant differences in the spatio‐temporal expression dynamics occur between gene homologues.