DOI: 10.1101/514109Jan 8, 2019Paper

Neofunctionalisation of basic helix loop helix proteins occurred when plants colonised the land

BioRxiv : the Preprint Server for Biology
Clemence BonnotLiam Dolan


ROOT HAIR DEFECTIVE SIX-LIKE (RSL) genes control the development of structures (e.g. rhizoids, root hairs, gemmae, mucilage papillae) that develop from single cells at the surface of diverse groups of land plants. RSL proteins constitute a subclass (VIIIc) of the basic helix loop helix (bHLH) class VIII transcription factor family. We set out to determine if the function of RSL genes in the control of cell differentiation in land plants was inherited from streptophyte algal ancestor. The Charophyceae are a monophyletic class of streptophyte algae with tissue-like structures and rhizoids. We identified the single class VIII bHLH gene from the charophyceaen alga Chara braunii (CbbHLHVIII). Phylogenetic analysis suggests that this protein is sister to the RSL (bHLH subclass VIIIc) proteins and together they constitute a monophyletic group. Expression of CbbHLHVIII does not compensate for loss of the RSL function in either Marchantia polymorpha or Arabidopsis thaliana. Furthermore, CbbHLHVIII is expressed at sites of morphogenesis in C. braunii (e.g. the apices, nodes and gametangia) but not in rhizoids. This indicates that C. braunii class VIII protein is functionally different from land plant RSL proteins; they control rhizoid de...Continue Reading

Related Concepts

Cell Differentiation Process
Transcription Factor
Arabidopsis thaliana <plant>
Plant Roots

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