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Molecular networks underpinning germination in land plants

Principal Supervisor: Juliet Coates - School of Biosciences

Co-supervisor: George Bassel

PhD project title: Molecular networks underpinning germination in land plants

University of Registration: Birmingham

Project outline:

All land plants produce desiccation-resistant structures at one point in their life cycle, which enable the transition between one generation and the next. The desiccation-resistant structure in seed plants is a multicellular, complex seed, while in early-evolving land plants (bryophytes, lycophytes and euphyllophytes) the functionally equivalent structure is the simple, single-celled spore. Spores and seeds are key for ensuring species survival, particularly under adverse climatic conditions. Around 70% of the world’s calories come from seeds. Many signals and responses controlling seed germination in model plants such as Arabidopsis are relatively well understood at the molecular level, although fundamental knowledge gaps remain (1). By contrast, the control of spore germination is almost completely undetermined. Recent work in Arabidopsis (2) suggests that a single phase of seed germination involves the co-ordinated regulation of evolutionarily ancient genes. Supporting this finding, the Coates lab has uncovered preliminary evidence that spores of the model early-evolving land plant Physcomitrella are regulated by many of the same environmental and hormonal signals that regulate seed germination, but that the molecular networks of interacting signals are “wired together” in a completely novel way (3,4). We propose that this situation is analogous to that previously discovered for the formation and evolution of rooting structures (5,6,7). Moreover, we also have evidence that, contrary to previous dogma, a gibberellin-like signalling pathway analogous to that in flowering plants exists in Physcomitrella (E. Vesty, B. King, H. Sorensen, J. Coates et al., unpublished). Uncovering a novel Physcomitrella germination network that responds to the same environmental signals as seeds opens up to a powerful future ‘synthetic biology’ approach to engineering new crop plants: replacing endogenous germination-regulatory genes in seed plants with parts of the core Physcomitrella germination network will produce plants with a completely novel germination response to known environmental inputs, thus changing the ecological niches and environmental extremes in which particular crop species can survive.

This project will use the moss Physcomitrella, which has a sequenced genome and well-established molecular genetics, to:

  1. Test a signals and mutants in combination for their effects on spore germination, thus developing a “matrix” of environment-hormone-signalling pathway interactions.
  2. Determine transcriptional changes occurring during spore germination using RT-PCR, qRT-PCR and RNAseq.
  3. Further investigate the role of diterpene signalling in Physcomitrella germination.
  4. Test the function of key Physcomitrella genes in the network identified in (1) - (3) using molecular genetics and novel imaging techniques to examine the mechanics of spore germination at high resolution.
  5. Begin to engineer the Physcomitrella germination network into Arabidopsis and test the effects on seed germination in response to controlled environmental signals.

References: 

  1. Nonogaki H, Bassel GW, Bewley JD (2010) Plant Science 179: 574-581
  2. Dekkers B et al., (2013) Plant Physiology 163: 205-15
  3. Moody LA et al., (2016) New Phytologist doi: 10.1111/nph.13938
  4. Vesty et al., (2016) New Phytologist doi: 10.1111/nph.14018
  5. Menand B et al., (2007) Science 316: 1477-80
  6. Jang G et al., (2011) Development 138: 2273-81
  7. Pires ND et al., (2013) PNAS 110: 9571-6

BBSRC Strategic Research Priority: Food Security

Techniques that will be undertaken during the project:

  • Mutant analysis, phenotypic assays
  • RT-PCR, qRT-PCR, RNA-seq
  • Molecular genetics (cloning, construct generation, etc)
  • Plant transformation
  • Imaging and computation

Contact: Dr Juliet Coates, University of Birmingham