Sperm cells have an essential role in plant fertility, seed production and ultimately food security, but there remains limited knowledge of the molecular mechanisms involved in their development. This research aims to uncover novel aspects of the mechanisms underpinning key decisions in male gamete development and their evolution.
We have identified key regulators of plant sperm cell development, including the male germline-specific R2R3 MYB transcription factor DUO1, which is widely conserved and present in important food crop plants such as rice and tomato (Brownfield et al. 2009). This work has established a regulatory framework in plant germline development (Berger and Twell, 2011), and in recent work we have discovered a pair of novel zinc finger transcription factors (DAZ1 & DAZ2) that act as transcriptional repressors downstream of DUO1 in the DUO1-DAZ1 network (Borg et al., 2011, 2014).
Project Aims & Description.The project aims to explore both the functional role and evolution of germline-specific gene networks in plant sexual reproduction. The project will characterise novel mutants which impact upon DUO1-DAZ1 network function in flowering plants, and in a second strand, the evolutionary innovations associated with the transition from the differentiation of motile sperm in bryophytes, to the production of non-motile sperm in pollen of flowering plants. The research will increase understanding of the evolution of germline regulators in plants and is expected to deliver information and novel tools of potential value in plant biotechnology and breeding applications.
1. Novel genetic mechanisms involved in DUO1-DAZ1 network function will be examined by characterising novel suppressor mutants, which rescue defective germline development and male fertility. This will involve genetic and phenotypic analysis including crosses, cell fate marker studies and cell biological analysis of seed development. Selected mutant loci will be identified by whole
genome sequencing for further molecular analysis.
2. To explore DUO1-DAZ1 network conservation, existing knockout mutants and germline transcriptome data from the early land plants, Physcomitrella patens (moss) and Marchantia polymorpha (liverwort), will be characterised. Comparative transcriptomic analysis together with existing mutant germ cell data from flowering plants will be used to uncover shifts in germline gene regulatory networks. This will enable their impact on sperm cell differentiation and plant fertility to be explored.
The project presents an ideal opportunity for challenging research and novel discoveries in a well-supported environment. The successful candidate will receive an excellent grounding in plant molecular genetics and cell biology techniques, as well as in bioinformatics and the potential applications of fundamental research in plant biotechnology. Enthusiastic students with interests in plant development and gene regulation and who work well in a team environment are encouraged to apply.
Techniques that will be undertaken during the project:
Plant transformation and transient gene expression assays.
Fluorescence and confocal laser scanning microscopy.
Gene expression manipulation by overexpression & use of T-DNA and CRISPR/Cas9 knockouts.
Comparative transcriptomics (including microarray & RNA-seq data).
We are an equal opportunities employer and particularly welcome applications for Ph.D. places from women,
minority ethnic and other under-represented groups.
Borg, M., Brownfield, L., Khatab, H., Sidorova, A., Lingaya, M. and Twell, D. (2011) The R2R3 MYB transcription factor DUO1 activates a male germline-specific regulon essential for sperm cell differentiation in Arabidopsis. Plant Cell 23:1-16
Borg, M., Rutley, N., Kagale, S. Hamamura, Y., Gherghinoiu, M., Kumar, S., Sari, U., Esparza-Franco, MA., Sakamoto, W., Rozwadowski, K., Higashiyama, T. and Twell, D. (2014). An EAR-dependent regulatory module promotes male germ cell division and sperm fertility in Arabidopsis. Plant Cell 26:1-17
Brownfield, L., Hafidh, S., Borg, M., Sidorova, A., Mori, T. and Twell, D. (2009) A plant germ cell-specific integrator of cell cycle progression and sperm specification PLoS Genet. 5: e1000430
Kim, H.J., Oh, S-A., Brownfield, L., Ryu, H., Hwang, I., Twell, D*. and Nam, H-G*. (2008) Control of plant male germline proliferation by SCFFBL17 degradation of cell cycle inhibitors. Nature 455, 1134-1137
Berger, F. and Twell, D. (2011) Germline specification and function in plants. Annu Rev Plant Biol 62:461-484.