Plant and crop fertility: the evolution and impact of gene control networks

Plant fertility is vitally dependent upon sexual reproduction and the differentiation of male (sperm) and female (egg) gametes. Despite the importance of this process for future food security we have limited knowledge of the mechanisms involved in gamete development. This research aims to uncover fundamental mechanisms that underlie key decisions in gamete development and the role of gene networks in plant and crop fertility.

We have identified a key regulatory step in plant sperm cell development that involves the Arabidopsis thaliana transcription factor DUO1. This protein is widely conserved in important food crops such as maize, wheat, rice and tomato and forms a regulatory module with its target protein DAZ1 (a zinc finger transcription factor) (Borg et al., 2014). An exciting recent discovery is that this module is ancient and is even needed for sperm development in early land plants, such as mosses and liverworts (Higo et al., 2018).

Project Aims & Description
This project will explore the conservation and mechanisms by which the DUO1-DAZ1 module coordinates cell proliferation with sperm differentiation. Studies of gene function will involve those in crop species including tomato, as well as in early land plant models. Genetic and molecular analyses will be combined with comparative transcriptome studies to uncover co-expression and co-function gene networks. This will help to discover novel plant fertility genes of potential value. Overall, the project seeks to establish how gene function and evolution has shaped the fertility of some of our important food crops, starting from their earliest origins.

The impact of the research is also expected in the sphere of novel plant breeding applications including hybrid seed production and the control of gene flow.

Possible timeline
Year 1. Construct novel germline mutants using CRISPR-Cas9 technology and identify germline targets of the DUO1-DAZ1 regulon based on bioinformatic analysis of transcriptome data.
Year 2. Use genetic and molecular methods to analyse germline mutants and establish in vitro/in vivo DNA binding assays for DAZ1.
Year 3. Devise a network model for the contribution of DAZ1-targets to male germline development and analyse gene function by gene-editing and manipulation of protein function.

Techniques that will be undertaken during the project
Manipulation of gene expression and protein function by transgenic analysis and CRISPR-Cas9 gene-editing; Fluorescence and confocal laser scanning microscopy; Comparative transcriptome analysis (microarray & RNA-seq data); co-expression and co-function network analysis;Transient gene expression assays and quantitative analysis (qRT-PCR)