Research

 

We are interested in the epigenetic control of plant development. Because epigenetic changes are stable during the life of an organism, but can be reset each new generation, they can be used to provide cells with a ‘memory’ of transient developmental events.

We have identified several genes which provide plant cells with an epigenetic memory of their identity. Recent research suggests they do this by regulating histone methylation, leading to stable changes in expression of specific target genes:

 

 

The CURLY LEAF gene encodes a histone methyltransferase enzyme. Mutants are early flowering and have curled leaves. These defects arise because the gene AGAMOUS, normally expressed only in flowers, is activated precociously during vegetative development.

 

Double mutants for CURLY LEAF and SWINGER show a more extreme phenotype. Plants are only viable if grown in tissue culture and form callus with somatic embryos. Cytogenetic analysis indicates that these plants have gross defects in histone methylation patterns.

 

Current Research Aims:

To identify novel plant Polycomb genes and their antagonists, we conducted a large genetic screen for mutations modifying polycomb mutant phenotypes. We have isolated several of the genes involved and are characterising how they regulate gene activity. In collaboration with the group of Gwyneth Ingram, we are also analysis the role of the ZHOUPI (ZOU) gene in regulating epidermal development during embryogenesis in Arabidopsis. The ZOU gene encodes a transcription factor that promotes signalling from the endosperm to the young embryo and is required for normal epidermal development. We have identified several novel targets of ZOU and are currently testing their role in seed development.

 

 

Rogue Gene is Poacher turned Gamekeeper, Study Shows

A large fraction of the DNA of all plants and animals is made of genes known as transposons, so named because they can move from one area of DNA to another.  These genes are often harmful to the organism in which they occur, but survive because they can multiply faster than they can be removed.  However a new study in plants shows that transposons can also evolve to have a beneficial role in living things.

A team of plant scientists, including Justin Goodrich in the School of Biological Sciences at the University of Edinburgh, has been studying a gene known as ALP1, which is known to have a beneficial role in activating genes that control flower formation.  In the new study the researchers were surprised to find that ALP1 is related to other genes that help transposons to proliferate. They found that the ALP1 protein has acquired a new role, as a member of the Polycomb protein family, which controls the activity of many genes in plants and animals. 

Curiously, Polycomb proteins have a role in suppressing the activity of transposons in plants.  The researchers speculate that the association of ALP1 with Polycomb proteins might have first arisen as a way to hinder the plants ability to control tranpsosons.  Subsequently the ALP1 gene appears to have been tamed as a result of the evolutionary process and now plays a role more beneficial for plants (see figure 1).  Researchers say the work is an important example of how evolution can recycle transposon genes for new ends.  In addition, the ALP1 gene may provide a useful tool for manipulating the activity of Polycomb proteins, which have many important roles in plant and also animal development.

 

Fig. 1. Genetic interaction between ALP1 and Polycomb genes.  The Curly Leaf (CLF) gene encodes one component of the plant Polycomb machinery.  Plants with a mutation in clf have reduced leaf development.  However if plants have mutations in both ALP1 and CLF, normal growth is restored.  Genetic interaction is a result of the interaction between ALP1 and Polycomb proteins.

The work was a collaboration between the groups of Justin Goodrich (Institute of Molecular Plant Science, University of Edinburgh), Franziska Turck (Max Plank Institute for Plant Breeding Research in Germany), Jean Finnegan (CSIRO, Australia) and Juri Rappsilber (Wellcome Trust Institute for Cell Biology, University of Edinburgh.  The study is published in PLoS Genetics (see Publications).