Regulation of plasmodesmata signalling and transport by the CLAVATA1 and ARABIDOPSIS CRINKLY 4 receptor-like kinases

Meristems are the stem cell reservoirs that enable plants to grow and develop throughout their lifetime.

Meristem activities shape a plant’s architecture and phenotype, and enable it to acclimate and respond to its environment. However, little is known of the mechanisms through which meristem maintenance and functions are regulated.

The receptor-like kinase (RLK) CLAVATA1 (CLV1) promotes cell differentiation and forms a negative feedback loop with the mobile, stem cell fate-promoting transcription factor WUSCHEL (WUS) in the shoot meristem to balance the generation of new organs with stem cell maintenance.

Mutations in the CLV1 pathway are responsible for several advantageous crop traits achieved through selective breeding, such as larger tomato fruit, making meristems the focus of further attempts to improve crop productivity.

A similar stem cell control pathway acts in the root meristem, involving the RLKs ARABIDOPSIS CRINKLY 4 (ACR4) and CLV1, which form complexes that preferentially localise to plasmodesmata (PDs).

This led to the hypothesis that these complexes control the symplastic exchange of molecules, such as transcription factors that promote stem cell fate, through PDs.

Here I will use state-of-the-art proteomics, super-resolution nanoscopy and high-resolution in vivo fluorescence microscopy methods to characterise these PD-localised RLK complexes in Arabidopsis, and identify novel downstream signalling effectors.

Using CRISPR knock-out mutants and novel in vivo signalling and transport assays, I will analyse the roles of CLV1/ACR4-signalling in regulating PD signalling and transport, and in controlling meristem maintenance and development.

A greater understanding of CLV1/ACR4-signalling functions and the effect of changes in regulatory gene expression will enable the development of synthetic peptides or targeted plant breeding strategies to control plant phenology and architecture, ensuring crops can be adapted to grow in an ever-changing climate.