Phosphate-sensing mechanisms

Phosphate (Pi) is an essential nutrient for all organisms, and Pi is required for many key processes in plants, including carbohydrate metabolism, photosynthesis, respiration and signal transduction. Furthermore, phosphate is used in the biosynthesis of essential molecules such as adenylates, RNA, DNA and membrane lipids. Phosphate needs to be mobilised from the soil, taken up by roots, transported, distributed and re-distributed in the plant and, at the cellular level, phosphate is metabolised and re-mobilised from metabolic pools. and  Pi has a central role in plant growth and metabolism.

 

Despite abundance of phosphorus (P) in the rhizosphere the bioavailability is low. Plants have therefore evolved an array of strategies to obtain adequate Pi-supply under limiting conditions. These strategies rely on a close regulation of a large number of genes in response to Pi-starvation. To this end, plants recruit specific proteins, transcriptions factors, which will recognise and activate or inactivate important gene. However, the molecular devices to receive and communicate the external and internal Pi status remain to be elucidated in plants.

 

The aim of our research is to identify regulatory patterns in gene expression and in metabolism during P-starvation and to discover molecular interactions mediating regulation of gene expression in response to nutrient stress with focus on phosphate sensing. Our research is presently focused on analysis of a family of transcriptions factors, their role in regulation of nutrient acquisition and elucidation of the molecular interactions needed for their operation.

 

 

An important lead in this research area came with the discovery of a MYB-related transcription factors, PSR1 in  Chlamydomonas (Wykoff et al., 1999, PNAS 96: 15336-) and PHR1 in Arabidopsis (Rubio et al., 2001, Gene Dev 15: 2122-33) which are involved in P-starvation signalling. In Arabidopsis, we can identify a family of related TFs likely to mediate nutrient starvation responses. By a systematic approach we analyze this group of transcription factors to establish their mechanism of operation and their biological function.

 

 

The project takes advantage of recent developments for the model plant Arabidopsis, including full genome annotation, available T-DNA-tagged mutants, affordable full genome DNA-microarrays and recombinatorial vector construction for plant transformation and heterologous expression.

 

Conference contributions

Poster:
Lena Nilsson, Tom Hamborg Nielsen, Renate Müller (2007) "Increased expression of a MYB-related transcription factor, PHR1, leads to enhanced P-uptake in Arabidopsis thaliana" presented at: "Biochmical Society Focussed Meeting, Intercellular Signalling in Plants" Sept 4-5, 2006, Sheffield, UK and at Plant Biotech Denmark, Annual meeting 2007, Jan 23-24. Copenhagen , Denmark.

 

We are also involved in a newly started (Jan. 2007) collaborative project on the role of phosphate transporters in plants. Read more at the project homepage. 
  

The persons currently working at the project:

Tom Hamborg Nielsen, Associate Professor, E-mail:
Lena Nilsson, post doc. 
Helle Mogensen, Technician, E-mail:
Chloe, Meier, Technician trainee, E-mail: