Dissecting the plant transcriptome and the regulatory responses to phosphate deprivation.
Inorganic phosphate (Pi) is an essential nutrient for plants, and the low bioavailability of Pi in soils is often a limitation to growth and development. Consequently, plants have evolved a range of regulatory mechanisms to adapt to phosphorus-starvation in order to optimise uptake and assimilation of Pi. Recently, significant progress has been made in elucidating these mechanisms. The coordinated expression of a large number of genes is important for many of these adaptations. Several global expression studies using microarray analysis have been conducted in Arabidopsis thaliana. These studies provide a valuable basis for the identification of new regulatory genes and promoter elements to further the understanding of Pi-dependent gene regulation. With focus on the Arabidopsis transcriptome, we extract common findings that point to new groups of putative regulators, including the NAC, MYB, ethylene response factor/APETALA2, zinc-finger, WRKY and CCAAT-binding families. With a number of new discoveries of regulatory elements, a complex regulatory network is emerging. Some regulatory elements, e.g. the transcription factor PHR1 and the microRNA (miRNA) miR399 and associated factors are well documented, yet not fully understood, whereas other suggested components need further characterisation. Here, we evaluate the contribution of the regulatory elements to the P-responses and present a model comprising factors directly or indirectly involved in transcriptional regulation and the role of miRNAs as regulators and long-distance signals. A striking feature is a series of feedback loops and parallel mechanisms that can modify and attenuate responses. We suggest that these mechanisms are instrumental in providing an accurate response and in keeping P-homeostasis.
Nilsson
Lena
L
Department of Plant Biology and Biotechnology, VKR Research Centre Pro-Active Plants, Faculty of Life Sciences, University of Copenhagen, Frederiksberg, Denmark.
Müller
Renate
R
Nielsen
Tom Hamborg
TH
D017360:Arabidopsis / Q000235:genetics / Q000378:metabolism*; D029681:Arabidopsis Proteins / Q000378:metabolism; D020869:Gene Expression Profiling; D018506:Gene Expression Regulation, Plant; D053263:Gene Regulatory Networks; D018745:Genome, Plant; D020411:Oligonucleotide Array Sequence Analysis; D010710:Phosphates / Q000378:metabolism*; D011401:Promoter Regions, Genetic; D014157:Transcription Factors / Q000378:metabolism
D029681:Arabidopsis Proteins; C514695:PHR1 protein, Arabidopsis; D010710:Phosphates; D014157:Transcription Factors