Expression of the OsPI1 gene, cloned from rice roots using cDNA microarray, rapidly responds to phosphorus status

Abstract

Summary Plants have developed several methods of adapting to conditions of low phosphorus (P). However, details of the regulation of the gene expression system that responds to P status of plants is unknown. Here, a phosphorus limitation inducible novel gene was isolated and characterized to provide further information of plant adaptation to low P. Rice plants (Oryza sativa) were grown hydroponically with or without P. A novel gene was isolated by cDNA microarray analysis and designated as OsPI1 (Oryza sativaPhosphate‐limitation Inducible Gene 1). mRNA accumulation was examined by Northern blot and quantitative real time PCR. The OsPI1 gene was rapidly induced by phosphate starvation in both shoots and roots. When phosphate was supplied to phosphate‐deficient plants, the OsPI1 transcripts rapidly disappeared. OsPI1 cDNA consisted of 375 bp and contained several small open reading frames (ORFs). The OsPI1 gene shows the same characteristics as the TPSI1/Mt4 family (the phosphate starvation inducible novel gene family). It is suggested that OsPI1 acts as riboregulator, that is, it binds with other molecules under phosphate starvation and regulates their function.

Stress Response Versus Stress Tolerance: A Transcriptome Analysis of Two Rice Lines Contrasting in Tolerance to Phosphorus Deficiency

“…For example, we observed upregulation of P stress response genes related to Pi remobilization, including genes involved in lipid metabolism, phosphatases, and other genes belonging to the P scavenging system, as well as genes involved with P transporters, translocators, and antiporters; alteration of carbohydrates, amino acids, and protein metabolism; and alteration of secondary metabolism and photosynthesis. While this confirms other reports that these genes are associated with P stress response in P-deficient plants (Wasaki et al 2003;Misson et al 2005;Morcuende et al 2007), these responses were typically less pronounced in NIL6-4. Our transcriptome data therefore do not support the hypothesis that tolerance of NIL6-4 is the result of superior internal P use efficiency due to more efficient Pi remobilization.…”

“…P-deficiency-induced alterations in gene expression that would increase carbon supply for organic acid synthesis have been reported for rice (Wasaki et al 2003) and Arabidopsis (Morcuende et al 2007). We have detected the upregulation of genes, under P deficiency, coding for enzymes related to carbon flow through glycolysis to TCA (such as PFK, PFP, PEPCase, and pyruvate kinase).…”

“…Plant response to P deficiency has been analyzed at the transcriptome level in both Arabidopsis (Hammond et al 2003;Misson et al 2005;Morcuende et al 2007) and rice (Wasaki et al 2003(Wasaki et al , 2006Wang et al 2006). These studies were carried out in nutrient solutions or other artificial media and had detected a series of adaptive responses at the transcriptome levels that (1) circumvent metabolic steps requiring Pi by utilizing alternative glycolytic or respiratory pathways; (2) alter the lipid composition by enzymatic degradation of phospholipids and synthesis of galactolipid and sulfolipids; (3) remobilize Pi through enhanced expression of phosphatases and RNases; (4) enhance Pi uptake and retranslocation via an upregulation of highaffinity Pi transporters; (5) alter the carbon skeleton flow with potential benefits for root growth or organic acid synthesis and exudation; and (6) are involved in signal transduction and transcriptional regulation.…”

“…Microarray studies in Arabidopsis thaliana (Hammond et al 2003;Misson et al 2005;Morcuende et al 2007) and rice (Wasaki et al 2003;Wang et al 2006;Wasaki et al 2006) have confirmed the Pi responsiveness of many gene families involved in Pi acquisition and P remobilization and redistribution. Despite the valuable insights gained from these studies, it has so far been difficult to draw practically relevant conclusions because distinguishing stress response mechanisms/genes from those leading to elevated tolerance remains difficult.…”

Phosphate Utilization Efficiency Correlates with Expression of Low-Affinity Phosphate Transporters and Noncoding RNA, IPS1, in Barley

“…IPS genes are highly responsive to P deficiency, and their transcript levels are a good biomarker for P deficiency responses (Liu et al, 1997;Martín et al, 2000;Wasaki et al, 2003). IPS transcripts also interact with miR399s, regulating P translocation (Franco-Zorrilla et al, 2007).…”