Regulated Expression of Arabidopsis Phosphate Transporters

Karthikeyan, Athikkattuvalasu S.; Varadarajan, Deepa K.; Mukatira, U. T.; D’Urzo, Matilde Paino; Damsz, Barbara; Raghothama, Kashchandra G.

doi:10.1104/pp.020007

Cited by 259 publications

(299 citation statements)

References 45 publications

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“…Nine PHT1 genes have been identified in Arabidopsis thaliana and 13 in rice (Oryza sativa) (Raghothama, 1999;Goff et al, 2002). Gene expression analysis showed that most PHT1 family members are temporally and spatially upregulated in response to Pi starvation (Karthikeyan et al, 2002;Mudge et al, 2002;Misson et al, 2004;Shin et al, 2004). Their expression patterns extend beyond the root, in line with their roles in both Pi uptake and translocation: crucial functions for maintaining the internal P homeostasis in plants.…”

Section: Introductionmentioning

confidence: 78%

“…In summary, there is a regulatory step at the ER whereby PHF1 enables the exit of PTs and phosphorylation by CK2 inhibits it by impeding PT-PHF1 interaction in addition to transcriptional control increasing PT levels in response to low Pi (Karthikeyan et al, 2002;Mudge et al, 2002). The activity of this kinase is affected by Pi supply, because reduced phosphorylation of CK2b3 results in its decreased stability and interaction capacity with CK2a3.…”

Section: A Ck2-integrated Model For Pt Er Exitmentioning

confidence: 99%

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The Rice CK2 Kinase Regulates Trafficking of Phosphate Transporters in Response to Phosphate Levels

et al. 2015

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Phosphate transporters (PTs) mediate phosphorus uptake and are regulated at the transcriptional and posttranslational levels. In one key mechanism of posttranslational regulation, phosphorylation of PTs affects their trafficking from the endoplasmic reticulum (ER) to the plasma membrane. However, the kinase(s) mediating PT phosphorylation and the mechanism leading to ER retention of phosphorylated PTs remain unclear. In this study, we identified a rice (Oryza sativa) kinase subunit, CK2b3, which interacts with PT2 and PT8 in a yeast two-hybrid screen. Also, the CK2a3/b3 holoenzyme phosphorylates PT8 under phosphate-sufficient conditions. This phosphorylation inhibited the interaction of PT8 with PHOSPHATE TRANSPORTER TRAFFIC FACILITATOR1, a key cofactor regulating the exit of PTs from the ER to the plasma membrane. Additionally, phosphorus starvation promoted CK2b3 degradation, relieving the negative regulation of PT phosphorus-insufficient conditions. In accordance, transgenic expression of a nonphosphorylatable version of OsPT8 resulted in elevated levels of that protein at the plasma membrane and enhanced phosphorus accumulation and plant growth under various phosphorus regimes. Taken together, these results indicate that CK2a3/b3 negatively regulates PTs and phosphorus status regulates CK2a3/b3.

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Section: Introductionmentioning

confidence: 78%

Section: A Ck2-integrated Model For Pt Er Exitmentioning

confidence: 99%

The Rice CK2 Kinase Regulates Trafficking of Phosphate Transporters in Response to Phosphate Levels

et al. 2015

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“…AtPT1 is another major high-affinity Pi transporter in Arabidopsis whose expression is also highly induced by Pi starvation (Muchhal et al, 1996;Karthikeyan et al, 2002). When hps1 mutation was introduced into the transgenic line carrying an AtPT1-GUS construct through a genetic cross, the expression of AtPT1-GUS was also highly induced under Pi starvation in the lateral roots around the hypocotyl-root junction and the root tips (Supplemental Fig.…”

Section: The Hps1 Mutation Enhances Pi Starvation-induced Gene Expresmentioning

confidence: 99%

“…S1). In this construct, a firefly luciferase (LUC) gene is fused to the promoter of the AtPT2 (AtPht1;4) gene, which encodes a high-affinity Pi transporter (Karthikeyan et al, 2002). Pi deficiency induced the expression of the reporter gene fused to the Pi starvation-responsive AtPT2 promoter.…”

Section: Identification Of the Hps1 Mutantmentioning

confidence: 99%

Genetic and Genomic Evidence That Sucrose Is a Global Regulator of Plant Responses to Phosphate Starvation in Arabidopsis

et al. 2011

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Plants respond to phosphate (Pi) starvation by exhibiting a suite of developmental, biochemical, and physiological changes to cope with this nutritional stress. To understand the molecular mechanism underlying these responses, we isolated an Arabidopsis (Arabidopsis thaliana) mutant, hypersensitive to phosphate starvation1 (hps1), which has enhanced sensitivity in almost all aspects of plant responses to Pi starvation. Molecular and genetic analyses indicated that the mutant phenotype is caused by overexpression of the SUCROSE TRANSPORTER2 (SUC2) gene. As a consequence, hps1 has a high level of sucrose (Suc) in both its shoot and root tissues. Overexpression of SUC2 or its closely related family members SUC1 and SUC5 in wild-type plants recapitulates the phenotype of hps1. In contrast, the disruption of SUC2 functions greatly inhibits plant responses to Pi starvation. Microarray analysis further indicated that 73% of the genes that are induced by Pi starvation in wild-type plants can be induced by elevated levels of Suc in hps1 mutants, even when they are grown under Pi-sufficient conditions. These genes include several important Pi signaling components and those that are directly involved in Pi transport, mobilization, and distribution between shoot and root. Interestingly, Suc and low-Pi signals appear to interact with each other both synergistically and antagonistically in regulating gene expression. Our genetic and genomic studies provide compelling evidence that Suc is a global regulator of plant responses to Pi starvation. This finding will help to further elucidate the signaling mechanism that controls plant responses to this particular nutritional stress.

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“…Pi transporters belonging to two major gene families (Pht1 and Pht2) have now been identified for a range of plant species (for review, see Rausch and Bucher, 2002) and have been most extensively studied in Arabidopsis (Arabidopsis thaliana; Muchhal et al, 1996;Mitsukawa et al, 1997;Smith et al, 1997Smith et al, , 2000Okumura et al, 1998;Karthikeyan et al, 2002;Mudge et al, 2002). The members of the gene family that are expressed in roots are typically up-regulated under P deficiency, but the molecular basis of the regulation has not been investigated.…”

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confidence: 99%

Promoter Analysis of the Barley Pht1;1 Phosphate Transporter Gene Identifies Regions Controlling Root Expression and Responsiveness to Phosphate Deprivation

et al. 2004

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Previous studies have shown that the promoter from the barley (Hordeum vulgare) phosphate transporter gene, HvPht1;1, activates high levels of expression in rice (Oryza sativa) roots and that the expression level was induced by up to 4-fold in response to phosphorus (P) deprivation. To identify promoter regions controlling gene regulation specificities, successive promoter truncations were made and attached to reporter genes. Promoters of between 856 and 1,400 nucleotides activated gene expression in a number of cell types but with maximal expression in trichoblast (root hair) cells. For shorter promoters the trichoblast specificity was lost, but in other tissues the distribution pattern was unchanged. The low P induction response was unaffected by promoter length. Domain exchange experiments subsequently identified that the region between 2856 and 2547 nucleotides (relative to the translational start) is required for epidermal cell expression. A second region located between 0 and 2195 nucleotides controls root-tip expression. The HvPht1;1 promoter contains one PHO-like motif and three motifs similar to the dicot P1BS element. Analysis of promoters from which the PHO-like element was eliminated (by truncation) showed no change in the gene induction response to P deficiency. In contrast, mutation of the P1BS elements eliminated any induction of gene expression in response to low P. An internal HvPht1;1 promoter fragment, incorporating a single P1BS element, had an increased response to P deprivation in comparison with the unmodified promoter (containing three elements). Together these findings further our understanding of the regulation of the HvPht1;1 gene and provide direct evidence for a functional role of the P1BS element in the expression of P-regulated genes.

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Regulated Expression of Arabidopsis Phosphate Transporters

Cited by 259 publications

References 45 publications

The Rice CK2 Kinase Regulates Trafficking of Phosphate Transporters in Response to Phosphate Levels

The Rice CK2 Kinase Regulates Trafficking of Phosphate Transporters in Response to Phosphate Levels

Genetic and Genomic Evidence That Sucrose Is a Global Regulator of Plant Responses to Phosphate Starvation in Arabidopsis

Promoter Analysis of the Barley Pht1;1 Phosphate Transporter Gene Identifies Regions Controlling Root Expression and Responsiveness to Phosphate Deprivation

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