Zinc deficiency up-regulates expression of high-affinity phosphate transporter genes in both phosphate-sufficient and -deficient barley roots.

Phosphate (P) is taken up by plants through high-affinity P transporter proteins embedded in the plasma membrane of certain cell types in plant roots. Expression of the genes that encode these transporters responds to the P status of the plants, and their transcription is normally tightly controlled. However, this tight control of P uptake is lost under Zn deficiency, leading to very high accumulation of P in plants. We examined the effect of plant Zn status on the expression of the genes encoding the HVPT1 and HVPT2 high-affinity P transporters in barley (Hordeum vulgare L. cv Weeah) roots. The results show that the expression of these genes is intimately linked to the Zn status of the plants. Zn deficiency induced the expression of genes encoding these P transporters in plants grown in either P-sufficient or -deficient conditions. Moreover, the role of Zn in the regulation of these genes is specific in that it cannot be replaced by manganese (a divalent cation similar to Zn). It appears that Zn plays a specific role in the signal transduction pathway responsible for the regulation of genes encoding high-affinity P transporters in plant roots. The significance of Zn involvement in the regulation of genes involved in P uptake is discussed.

[1]  B. Persson,et al.  Phosphate permeases of Saccharomyces cerevisiae: structure, function and regulation. , 1999, Biochimica et biophysica acta.

[2]  F. W. Smith,et al.  Regulation of Expression of Genes Encoding Phosphate Transporters in Barley Roots , 1999 .

[3]  T. Mimura.  Regulation of Phosphate Transport and Homeostasis in Plant Cells , 1999 .

[4]  K. Raghothama,et al.  Transcriptional regulation of plant phosphate transporters. , 1999, Proceedings of the National Academy of Sciences of the United States of America.

[5]  H. Marschner,et al.  Mechanism of phosphorus‐induced zinc deficiency in cotton. II. Evidence for impaired shoot control of phosphorus uptake and translocation under zinc deficiency , 1986 .

[6]  Ross M. Welch,et al.  Growth and Nutrient Uptake by Barley (Hordeum vulgare L. cv Herta): Studies Using an N-(2-Hydroxyethyl)ethylenedinitrilotriacetic Acid-Buffered Nutrient Solution Technique (I. Zinc Ion Requirements) , 1993, Plant physiology.

[7]  Z. Rengel,et al.  Phosphate uptake in Arabidopsis thaliana: dependence of uptake on the expression of transporter genes and internal phosphate concentrations , 1999 .

[8]  F. W. Smith,et al.  Molecular mechanisms of phosphate and sulphate transport in plants. , 2000, Biochimica et biophysica acta.

[9]  J. Loneragan,et al.  Interactions Between Zinc and Other Nutrients Affecting the Growth of Plants , 1993 .

[10]  K. Raghothama,et al.  Tomato phosphate transporter genes are differentially regulated in plant tissues by phosphorus. , 1998, Plant physiology.

[11]  J. Loneragan,et al.  Effect of Zinc Deficiency on Growth, Phosphorus Concentration, and Phosphorus Toxicity of Wheat Plants , 1988 .

[12]  D. Parker,et al.  GEOCHEM‐PC—A Chemical Speciation Program for IBM and Compatible Personal Computers , 1995 .

[13]  Ross M. Welch,et al.  Growth and Nutrient Uptake by Barley (Hordeum vulgare L. cv Herta): Studies Using an N-(2-Hydroxyethyl)ethylenedinitrilotriacetic Acid-Buffered Nutrient Solution Technique (II. Role of Zinc in the Uptake and Root Leakage of Mineral Nutrients) , 1993, Plant physiology.

[14]  S. A. Barber,et al.  Soil Nutrient Bioavailability: A Mechanistic Approach , 1984 .

[15]  D. Clarkson,et al.  Growth and Phosphate Transport in Barley and Tomato Plants During the Development of, and Recovery from, Phosphate-stress , 1982 .

[16]  Jb Robinson,et al.  Plant Analysis: An Interpretation Manual , 1997 .

[17]  B. Zarcinas,et al.  Nitric acid digestion and multi‐element analysis of plant material by inductively coupled plasma spectrometry , 1987 .

[18]  K. Raghothama,et al.  Phosphate transporters from the higher plant Arabidopsis thaliana. , 1996, Proceedings of the National Academy of Sciences of the United States of America.

[19]  H. Marschner,et al.  Mechanism of phosphorus-induced zinc deficiency in cotton. I: Zinc deficiency-enhanced uptake rate of phosphorus , 1986 .

[20]  S. Mori,et al.  Differential expression of iron deficiency‐induced genes in barley genotypes with differing manganese efficiency , 1996 .

[21]  Ross M. Welch,et al.  Phosphorus Accumulation and Toxicity in Leaves in Relation to Zinc Supply1 , 1982 .

[22]  N. Ogawa,et al.  Regulation of phosphatase synthesis in Saccharomyces cerevisiae--a review. , 1996, Gene.

[23]  E. Delhaize,et al.  The cloning of two Arabidopsis genes belonging to a phosphate transporter family. , 1997, The Plant journal : for cell and molecular biology.

[24]  A. Gupta,et al.  Differential Susceptibility of Corn Cultivars to Zinc Deficiency1 , 1979 .

[25]  L. Willmitzer,et al.  Two cDNAs from potato are able to complement a phosphate uptake-deficient yeast mutant: identification of phosphate transporters from higher plants. , 1997, The Plant cell.